KICP in the News



 
Physics Today' cover page: The Dark Energy Survey
Physics Today, April 10, 2014
Physics Today, Volume 67, Issue 4, April 2014 cover: The Dark Energy Survey
Physics Today, Volume 67, Issue 4, April 2014
cover: The Dark Energy Survey
Physics Today

The Dark Energy Survey will conduct a five-year census of galaxies and stars over a full eighth of the night sky in an effort to understand what is driving the accelerating expansion of the cosmos. The survey will be carried out by the 570-megapixel Dark Energy Camera, photographed here in its black housing on the Victor M. Blanco Telescope in Chile. Josh Friemanís article on page 28 describes the science underlying the survey and some of the cameraís advanced technology.

Read more >>

Related Links:
KICP Members: Joshua A. Frieman
Scientific projects: Dark Energy Survey (DES)
 
Searching High & Low for Dark Matter
The Kavli Foundation, April 7, 2014
Image of excess gamma rays seen around the center of the Milky Way galaxy, detected by the Fermi Gamma-Ray Space Telescope.   <i>Credit: The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Compelling Case for Annihilating Dark Matter, Daylan et al., arXiv:1402.6703v1 [astro-ph.HE] 26 Feb 2014.<i>
Image of excess gamma rays seen around the center of the Milky Way galaxy, detected by the Fermi Gamma-Ray Space Telescope.

Credit: The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Compelling Case for Annihilating Dark Matter, Daylan et al., arXiv:1402.6703v1 [astro-ph.HE] 26 Feb 2014.
by Bruce Lieberman, The Kavli Foundation

An annual conference at the University of California, Los Angeles had researchers discussing the latest progress and challenges in the hunt for dark matter.

THERE'S MORE TO THE COSMOS THAN MEETS THE EYE. In late February, dark matter hunters from around the world gathered at the University of California, Los Angeles for "Dark Matter 2014." The annual conference is one of the largest of its kind aimed at discussing the latest progress in the quest to identify dark matter, the unknown stuff that makes up more than a quarter of the universe yet remains a mystery. Nearly 160 people attended, including renowned physicists from institutions across the United States and Europe, as well as from Japan, China and Canada.

So where does the hunt stand? Between sessions, three leading physicists at the conference spent an hour discussing its biggest highlights and prospects for future progress. Joining the special conversation:
* Blas Cabrera - Professor of Physics at Stanford University, and Member of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford. Spokesperson for the SuperCDMS dark matter experiment.
* Dan Hooper - Scientist in the Theoretical Astrophysics Group at the Fermi National Accelerator Laboratory, Associate Professor in the Department of Astronomy and Astrophysics at the University of Chicago, and Senior Member of the Kavli Institute for Cosmological Physics (KICP) at UChicago.
* Tim Tait - Professor of Physics and Astronomy at the University of California Irvine, and Member of UC Irvine's Theoretical Particle Physics Group.

The following is an edited transcript of the discussion.
THE KAVLI FOUNDATION: Almost everyone at the conference seems to think we're finally on the path toward figuring out what dark matter is. After 80 years of being in the "dark," what are we hearing at this meeting to explain the optimism?

BLAS CABRERA: This conference has highlighted the progression of larger and larger experiments with remarkable advances in sensitivity. What we're looking for is evidence of a dark matter particle, and the leading idea for what it might be is something called a weakly interacting massive particle, or WIMP. We believe the WIMP interacts with ordinary matter only very rarely, but we have hints from a few experiments that might be evidence for WIMPs.

Separately at this conference, we heard about improved calibrations of last fall's results from LUX, the Large Underground Xenon detector that now leads the world in sensitivity for WIMPs above the mass of six protons - a proton being the nucleus of a single hydrogen atom. Under a standard interpretation of the data, the LUX team has ruled out a range of low-end masses for the dark matter particle, another major advance because it does not see potential detections reported by other experiments and further narrows the possibilities for how massive the WIMP might be.

Finally, Dan [Hooper] also gave a remarkable presentation here about another effort: to indirectly detect dark matter by studying radiation coming from the center of the Milky Way galaxy. He reported the possibility of a strong dark matter signal, and I would say that was also one of the highlights of the conference because it provides us with some of the strongest evidence so far of a dark matter detection in space. Dan can explain.

DAN HOOPER: Four and a half years ago, I wrote my first paper on searching for evidence of dark matter at the center of the Milky Way galaxy. And now we think we have the most compelling results to date. What we're looking at is actually gamma rays - the most energetic form of light - radiating from the center of the galaxy. I think that this is very likely a signal of annihilating dark matter particles. As Blas explained, we believe dark matter is made of particles, and these particles, by themselves, are expected to be stable - meaning that they don't readily decay into other particles or forms of radiation. But at the dense core of the Milky Way galaxy, we think they collide and annihilate one another, in the process releasing huge amounts of energy in the form of gamma rays.

TIM TAIT: We expect that the density of dark matter particles, and therefore the intensity of the gamma-ray radiation released when they collide, should both fall as you move away from the galactic center. So, you sort of know what the profile of the signal should be, moving from the center of the galaxy outward.

TKF: So Dan, in this case the gamma rays that we observe radiating from the center of the Milky Way match our predictions for the mass of dark matter particles?

HOOPER: That's right. We predicted what the energy level of the gamma rays should be, based on established theories for how massive the WIMP should be, and what we've seen matches the simplest theoretical model for the WIMP. Our paper is based on more data, and we found more sophisticated ways of analyzing that data. We threw every test we could think of at it. We found that not only is the signal there and very statistically significant, its characteristics really look like what we would expect dark matter to produce - in the way that the gamma-ray radiation maps on the sky, in its general brightness, and in other features.


"A discovery of dark matter ...[means] we would have identified the dominant form of matter in the universe that seeded structure and led to galaxies, solar systems and planets, and ultimately to our Earth with intelligent life." - Blas Cabrera


TKF: Tell me a bit more about this prediction.

HOOPER: We think that all the particles that make up dark matter were all produced in the Big Bang nearly 14 billion years ago, and eventually as the universe cooled a small fraction survived to make up the dark matter we have today. The amount that has survived depends on how much the dark matter particles have interacted with one other over cosmic time. The more they collided and became annihilated, the less dark matter survives today. So, I can basically calculate the rate at which dark matter particles have collided over cosmic history - based on how much dark matter we estimate exists in the universe today. And once I have the rate of dark matter annihilation today, I can estimate how bright the gamma-ray signal from the galactic center should be - if it's made of WIMPS of a certain mass. And lo and behold, the observed gamma-ray signal is as bright as we predict it should be.

TKF: What else caught everyone's attention at the conference?

TAIT: A really striking result was from Super Cryogenic Dark Matter Search, or SuperCDMS, the direct detection experiment that Blas works on. They didn't find any evidence for dark matter, and that contradicts several other direct detection experiments that have claimed a detection in the same mass range.

CABRERA: What we're looking for is an exceedingly rare collision between an incoming WIMP and the nucleus of a single atom in our detector, which in SuperCDMS is made from germanium crystal. The collision causes the nucleus of a germanium atom to recoil, and that recoil generates a small amount of energy that we can measure.

Direct detection experiments are situated underground to minimize background noise from a variety of known sources of radiation, from space and on Earth. The new detectors that we built in SuperCDMS have allowed us to reject the dominant background noise that in the past clouded our ability to detect a dark matter signal. This noise was from electrons hitting the surface of the germanium crystal in the detector. The new design allows us to clearly identify and throw out these surface events. So, rather than saying, "Okay, maybe this background could be partly a signal," we can say with confidence now, "There is no background" and you have a very clean result. What this means is we have much more confidence in our data if we do make a potential detection. And if we don't, we're more confident that we're coming up empty. Eliminating background noise vastly reduces uncertainties in our analysis - whether we find something or not.

TKF: What caught everyone's attention on the theoretical side?

CABRERA: What struck me at this meeting is that nuclear physicists have recently written papers describing a generalized framework for all possible interactions between a dark matter particle and the nucleus of a single atom of the material that researchers use in their detectors; in the case of SuperCDMS, as I've explained, it's germanium and silicon crystals. These nuclear physicists have pointed out that roughly half of all possible interactions are not even being considered now. We are trying to digest what that means, but it suggests there are many more possibilities and a lot we still don't know.

TKF: Tim, with accelerators like the Large Hadron Collider in Europe, researchers are looking for evidence of supersymmetry, which could reveal the nature of dark matter. Tell me about this idea. Also, was anything new discussed at the meeting?

TIM TAIT: Supersymmetry proposes there are mirror particles that shadow all the known fundamental particles, and in this shadow world may lurk the dark matter particle. So, by smashing together protons in the LHC, we've tried to reveal these theoretical supersymmetric particles. So far, though, the LHC hasn't found any evidence for supersymmetry. It may be that our vision of supersymmetry isn't the only vision for physics beyond the Standard Model. Or maybe our vision for supersymmetry isn't a complete one.

TKF: The LHC is going to collide protons at much higher energy levels next year, so could that reveal something we just can't see right now?

TAIT: We hope so. We have very good reason to think that the lightest of the mirror particles in this shadow family is probably stable, so higher energy collisions could very well reveal them. If dark matter was formed early in the universe as a supersymmetric particle and it's still around - which we think it is - it could show up in the next round of LHC experiments.

TKF: When you think about the different approaches to identifying dark matter, has anything discussed at this meeting convinced you that one of them will be first?

TAIT: When you look at all the different ways of looking for dark matter, what you find is that they all have incredible strengths and they all have blind spots. And so you can't really say one is doing better than the other. You can say, though, they are answering different questions and doing very important things. Because even if you end up discovering dark matter in one place - let's say in the direct detection search - the fact that you do not see it at the LHC, for example, is already telling you something amazing about the theory. A negative result is actually just as important as a positive result.


"When you look at all the different ways of looking for dark matter, what you find is that they all have incredible strengths and they all have blind spots." - Tim Tait



HOOPER: The same goes with the direct detection experiments. I'm remarkably surprised that they haven't seen anything. We have this idea of where these supersymmetric particles and WIMP particles should show up in these experiments - at the LHC and in direct detection experiments - and yet lo and behold we got there and they are not there. But that doesn't mean they're not right around the corner, or maybe several corners away.

CABRERA: Given the remarkable progress over the past few years with many direct detection experiments, we would not have been surprised to have something rear its head that looks like a true WIMP.

HOOPER: Similarly, I think if you had done a survey of particle physicists five years ago, I don't think many of them would have said that in 2014 we've only discovered the Higgs - the fundamental particle that imparts mass to fundamental particles - and not anything else.

CABRERA: Now that the Higgs has been pretty convincingly seen, the next big questions for the accelerator community are: "What is dark matter? What is it telling us that we do not see dark matter at the LHC? What does that leave open?" These questions are being asked broadly, which wasn't the case in past years.

TKF: Was finding the Higgs, in a sense, an easier quest than identifying dark matter?

HOOPER: We knew what the Higgs should look like, and we knew what we would have to do to observe it. Although we didn't know exactly how heavy it would be.

CABRERA: We knew it had to be there.

HOOPER: If it weren't there it would have been weird. Now, with dark matter, there are hundreds and hundreds of different WIMP candidates that people have written down, and they all behave differently. So the Higgs is a singular idea, more or less, while the WIMP is a whole class of ideas.

TKF: What would a confirmed detection of dark matter really mean for what we know about the universe? And where would we go from there?

CABRERA: A discovery of dark matter with direct detection experiments would not be the end of the journey, but rather the beginning of a very exciting set of follow-up experiments. We would want to determine the mass and other properties of the particle with more precision, and we'd also want to better understand how dark matter is distributed in and around our galaxy. Follow-up experiments with detectors would use different materials, and we'd also try to map which direction the WIMPs are coming from through our detectors, which would help us better understand the nature of dark matter that surrounds the Earth.

Overall, a discovery would be huge for astrophysics and cosmology, and for elementary particle physics. For astrophysics we would have identified the dominant form of matter in the universe that seeded structure and led to galaxies, solar systems and planets, and ultimately to our Earth with intelligent life. On the particle physics side, this new particle would require physics beyond the Standard Model such as supersymmetry, and would allow us to probe this new sector with particle accelerators like the LHC.


"The history of science is full of discoveries opening up whole new avenues for exploration that were not foreseen." - Dan Hooper


TAIT: I think there's a lot of different ways you could look at it. From a particle physicist's point of view, we would now have a new particle that we'd have to put into our fundamental table of particles. We know that we see lots of structure in this table, but we don't really understand where the structure comes from.

From a practical point of view, and this is very speculative, dark matter is a frozen form of energy, right? Its mass is energy, and it's all around us. Personally, if I understood how dark matter interacts with ordinary matter, I would try to figure out how to build a reactor. And I'm sure that such a thing is not at all practical today, but someday we might be able to do it. Right now, dark matter just goes right through us, and we don't know how to stop it and communicate with it.

HOOPER: That was awesome, Tim. You blow my mind. I'm picturing a 25th century culture in which we harness dark matter to make an entirely new form of energy.

TAIT: By the way, Dan, I'm toying with the idea of writing a paper so we should keep talking.

HOOPER: I would love to hear more about it. That sounds great. So, to kind of echo some of what Tim said, the dark matter particle, once we identify it, has to fit into a bigger theory that connects it to the Standard Model. We don't really have any idea what that might look like. We have a lot of guesses, but we really don't know so there's a lot of work to do. Maybe this will help us build a grand unified theory - a single mathematical explanation for the universe - and help us, for example, understand things like gravity, which frankly we don't understand at all in a particle physics context. Maybe it will just open our eyes to entirely new possibilities that we just never considered until now. The history of science is full of discoveries opening up whole new avenues for exploration that were not foreseen. And I have every reason to think that that's not unlikely in this case.

- Writer: Bruce Lieberman, 2014

Read more >>

Related Links:
KICP Members: Daniel Hooper
 
Fermi Telescope data tantalize with new clues to dark matter
The University of Chicago News Office, April 3, 2014
This image shows the Milky Way in visible light and superimposes a gamma-ray map of the galactic center from NASA's Fermi Large Area Telescope. Raw data transitions to a view with all known sources removed, revealing a gamma-ray excess hinting at the presence of dark matter.  <i>Courtesy of NASA Goddard/A. Mellinger (Central Michigan Univ.) and T. Linden (Univ. of Chicago)</i>
This image shows the Milky Way in visible light and superimposes a gamma-ray map of the galactic center from NASA's Fermi Large Area Telescope. Raw data transitions to a view with all known sources removed, revealing a gamma-ray excess hinting at the presence of dark matter.

Courtesy of NASA Goddard/A. Mellinger (Central Michigan Univ.) and T. Linden (Univ. of Chicago)
by Francis Reddy, The University of Chicago News Office

A new study of gamma-ray light from the center of the galaxy makes the strongest case to date that some of this emission may arise from dark matter, an unknown substance making up most of the material universe.

Using publicly available data from NASA's Fermi Gamma-ray Space Telescope, independent scientists at the Fermi National Accelerator Laboratory, the Harvard-Smithsonian Center for Astrophysics (CfA), the Massachusetts Institute of Technology and the University of Chicago have developed new maps showing that the galactic center produces more high-energy gamma rays than can be explained by known sources and that this excess emission is consistent with some forms of dark matter.

"The new maps allow us to analyze the excess and test whether more conventional explanations, such as the presence of undiscovered pulsars or cosmic-ray collisions on gas clouds, can account for it," said Dan Hooper, University of Chicago associate professor in astronomy and astrophysics. A lead author of the study, Hooper also is an astrophysicist at Fermilab. "The signal we find cannot be explained by currently proposed alternatives and is in close agreement with the predictions of very simple dark matter models," he said.

The galactic center teems with gamma-ray sources, from interacting binary systems and isolated pulsars to supernova remnants and particles colliding with interstellar gas. It's also where astronomers expect to find the galaxy's highest density of dark matter, which only affects normal matter and radiation through its gravity. Large amounts of dark matter attract normal matter, forming a foundation upon which visible structures, like galaxies, are built.

No one knows the true nature of dark matter, but WIMPs, or Weakly Interacting Massive Particles, represent a leading class of candidates. Theorists have envisioned a wide range of WIMP types, some of which may either mutually annihilate or produce an intermediate, quickly decaying particle when they collide. Both of these pathways end with the production of gamma rays - the most energetic form of light - at energies within the detection range of Fermi's Large Area Telescope (LAT).

When astronomers carefully subtract all known gamma-ray sources from LAT observations of the galactic center, a patch of leftover emission remains. This excess appears most prominent at energies between 1 and 3 billion electron volts (GeV) - roughly a billion times greater than that of visible light - and extends outward at least 5,000 light-years from the galactic center.

Hooper and his colleagues conclude that annihilations of dark matter particles with a mass between 31 and 40 GeV provide a remarkable fit for the excess based on its gamma-ray spectrum, its symmetry around the galactic center and its overall brightness. Writing in a paper submitted to the journal Physical Review D, the researchers say that these features are difficult to reconcile with other explanations proposed so far, although they note that plausible alternatives not requiring dark matter may yet materialize.

"Dark matter in this mass range can be probed by direct detection and by the Large Hadron Collider (LHC), so if this is dark matter, we're already learning about its interactions from the lack of detection so far," said co-author Tracy Slatyer, theoretical physicist at MIT. "This is a very exciting signal, and while the case is not yet closed, in the future we might well look back and say this was where we saw dark matter annihilation for the first time."

The researchers caution that it will take multiple sightings - in other astronomical objects, the LHC or in some of the direct-detection experiments now being conducted around the world - to validate their dark matter interpretation.

"Our case is very much a process-of-elimination argument. We made a list, scratched off things that didn't work, and ended up with dark matter," said co-author Douglas Finkbeiner, professor of astronomy and physics at the CfA.

"This study is an example of innovative techniques applied to Fermi data by the science community," said Peter Michelson, professor of physics at Stanford University and the LAT principal investigator. "The Fermi LAT Collaboration continues to examine the extraordinarily complex central region of the galaxy, but until this study is complete we can neither confirm nor refute this interesting analysis."

While the great amount of dark matter expected at the galactic center should produce a strong signal, competition from many other gamma-ray sources complicates any case for detection. But turning the problem on its head provides another way to attack it. Instead of looking at the largest nearby collection of dark matter, look where the signal has fewer challenges.

Dwarf galaxies orbiting the Milky Way lack other types of gamma-ray emitters and contain large amounts of dark matter for their size - in fact, they're the most dark-matter-dominated sources known. But there's a tradeoff. Because they lie much farther away and contain much less total dark matter than the center of the Milky Way, dwarf galaxies produce a much weaker signal and require many years of observations to establish secure detection.

For the past four years, the LAT team has been searching dwarf galaxies for hints of dark matter. The published results of these studies has set stringent limits on the mass ranges and interaction rates for many proposed WIMPs, even eliminating some models. In the study's most recent results, published in Physical Review D on Feb. 11, the Fermi team took note of a small but provocative gamma-ray excess.

"There's about a one-in-12 chance that what we're seeing in the dwarf galaxies is not even a signal at all, just a fluctuation in the gamma-ray background," explained Elliott Bloom, a member of the LAT Collaboration at the Kavli Institute for Particle Astrophysics and Cosmology, jointly located at the SLAC National Accelerator Laboratory and Stanford University. If it's real, the signal should grow stronger as Fermi acquires additional years of observations and as wide-field astronomical surveys discover new dwarfs. "If we ultimately see a significant signal," he said, "it could be a very strong confirmation of the dark matter signal claimed in the galactic center."

Read more >>

Related Links:
KICP Members: Daniel Hooper; Tim Linden
 
Tremors from cosmic discovery reverberate through Kavli Institute
The University of Chicago News Office, March 21, 2014
Tremors from cosmic discovery reverberate through Kavli Institute
by Steve Koppes, The University of Chicago News Office

Scientists at the University of Chicago's Kavli Institute for Cosmological Physics are celebrating Monday's headline-making announcement that astronomers have acquired the first direct evidence of gravitational waves rippling through our infant universe during an explosive period of growth called inflation.

Researchers from the BICEP2 collaboration Monday announced the first direct evidence for this cosmic inflation. Their data also represent the first images of gravitational waves, or ripples in space-time. These waves have been described as the "first tremors of the Big Bang." On Wednesday afternoon, nearly 200 UChicago scientists assembled in Kersten Science Teaching Center for a special symposium presented by three BICEP2 collaborators.

"Detecting this signal is one of the most important goals in cosmology today. A lot of work by a lot of people has led up to this point," said John Kovac, PhD'04, of the Harvard-Smithsonian Center for Astrophysics and leader of the BICEP2 collaboration. The collaborations' co-leaders are Jamie Bock of the California Institute of Technology, Chao-Lin Kuo of Stanford University, and Clem Pryke of the University of Minnesota.

BICEP2's many collaborators include three members of the Kavli Institute: Abigail Vieregg, assistant professor in physics; Christopher Sheely, PhD'13, Kavli Institute fellow; and Erik Leitch, senior research associate.

"What an amazing discovery. The BICEP2 results are truly fantastic," said John Carlstrom, the S. Chandrasekhar Distinguished Service Professor in Astronomy & Astrophysics, who leads a competing project, the South Pole Telescope. "It is a fantastic day for cosmology and indeed for all of physics."

Carlstrom served as Kovac's graduate-school mentor. In 2002, Kovac was lead author of a Nature paper announcing the detection of a minute polarization of the cosmic microwave background using a radio telescope called the Degree Angular Scale Interferometer. The discovery verified the framework that supported modern cosmological theory, including cosmic inflation, which improbably proposed that the universe underwent a gigantic growth spurt in a fraction of a second after the Big Bang.

Tiny fluctuations, big clues
The dramatic new results came from observations by the BICEP2 telescope of the cosmic microwave background - afterglow from the Big Bang. Tiny fluctuations in this afterglow provide clues to conditions in the early universe. For example, small differences in temperature across the sky show where parts of the universe were denser, eventually condensing into galaxies and galactic clusters.

Since the cosmic microwave background is a form of light, it exhibits all the properties of light, including polarization. On Earth, sunlight is scattered by the atmosphere and becomes polarized, which is why polarized sunglasses help reduce glare. In space, the cosmic microwave background was scattered by atoms and electrons and became polarized, too.

Gravitational waves leave behind characteristic twisting patterns on the cosmic microwave background known as B-mode polarization. Researchers took an important first step toward measuring inflationary B modes last year when they detected B modes from gravitational lensing for the first time. Gravitational lensing is a phenomenon that occurs when the trajectory of light is bent by massive objects in space, much like a lens focuses light.

The detection of gravitational lensing B modes was published last September in Physical Review Letters by a multi-institutional collaboration of researchers led by Carlstrom. They used data from SPTpol, a polarization-sensitive camera installed on the South Pole Telescope in January 2012. Physics World magazine named this finding as named one of the top 10 physics breakthroughs of 2013.

Journalists and members of the public alike have displayed enthusiastic interest in Monday's inflationary B modes announcement. The story made the front page of Tuesday's New York Times, which quoted Carlstrom in a story headlined "Space Ripples Reveal Big Bang's Smoking Gun."

The Washington Post's coverage, meanwhile, included quote from Kavli Institute Director Michael Turner, the Bruce and Diana Rauner Distinguished Service Professor in Astronomy & Astrophysics. "Inflation - the idea of a very big burst of inflation very early on - is the most important idea in cosmology since the big bang itself," Turner hold the Post. "If correct, this burst is the dynamite behind our big bang."

Other coverage included a live interview with BICEP2 collaborator Vieregg on WBEZ's Afternoon Shift program. "It's great to watch the reaction of our community," Vieregg said during the interview. "Our website that has our data and papers on it has actually gotten three and a half million hits as of last night."

Read more >>

Related Links:
KICP Members: John E. Carlstrom; Christopher Sheehy; Michael S. Turner; Abigail Vieregg
Scientific projects: BICEP2/The Keck Array/BICEP3
 
Astrophysicists target mystery of powerful particles: Prof. Angela Olinto continues UChicago leadership in cosmic ray research with space station telescope
The University of Chicago News Office, March 20, 2014
Astrophysicists target mystery of powerful particles: Prof. Angela Olinto continues UChicago leadership in cosmic ray research with space station telescope
by Steve Koppes, The University of Chicago News Office

Every second, our bodies and the objects around us are struck by cosmic rays that come mostly from sources deep in space. The highest-energy cosmic rays are the most energetic particles in the universe - far more powerful than anything humans could produce - but their origins are a mystery.

University of Chicago astrophysicist Angela Olinto is helping to unravel that stubborn riddle by leading the United States collaboration on an international project to deploy a cosmic ray telescope on the International Space Station later this decade. The instrument will peer back at Earth to detect the collisions of cosmic rays with the atmosphere, which could shed light on what produces the enigmatic particles.

"This first space mission for the highest-energy particles may pioneer the space exploration of the Earth's atmosphere as a giant particle detector," wrote Olinto, the Homer J. Livingston Professor in Astronomy & Astrophysics, in Il Nuovo Saggiatore, an Italian science magazine.


This first space mission for the highest-energy particles may pioneer the space exploration of the Earth's atmosphere as a giant particle detector."
-Angela Olinto
Homer J. Livingston Professor in Astronomy & Astrophysics


Funded by a $4.4 million grant from NASA, Olinto and her colleagues are part of a 15-nation effort to build the 2.5-meter ultraviolet telescope, called the Extreme Universe Space Observatory.

No one knows what they will find. Ultra high-energy cosmic rays may come from supermassive black holes at the centers of nearby galaxies. A far less likely possibility is that they are decaying particles left over from the Big Bang. These subatomic particles hit the atmosphere with the energy of a tennis ball traveling at 167 miles an hour. The impact produces a giant cascade of many tens of billions of secondary particles, which to date have been observed only from Earth-based detectors.

"The mechanism behind this extreme acceleration challenges our imagination," Olinto says.

UChicago has a long history of research in cosmic rays, including more than half a century of balloon- and spacecraft-borne experiments conducted by scientists in the Enrico Fermi Institute. Austrian physicist Victor Hess discovered cosmic rays in 1912; surprisingly, he discovered that cosmic-ray intensity increased with altitude.

That chance discovery showcases "a beautiful aspect of science," says 1980 Nobel laureate James Cronin, University Professor Emeritus in Physics. "The discovery was that radiation is coming from outer space into Earth. One had no idea what this radiation was, but nevertheless it was there."

Clashing Nobel laureates
Originally called hohenstrahlung - German for "radiation from above" - the radiation has been known as cosmic rays since Robert A. Millikan coined the term in 1928. Millikan later would trade barbs with his former UChicago student and fellow Nobel laureate, Arthur Holly Compton, over their conflicting cosmic-ray data in a quarrel that made the front page of The New York Times.

"Millikan retorts hotly to Compton in cosmic ray clash," reported the Times on Dec. 31, 1932. Millikan, a UChicago faculty member from 1898 to 1921, asserted that cosmic rays consisted of gamma radiation. Compton, who was on the faculty from 1923 to 1945, believed that cosmic rays were charged particles. Compton was correct, but Millikan never did revise his opinion.

Cosmic rays pose little risk to organisms on Earth, where the atmosphere and the planet's magnetic field offer protection. But cosmic rays are a factor in the planning of extended interplanetary missions, where astronauts could be exposed to dangerous levels of radiation. The particles also can affect consumer electronics, causing subtle errors when they strike integrated circuits and other components.

The cosmic ray telescope that scientists hope to install aboard the space station will look down, to detect the giant particle cascades that high-energy cosmic rays produce when they enter Earth's atmosphere. The late Pierre Auger discovered this phenomenon in 1938. A few years later Auger continued his research during a visit to UChicago.

Cronin and his associates would spend years planning and establishing a sprawling cosmic ray observatory in Argentina that they named after Auger. The Pierre Auger Observatory began collecting data in 2004. "We have solved many open questions from the last century, but we didn't find the source of the highest-energy cosmic rays," Olinto says.

Despite its vast scale, the Auger Observatory can only detect subatomic particle interactions occurring in the atmosphere directly above its telescopes. But with the installation of a downward-looking ultraviolet telescope on the International Space Station, the entire atmosphere becomes a particle detector. The cosmic processes that produce those particles far exceed the capabilities of mankind's most powerful accelerator, the Large Hadron Collider in Switzerland. Space-based observations offer a way to overcome the constraints of man-made devices.

"In my opinion, it's the way to the future," Olinto says.

Coming full circle
With this approach, the study of cosmic rays and particle physics are coming full circle. "In the early part of the 20th century, cosmic ray research and particle physics were one and the same," notes Dietrich Muller, a professor emeritus in physics who has devoted much of his career to cosmic-ray research.

But cosmic ray research and particle physics went their separate ways in the 1950s. Scientists began building powerful particle accelerators, establishing the field of high-energy particle physics. "The other branch was to make measurements above the atmosphere, and that led to what's now called particle astrophysics, gamma-ray astronomy, and X-ray astronomy," Muller says.

In the meantime, the Telescope Array Project in Utah and the IceCube Neutrino Observatory at the South Pole have begun offering hints about the source of high-energy cosmic rays. Data from the Telescope Array has found a hotspot in the northern sky that indicates a possible source of ultra high-energy cosmic rays. IceCube also has found two neutrinos coming from that same region of the sky. Neutrinos - sometimes called ghost particles because of their ability to pass through solid matter - offer a second means of determining the source of high-energy cosmic rays.

The hotspot could be a temporary phenomenon that will disappear before the Extreme Observatory begins operating on the space station. "If it persists, then we should be able to confirm that this is the first source ever measured," Olinto says.

Read more >>

Related Links:
KICP Members: Angela V. Olinto
Scientific projects: Pierre Auger Observatory (AUGER)
 
First direct evidence of Big Bang found
WBEZ95.1, March 19, 2014
First direct evidence of Big Bang found
WBEZ95.1

Yesterday, scientists announced they have found the first direct evidence that right after the Big Bang, the universe expanded very far and very fast, in a fraction of a second. They call the process "cosmic inflation", and the discovery has incredible implications.


Abby Vieregg is an assistant professor at the University of Chicago, and part of the research team. She joins us to tell us more about this key scientific discovery and what it means for our understanding of the universe.

Read more >>

Related Links:
KICP Members: Abigail Vieregg
 
Telescope captures view of gravitational waves: Images of the infant Universe reveal evidence for rapid inflation after the Big Bang
Nature, March 18, 2014
by Ron Cowen, Nature

Astronomers have peered back to nearly the dawn of time and found what seems to be the long-sought 'smoking gun' for the theory that the Universe underwent a spurt of wrenching, exponential growth called inflation during the first tiny fraction of a second of its existence.

Using a radio telescope at the South Pole, the US-led team has detected the first evidence of primordial gravitational waves, ripples in space that inflation generated 13.8 billion years ago when the Universe first started to expand.

The telescope captured a snapshot of the waves as they continued to ripple through the Universe some 380,000 years later, when stars had not yet formed and matter was still scattered across space as a broth of plasma. The image was seen in the cosmic microwave background (CMB), the glow that radiated from that white-hot plasma and that over billions of years of cosmic expansion has cooled to microwave energies.

The fact that inflation, a quantum phenomenon, produced gravitational waves demonstrates that gravity has a quantum nature just like the other known fundamental forces of nature, experts say. Moreover, it provides a window into interactions much more energetic than are accessible in any laboratory experiment. In addition, the way that the team confirmed inflation is itself of major significance: it is the most direct evidence yet that gravitational waves - a key but elusive prediction of Albert Einstein's general theory of relativity - exist.

"This is a totally new, independent piece of cosmological evidence that the inflationary picture fits together," says theoretical physicist Alan Guth of the Massachusetts Institute of Technology (MIT) in Cambridge, who proposed the idea of inflation in 1980. He adds that the study is "definitely" worthy of a Nobel prize.

Instant inflation
Guth's idea was that the cosmos expanded at an exponential rate for a few tens of trillionths of trillionths of trillionths of seconds after the Big Bang, ballooning from subatomic to football size. Inflation solves several long-standing cosmic conundrums, such as why the observable Universe appears uniform from one end to the other. Although the theory has proved to be consistent with all cosmological data collected so far, conclusive evidence for it has been lacking.

Cosmologists knew, however, that inflation would have a distinctive signature: the brief but violent period of expansion would have generated gravitational waves, which compress space in one direction while stretching it along another (see 'Ripple effect'). Although the primordial waves would still be propagating across the Universe, they would now be too feeble to detect directly. But they would have left a distinctive mark in the CMB: they would have polarized the radiation in a curly, vortex-like pattern known as the B mode (see 'Cosmic curl').

Last year, another telescope in Antarctica - the South Pole Telescope (SPT) - became the first observatory to detect a B-mode polarization in the CMB (see Nature http://doi.org/rwt; 2013). That signal, however, was over angular scales of less than one degree (about twice the apparent size of the Moon in the sky), and was attributed to how galaxies in the foreground curve the space through which the CMB travels (D. Hanson et al. Phys. Rev. Lett. 111, 141301; 2013). But the signal from primordial gravitational waves is expected to peak at angular scales between one and five degrees.

And that is exactly what John Kovac of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, and his colleagues now say they have detected, using an instrument dubbed BICEP2 that is located just metres away from its competitor, the SPT.

Detecting the tiny B mode required measuring the CMB with a precision of one ten-millionth of a kelvin and distinguishing the primordial effect from other possible sources, such as galactic dust.

"The key question," says Daniel Eisenstein, an astrophysicist at the CfA, "is whether there could be a foreground that masquerades like this signal". But the team has all but ruled out that possibility, he says. First, the researchers were careful to point BICEP2 - an array of 512 superconducting microwave detectors - at the Southern Hole, a patch of sky that is known to contain only tiny amounts of such emissions. They also compared their data with those taken by an earlier experiment, BICEP1, and showed that a dust-generated signal would have had a different colour and spectrum.

Furthermore, data taken with a newer, more sensitive polarization experiment, the Keck array, which the team finished installing at the South Pole in 2012 and will continue operating for two more years, showed the same characteristics. "To see this same signal emerge from two other, different telescopes was for us very convincing," says Kovac.

"The details have to be worked out, but from what I know it's highly likely this is what we've all been waiting for," says astronomer John Carlstrom of the University of Chicago, Illinois, who is the lead researcher on the SPT. "This is the discovery of inflationary gravitational waves."

Solid signature
Cosmologist Marc Kamionkowski adds: "To me, this looks really, really solid." He was one of the first cosmologists to calculate what the signature of primordial gravitational waves should look like in the CMB. The findings are "on a par with dark energy, or the discovery of the CMB - something that happens once every several decades", says Kamionkowski, who is at Johns Hopkins University in Baltimore, Maryland.

The strength of the signal measured by BICEP2, although entirely consistent with inflation, initially surprised the researchers because it is nearly twice as large as estimated from previous experiments. According to theory, the intensity of a B-mode signal reveals how fast the Universe expanded during inflation, and therefore suggests the energy scale of the cosmos during that epoch. The data pinpoint the time when inflation occurred - about 10-37 seconds into the Universe's life - and its temperature at the time, corresponding to energies of about 1016 gigaelectronvolts, says cosmologist Michael Turner of the University of Chicago. That is the same energy at which three of the four fundamental forces of nature - the weak, strong and electromagnetic force - are expected to become indistinguishable from one another in a model known as the grand unified theory.

Because inflation took place in the realm of quantum physics, seeing gravitational waves arise from that epoch provides "the first-ever experimental evidence for quantum gravity", says MIT cosmologist Max Tegmark - in other words, it shows that gravity is at heart a quantum phenomenon, just like the other three fundamental forces. Physicists, however, have yet to fully understand how to reconcile general relativity with quantum physics from a theory standpoint.

The researchers reported the findings on 17 March at a press briefing at the CfA, held just after they described their results to scientists in a technical talk. The team also released several papers describing the results. In so doing, it seems to have beaten the SPT and also several other groups racing to find the fingerprint of inflation using an assortment of balloon-borne and ground-based experiments and one satellite, the European Space Agency's Planck spacecraft.

More-extensive maps of the B-mode polarization, and especially a full-sky survey, which the Planck telescope may be able to obtain later this year, should provide more clues about how inflation unfolded and what drove it. In addition to looking farther back in time than ever before, the discovery "is opening a window a trillion times higher in energy than we can access with the Large Hadron Collider", the world's premiere atom smasher, notes cosmologist Avi Loeb of the CfA, who is not part of the BICEP2 team.

Read more >>

Related Links:
KICP Members: John E. Carlstrom; Christopher Sheehy; Michael S. Turner; Abigail Vieregg
Scientific projects: BICEP2/The Keck Array/BICEP3
 
Space Ripples Reveal Big Bang's Smoking Gun
The New York Times, March 18, 2014
by Dennis Overbye, The New York Times

CAMBRIDGE, Mass. - One night late in 1979, an itinerant young physicist named Alan Guth, with a new son and a year's appointment at Stanford, stayed up late with his notebook and equations, venturing far beyond the world of known physics.

He was trying to understand why there was no trace of some exotic particles that should have been created in the Big Bang. Instead he discovered what might have made the universe bang to begin with. A potential hitch in the presumed course of cosmic evolution could have infused space itself with a special energy that exerted a repulsive force, causing the universe to swell faster than the speed of light for a prodigiously violent instant.

If true, the rapid engorgement would solve paradoxes like why the heavens look uniform from pole to pole and not like a jagged, warped mess. The enormous ballooning would iron out all the wrinkles and irregularities. Those particles were not missing, but would be diluted beyond detection, like spit in the ocean.

"SPECTACULAR REALIZATION," Dr. Guth wrote across the top of the page and drew a double box around it.

On Monday, Dr. Guth's starship came in. Radio astronomers reported that they had seen the beginning of the Big Bang, and that his hypothesis, known undramatically as inflation, looked right.

Reaching back across 13.8 billion years to the first sliver of cosmic time with telescopes at the South Pole, a team of astronomers led by John M. Kovac of the Harvard-Smithsonian Center for Astrophysics detected ripples in the fabric of space-time - so-called gravitational waves - the signature of a universe being wrenched violently apart when it was roughly a trillionth of a trillionth of a trillionth of a second old. They are the long-sought smoking-gun evidence of inflation, proof, Dr. Kovac and his colleagues say, that Dr. Guth was correct.

Inflation has been the workhorse of cosmology for 35 years, though many, including Dr. Guth, wondered whether it could ever be proved.

If corroborated, Dr. Kovac's work will stand as a landmark in science comparable to the recent discovery of dark energy pushing the universe apart, or of the Big Bang itself. It would open vast realms of time and space and energy to science and speculation.

Confirming inflation would mean that the universe we see, extending 14 billion light-years in space with its hundreds of billions of galaxies, is only an infinitesimal patch in a larger cosmos whose extent, architecture and fate are unknowable. Moreover, beyond our own universe there might be an endless number of other universes bubbling into frothy eternity, like a pot of pasta water boiling over.

'As Big as It Gets'
In our own universe, it would serve as a window into the forces operating at energies forever beyond the reach of particle accelerators on Earth and yield new insights into gravity itself. Dr. Kovac's ripples would be the first direct observation of gravitational waves, which, according to Einstein's theory of general relativity, should ruffle space-time.

Marc Kamionkowski of Johns Hopkins University, an early-universe expert who was not part of the team, said, "This is huge, as big as it gets."

He continued, "This is a signal from the very earliest universe, sending a telegram encoded in gravitational waves."

The ripples manifested themselves as faint spiral patterns in a bath of microwave radiation that permeates space and preserves a picture of the universe when it was 380,000 years old and as hot as the surface of the sun.

Dr. Kovac and his collaborators, working in an experiment known as Bicep, for Background Imaging of Cosmic Extragalactic Polarization, reported their results in a scientific briefing at the Center for Astrophysics here on Monday and in a set of papers submitted to The Astrophysical Journal.

Dr. Kovac said the chance that the results were a fluke was only one in 10 million.

Dr. Guth, now 67, pronounced himself "bowled over," saying he had not expected such a definite confirmation in his lifetime.

"With nature, you have to be lucky," he said. "Apparently we have been lucky."

The results are the closely guarded distillation of three years' worth of observations and analysis. Eschewing email for fear of a leak, Dr. Kovac personally delivered drafts of his work to a select few, meeting with Dr. Guth, who is now a professor at Massachusetts Institute of Technology (as is his son, Larry, who was sleeping that night in 1979), in his office last week.

"It was a very special moment, and one we took very seriously as scientists," said Dr. Kovac, who chose his words as carefully as he tended his radio telescopes.

Andrei Linde of Stanford, a prolific theorist who first described the most popular variant of inflation, known as chaotic inflation, in 1983, was about to go on vacation in the Caribbean last week when Chao-Lin Kuo, a Stanford colleague and a member of Dr. Kovac's team, knocked on his door with a bottle of Champagne to tell him the news.

Confused, Dr. Linde called out to his wife, asking if she had ordered anything.

"And then I told him that in the beginning we thought that this was a delivery but we did not think that we ordered anything, but I simply forgot that actually I did order it, 30 years ago," Dr. Linde wrote in an email.

Calling from Bonaire, the Dutch Caribbean island, Dr. Linde said he was still hyperventilating. "Having news like this is the best way of spoiling a vacation," he said.

By last weekend, as social media was buzzing with rumors that inflation had been seen and news spread, astrophysicists responded with a mixture of jubilation and caution.

Max Tegmark, a cosmologist at M.I.T., wrote in an email, "I think that if this stays true, it will go down as one of the greatest discoveries in the history of science."

John E. Carlstrom of the University of Chicago, Dr. Kovac's mentor and head of a competing project called the South Pole Telescope, pronounced himself deeply impressed. "I think the results are beautiful and very convincing," he said.

Paul J. Steinhardt of Princeton, author of a competitor to inflation that posits the clash of a pair of universes as the cause of genesis, said that if true, the Bicep result would eliminate his model, but he expressed reservations about inflation.

Lawrence M. Krauss of Arizona State and others also emphasized the need for confirmation, noting that the new results exceeded earlier estimates based on temperature maps of the cosmic background by the European Space Agency's Planck satellite and other assumptions about the universe.

"So we will need to wait and see before we jump up and down," Dr. Krauss said.

Corroboration might not be long in coming. The Planck spacecraft will report its own findings this year. At least a dozen other teams are trying similar measurements from balloons, mountaintops and space.

Spirals in the Sky
Gravity waves are the latest and deepest secret yet pried out of the cosmic microwaves, which were discovered accidentally by Arno Penzias and Robert Wilson at Bell Labs 50 years ago. They won the Nobel Prize.

Dr. Kovac has spent his career trying to read the secrets of these waves. He is one of four leaders of Bicep, which has operated a series of increasingly sensitive radio telescopes at the South Pole, where the thin, dry air creates ideal observing conditions. The others are Clement Pryke of the University of Minnesota, Jamie Bock of the California Institute of Technology and Dr. Kuo of Stanford.

"The South Pole is the closest you can get to space and still be on the ground," Dr. Kovac said. He has been there 23 times, he said, wintering over in 1994. "I've been hooked ever since," he said.

In 2002, he was part of a team that discovered that the microwave radiation was polarized, meaning the light waves had a slight preference to vibrate in one direction rather than another.

This was a step toward the ultimate goal of detecting the gravitational waves from inflation. Such waves, squeezing space in one direction and stretching it in another as they go by, would twist the direction of polarization of the microwaves, theorists said. As a result, maps of the polarization in the sky should have little arrows going in spirals.

Detecting those spirals required measuring infinitesimally small differences in the temperature of the microwaves. The group's telescope, Bicep2, is basically a giant superconducting thermometer.

"We had no expectations what we would see," Dr. Kovac said.

The strength of the signal surprised the researchers, and they spent a year burning up time on a Harvard supercomputer, making sure they had things right and worrying that competitors might beat them to the breakthrough.

A Special Time
The data traced the onset of inflation to a time that physicists like Dr. Guth, staying up late in his Palo Alto house 35 years ago, suspected was a special break point in the evolution of the universe.

Physicists recognize four forces at work in the world today: gravity, electromagnetism, and strong and weak nuclear forces. But they have long suspected that those are simply different manifestations of a single unified force that ruled the universe in its earliest, hottest moments.

As the universe cooled, according to this theory, there was a fall from grace, like some old folk mythology of gods or brothers falling out with each other. The laws of physics evolved, with one force after another splitting away.

That was where Dr. Guth came in.

Under some circumstances, a glass of water can stay liquid as the temperature falls below 32 degrees, until it is disturbed, at which point it will rapidly freeze, releasing latent heat.

Similarly, the universe could "supercool" and stay in a unified state too long. In that case, space itself would become imbued with a mysterious latent energy.

Inserted into Einstein's equations, the latent energy would act as a kind of antigravity, and the universe would blow itself up. Since it was space itself supplying the repulsive force, the more space was created, the harder it pushed apart.

What would become our observable universe mushroomed in size at least a trillion trillionfold - from a submicroscopic speck of primordial energy to the size of a grapefruit - in less than a cosmic eye-blink.

Almost as quickly, this pulse would subside, relaxing into ordinary particles and radiation. All of normal cosmic history was still ahead, resulting in today's observable universe, a patch of sky and stars billions of light-years across. "It's often said that there is no such thing as a free lunch," Dr. Guth likes to say, "but the universe might be the ultimate free lunch."

Make that free lunches. Most of the hundred or so models resulting from Dr. Guth's original vision suggest that inflation, once started, is eternal. Even as our own universe settled down to a comfortable homey expansion, the rest of the cosmos will continue blowing up, spinning off other bubbles endlessly, a concept known as the multiverse.

So the future of the cosmos is perhaps bright and fecund, but do not bother asking about going any deeper into the past.

We might never know what happened before inflation, at the very beginning, because inflation erases everything that came before it. All the chaos and randomness of the primordial moment are swept away, forever out of our view.

"If you trace your cosmic roots," said Abraham Loeb, a Harvard-Smithsonian astronomer who was not part of the team, "you wind up at inflation."

Read more >>

Related Links:
KICP Members: John E. Carlstrom; Christopher Sheehy; Abigail Vieregg
Scientific projects: BICEP2/The Keck Array/BICEP3
 
A big-bang theory gets a big boost: Evidence that vast cosmos was created in split second
The Washington Post, March 18, 2014
by Joel Achenbach, The Washington Post

In the beginning, the universe got very big very fast, transforming itself in a fraction of an instant from something almost infinitesimally small to something imponderably vast, a cosmos so huge that no one will ever be able to see it all.

This is the premise of an idea called cosmic inflation - a powerful twist on the big-bang theory - and Monday it received a major boost from an experiment at the South Pole called BICEP2. A team of astronomers led by John Kovac of the Harvard-Smithsonian Center for Astrophysics announced that it had detected ripples from gravitational waves created in a violent inflationary event at the dawn of time.

"We're very excited to present our results because they seem to match the prediction of the theory so closely," Kovac said in an interview. "But it's the case that science can never actually prove a theory to be true. There could always be an alternative explanation that we haven't been clever enough to think of."

The reaction in the scientific community was cautiously exultant. The new result was hailed as potentially one of the biggest discoveries of the past two decades.

Cosmology, the study of the universe on the largest scales, has already been roiled by the 1998 discovery that the cosmos is not merely expanding but doing so at an accelerating rate, because of what has been called "dark energy." Just as that discovery has implications for the ultimate fate of the universe, this new one provides a stunning look back at the moment the universe was born.

"If real, it's magnificent," said Harvard astrophysicist Lisa Randall.

Lawrence Krauss, an Arizona State University theoretical physicist, said of the new result, "It gives us a new window on the universe that takes us back to almost the very beginning of time, allowing us to turn previously metaphysical questions about our origins into scientific ones."

The measurement, however, is a difficult one. The astronomers chose the South Pole for BICEP2 and earlier experiments because the air is exceedingly dry, almost devoid of water vapor and ideal for observing subtle quirks in the ancient light pouring in from the night sky. They spent four years building the telescope, and then three years observing and analyzing the data. Kovac, 43, who has been to the South Pole 23 times, said of the conditions there, "It's almost like being in space."

The BICEP2 instrument sorts through the cosmic microwave background (CMB), looking for polarization of the light in a pattern that reveals the ripples of gravitational waves. The gravitational waves distort space itself, squishing and tugging the fabric of the universe. This is the first time that anyone has announced the detection of gravitational waves from the early universe.

There are other experiments by rival groups trying to detect these waves, and those efforts will continue in an attempt to confirm the results announced Monday.

"I would say it's very likely to be correct that we are seeing a signal from inflation," said Adrian Lee, a University of California at Berkeley cosmologist who is a leader of PolarBear, an experiment based on a mountaintop in Chile that is also searching for evidence of inflation. "But it's such a hard measurement that we really would like to see it measured with different experiments, with different techniques, looking at different parts of the sky, to have confidence that this is really a signal from the beginning of the universe."

The fact that the universe is dynamic at the grandest scale, and not static as it appears to be when we gaze at the "fixed stars" in the night sky, has been known since the late 1920s, when astronomer Edwin Hubble revealed that the light from galaxies showed that they were moving away from one another.

This led to the theory that the universe, once compact, is expanding. Scientists in recent years have been able to narrow down the age of the universe to about 13.8 billion years. Multiple lines of evidence, including the detection of the CMB exactly 50 years ago, have bolstered the consensus model of modern cosmology, which shows that the universe was initially infinitely hot and dense, literally dimensionless. There was no space, no time.

Then something happened. The universe began to expand and cool. This was the big bang.

Cosmic inflation throws gasoline on that fire. It makes the big bang even bangier right at the start. Instead of a linear expansion, the universe would have undergone an exponential growth.

In 1979, theorist Alan Guth, then at Stanford, seized on a potential explanation for some of the lingering mysteries of the universe, such as the remarkable homogeneity of the whole place - the way distantly removed parts of the universe had the same temperature and texture even though they had never been in contact with each other. Perhaps the universe did not merely expand in a stately manner but went through a much more dramatic, exponential expansion, essentially going from microscopic in scale to cosmically huge in a tiny fraction of a second.

It is unclear how long this inflationary epoch lasted. Kovac calculated that in that first fraction of a second the volume of the universe increased by a factor of 10 to the 26th power, going from subatomic to cosmic.

This is obviously difficult terrain for theorists, and the question of why there is something rather than nothing creeps into realms traditionally governed by theologians. But theoretical physicists say that empty space is not empty, that the vacuum crackles with energy and that quantum physics permits such mind-boggling events as a universe popping up seemingly out of nowhere.

"Inflation - the idea of a very big burst of inflation very early on - is the most important idea in cosmology since the big bang itself," said Michael Turner, a University of Chicago cosmologist. "If correct, this burst is the dynamite behind our big bang."

Princeton University astrophysicist David Spergel said after Monday's announcement, "If true, this has revolutionary impacts for our understanding of the physics of the early universe and gives us insight into physics on really small scales."

Spergel added, "We will soon know if this result is revolutionary or due to some poorly understood systematics."

The inflationary model implies that our universe is exceedingly larger than what we currently observe, which is humbling already in its scale. Moreover, the vacuum energy that drove the inflationary process would presumably imply the existence of a larger cosmos, or "multiverse," of which our universe is but a granular element.

"These ideas about the multiverse become interesting to me only when theories come up with testable predictions based on them," Kovac said Monday. "The powerful thing about the basic inflationary paradigm is that it did offer us this clear, testable prediction: the existence of gravitational waves which are directly linked to the exponential expansion that's intrinsic to the theory."

The cosmological models favored by scientists do not permit us to have contact with other potential universes. The multiverse is, for now, conjectural, because it is not easily subject to experimental verification and is unobservable - from the South Pole or from anywhere else.

Read more >>

Related Links:
KICP Members: Christopher Sheehy; Michael S. Turner; Abigail Vieregg
Scientific projects: BICEP2/The Keck Array/BICEP3
 
Case for Dark Matter Signal Strengthens
Quanta Magazine, Simons Foundation, March 6, 2014
by Natalie Wolchover, Quanta Magazine, Simons Foundation

Dan Hooper, Tracy Slatyer, Tim Linden and Stephen Portillo (shown clockwise from top left), and collaborators claim that the annihilation of dark matter particles called WIMPs is the only plausible source for the gamma-ray excess coming from the center of the galaxy.

Read more >>

Related Links:
KICP Members: Daniel Hooper; Tim Linden
 
Communicating Science with Alan Alda
The University of Chicago News Office, February 25, 2014
Communicating Science with Alan Alda
The University of Chicago News Office

Kavli Institute workshop helps scientists engage more clearly with reporters, philanthropists, policymakers and the public.

Related links:
YouTube | iTunes U

Read more >>
 
Faculty members recognized for research, teaching and professional service with new professorships
University of Chicago News Office, February 5, 2014
Angela Olinto, KICP senior member
Angela Olinto, KICP senior member
University of Chicago News Office

Angela Olinto, who has made important contributions to the physics of quark stars, inflationary theory, cosmic magnetic fields and particle astrophysics, has been named a Homer J. Livingston Professor in Astronomy & Astrophysics and the College.

Olinto's research interests span theoretical astrophysics, particle and nuclear astrophysics, and cosmology. She has focused much of her work on understanding the origins of the highest energy cosmic rays and the ultra-compressed core of matter in neutron stars. Ultra-high-energy cosmic rays enter the atmosphere with so much energy that they produce a giant cascade of many tens of billions of secondary particles, which can be observed by large detectors such as the Auger Observatory.

Last year, Olinto was elected a fellow of the American Association for the Advancement of Science for her distinguished contributions to the field of astrophysics, particularly exotic states of matter and extremely high-energy cosmic ray studies at the Pierre Auger Observatory in Argentina.

She also is a fellow of the American Physical Society and has received the Chaire d'Excellence Award of the French Agence Nationale de Recherche. Olinto also is a recipient of the University's highest teaching honor, the Llewellyn John and Harriet Manchester Quantrell Award for Excellence in Undergraduate Teaching.

A faculty member at UChicago since 1996, Olinto now leads the U.S. collaboration of the Japanese Experiment Module-Extreme Universe Space Observatory mission to observe these ultra-energy particles from the International Space Station.

Read more >>

Related Links:
KICP Members: Angela V. Olinto
Scientific projects: Pierre Auger Observatory (AUGER)
 
Joshua Frieman has been awarded an Honorary Fellowship of the Royal Astronomical Society
Royal Astronomical Society, January 10, 2014
Joshua Frieman has been awarded an Honorary Fellowship of the Royal Astronomical Society
Royal Astronomical Society

Professor Joshua Frieman, Professor of Astronomy and Astrophysics at the University of Chicago, and member of the Theoretical Astrophysics group at Fermilab. Freiman's research centres on theoretical and observational cosmology, including studies of the nature of dark energy, the early Universe, gravitational lensing, the large-scale structure of the Universe, and supernovae as cosmological distance indicators. He is a founder of and currently serves as Director of the Dark Energy Survey, a collaboration of over 120 scientists from 20 institutions on 3 continents. Honorary Fellowship is conferred to mark his singular contributions to the study of dark energy.

Read more >>

Related Links:
KICP Members: Joshua A. Frieman
Scientific projects: Dark Energy Survey (DES)
 
On the dark side
University of Chicago Magazine, December 19, 2013
Josh Frieman, PhD'89, captures light from, and shines light on, the mysterious dark universe. (Photography by Drew Reynolds)
Josh Frieman, PhD'89, captures light from, and shines light on, the mysterious dark universe. (Photography by Drew Reynolds)
by Maureen Searcy, University of Chicago Magazine

Astrophysicist Josh Frieman, PhD'89, works on the dark side, studying the night sky for insight into the accelerating expansion of the universe.

Josh Frieman, PhD'89, will spend the next five years photographing the night sky with a really big camera. In August the 570-megapixel Dark Energy Camera, built at Fermilab and mounted on the Victor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile, began taking about 400 images of the southern sky every night. Each image captures the light of approximately 100,000 distant galaxies. The project, the Dark Energy Survey, is the largest-yet extragalactic survey and will record information on more than 300 million galaxies. Led by Frieman, UChicago professor of astronomy and astrophysics and Fermilab staff scientist, the survey enlists more than 200 scientists from 25 organizations.

The main goal of the survey is to understand why the expansion of the universe is speeding up: whether a mysterious dark energy pervades the universe or if something is amiss with the law of gravity on cosmic scales. To that end, it is measuring the history of cosmic expansion, or how fast the universe is expanding today compared to its rate billions of years ago. The survey is also measuring the history of large-scale structures: organizations of cosmic elements like clusters of galaxies, superclusters, and filaments. Galaxies tend to clump together, but the strength of that tendency changes over time. "There's this competition between gravity" - particularly the gravity of dark matter - "which is making galaxies attract to each other, and dark energy, which is pushing them apart," Frieman says. Studying this competition and the historical rates of expansion should explain more about the properties of dark energy.

Trained as a theoretical cosmologist, Frieman has worked increasingly with survey data. He previously led the Sloan Digital Sky Survey (SDSS-II) Supernova Survey, a three-year project that discovered and measured more than 500 type Ia supernovae-exploding stars that grow as bright as an entire galaxy for a short time and can be used to measure cosmic distances. Frieman is struck, he says, by the knowledge that can be gained by simply looking at the sky. "What's remarkable to me is that just by taking pictures, we can learn so much about how the universe has evolved." In an interview with the Magazine, adapted and edited below, he talked about the cosmos scientifically and philosophically.

Origins
It really wasn't until I was in college at Stanford that I caught fire with cosmology. An eminent cosmologist from Oxford, Dennis Sciama, came and gave a colloquium on the history of the universe. That was eye-opening to me, the notion that cosmology, in a way, was like archaeology on the grand scale, and that we could use the observed universe, galaxies and how they're distributed in space, similarly to how pottery shards are used by an archaeologist, to figure out what the universe looked like billions of years ago.

In the dark
We don't know what dark matter is, but we know that it obeys the ordinary laws of gravity - or we think it does. So there are experiments going on to try to detect particles of dark matter, since that's one of the leading ideas of what dark matter could be. It could just be clouds of elementary particles zipping around. Dark energy - we call them both dark because they don't emit or interact with light - is something much stranger, and it would make up about 70 percent of the universe. Unlike dark matter, it doesn't hold stuff together. Dark energy pushes stuff apart.

Filled with emptiness
One idea for what dark energy could be is the energy of empty space. If you imagine taking this coffee cup, well, it's kind of dirty, but it's filled with molecules of air, right? And imagine I sealed it, attached it to a pump to a vacuum and pumped out all of the particles that were there. It would be totally empty space. In classical physics, if there are no particles in there, there's no energy. But according to the laws of quantum mechanics, even if there are no particles in there, empty space itself can still have energy.

Before the beginning
Currently the laws of physics can take us back very close to the big bang - a tiny fraction of a second, we think, after the big bang. There is strong evidence that the early universe was very hot and very dense, and that's really what we should call the big bang. Now whether we trace that back to a single point in time, and whether it traces back somehow beyond that point in time, that becomes much more speculative because the laws of physics break down before we get there. And then there comes this question of what do we even mean by time when we get to this point? Because our classical notions of space and time themselves break down. There are certainly physicists who have worked on theories of "what happens before the big bang," ideas that before the big bang, maybe there was a previous universe that contracted and then bounced and led to the current expansion. That's certainly possible. It may be possible to theorize about that in a consistent way given the laws of physics, but at this point it's very speculative.

Where we are
Copernicus showed that we are not at the center of the universe. Now with Hubble and others, we know that not only is the sun not at the center of the universe, the sun is just one of tens of billions of stars in this rather ordinary galaxy that's one of billions of galaxies that are flying apart from each other due to the expansion of the universe. So in fact there is no center of the universe. And now with dark matter and dark energy, we're not even made of the stuff that most of the universe is made of. It's like we're this little spray on the big ocean of the universe.

Star stuff
On the other hand, I think what counters that is the sense that there's a real unity to the cosmos. I find some strange comfort in the fact that we're all made of stuff that was produced in the supernovae. Most of the elements in our bodies and that we construct the world out of were forged in nuclear reactions in stars when they exploded, and then were spread throughout space. So we actually have this very strange, very direct physical connection to this universe that we're studying. And the fact that we've been able to evolve and develop technologies to understand that universe doesn't give us power over the universe, but I think for me, there's comfort in that understanding of how we got here.

Read more >>

Related Links:
KICP Members: Joshua A. Frieman
Scientific projects: Dark Energy Survey (DES)
 
Swirls in remnants of Big Bang may hold clues to universe's infancy
University of Chicago News, December 13, 2013
Physics Review magazine has named research results published earlier this year by the South Pole Telescope collaboration as one of the top 10 physics breakthroughs of 2013.
Physics Review magazine has named research results published earlier this year by the South Pole Telescope collaboration as one of the top 10 physics breakthroughs of 2013.
by Emily Conover, University of Chicago News

South Pole Telescope scientists have detected for the first time a subtle distortion in the oldest light in the universe, which may help reveal secrets about the earliest moments in the universe's formation.

The scientists observed twisting patterns in the polarization of the cosmic microwave background-light that last interacted with matter very early in the history of the universe, less than 400,000 years after the Big Bang. These patterns, known as "B modes," are caused by gravitational lensing, a phenomenon that occurs when the trajectory of light is bent by massive objects, much like a lens focuses light.

Early today, Physics World magazine heralded the result as one of the top 10 physics breakthroughs of 2013.

A multi-institutional collaboration of researchers led by John Carlstrom, the S. Chandrasekhar Distinguished Service Professor in Astronomy & Astrophysics at the University of Chicago, made the discovery. They announced their findings in a paper published in the journal Physical Review Letters-using the first data from SPTpol, a polarization-sensitive camera installed on the telescope in January 2012.

"The detection of B-mode polarization by South Pole Telescope is a major milestone, a technical achievement that indicates exciting physics to come," Carlstrom said.

The cosmic microwave background is a sea of photons (light particles) left over from the Big Bang that pervades all of space, at a temperature of minus 270 degrees Celsius-a mere 3 degrees above absolute zero. Measurements of this ancient light have already given physicists a wealth of knowledge about the properties of the universe. Tiny variations in temperature of the light have been painstakingly mapped across the sky by multiple experiments, and scientists are gleaning even more information from polarized light.

Light is polarized when its electromagnetic waves are preferentially oriented in a particular direction. Light from the cosmic microwave background is polarized mainly due to the scattering of photons off of electrons in the early universe, through the same process by which light is polarized as it reflects off the surface of a lake or the hood of a car. The polarization patterns that result are of a swirl-free type, known as "E modes," which have proven easier to detect than the fainter B modes, and were first measured a decade ago by a collaboration of researchers using the Degree Angular Scale Interferometer, another UChicago-led experiment.

Simple scattering can't generate B modes, which instead emerge through a more complex process-hence scientists' interest in measuring them. Gravitational lensing, it has long been predicted, can twist E modes into B modes as photons pass by galaxies and other massive objects on their way toward earth. This expectation has now been confirmed.

To tease out the B modes in their data, the scientists used a previously measured map of the distribution of mass in the universe to determine where the gravitational lensing should occur. They combined their measurement of E modes with the mass distribution to provide a template of the expected twisting into B modes. The scientists are currently working with another year of data to further refine their measurement of B modes.

The careful study of such B modes will help physicists better understand the universe. The patterns can be used to map out the distribution of mass, thereby more accurately defining cosmologically important properties like the masses of neutrinos, tiny elementary particles prevalent throughout the cosmos.

Similar, more elusive B modes would provide dramatic evidence of inflation, the theorized turbulent period in the moments after the Big Bang when the universe expanded extremely rapidly. Inflation is a well-regarded theory among cosmologists because its predictions agree with observations, but thus far there is not a definitive confirmation of the theory. Measuring B modes generated by inflation is a possible way to alleviate lingering doubt.

"The detection of a primordial B-mode polarization signal in the microwave background would amount to finding the first tremors of the Big Bang," said the study's lead author, Duncan Hanson, a postdoctoral scientist at McGill University in Canada.

B modes from inflation are caused by gravitational waves. These ripples in space-time are generated by intense gravitational turmoil, conditions that would have existed during inflation. These waves, stretching and squeezing the fabric of the universe, would give rise to the telltale twisted polarization patterns of B modes. Measuring the resulting polarization would not only confirm the theory of inflation - a huge scientific achievement in itself - but would also give scientists information about physics at very high energies - much higher than can be achieved with particle accelerators.

The measurement of B modes from gravitational lensing is an important first step in the quest to measure inflationary B modes. In inflationary B mode searches, lensing B modes show up as noise. "The new result shows that this noise can be accounted for and subtracted off so that scientists can search for and hopefully measure the inflationary B modes underneath," Hanson said. "The lensing signal itself can also be used by itself to learn about the distribution of mass in the universe."

Read more >>

Related Links:
KICP Members: John E. Carlstrom
Scientific projects: South Pole Telescope (SPT)
 
SPT's measurement of B-mode polarization chosen as one of Physics World's Top Ten Breakthroughs of 2013
Physics World news, December 13, 2013
SPT's measurement of B-mode polarization chosen as one of Physics World's Top Ten Breakthroughs of 2013
Physics World news

The award citation says: "To astronomers working on the South Pole Telescope for being the first to measure B-mode polarization in the cosmic microwave background radiation."

The IceCube collaboration may have bagged the Physics World 2013 Breakthrough of the Year award, but another discovery from the South Pole also makes it into our top-10 list. It is for the first detection of a subtle twist in light from the cosmic microwave background (CMB), known as B-mode polarization. This twist has long been predicted and its detection paves the way for a definitive test of inflation - a key theory in the Big Bang model of the universe.

The top ten was chosen by a panel of Physics World news editors and reporters using the following criteria:
Fundamental importance
Significant advance in knowledge
Strong connection between theory and experiment
General interest to all physicists

Read more >>

Related Links:
KICP Members: John E. Carlstrom
Scientific projects: South Pole Telescope (SPT)
 
Obituary: Fred Kavli, Founder and Chairman of The Kavli Foundation
The Kavli Foundation, November 22, 2013
Fred Kavli, Founder and Chairman of The Kavli Foundation
Fred Kavli, Founder and Chairman of The Kavli Foundation
The Kavli Foundation

Fred Kavli, founder and chairman of The Kavli Foundation, passed away peacefully on Thursday, November 21, in his home in Santa Barbara at the age of 86.

A philanthropist, physicist, entrepreneur, business leader and innovator, Fred Kavli established The Kavli Foundation to advance science for the benefit of humanity. Based in Southern California, the Foundation today includes an international community of basic research institutes in the fields of astrophysics, nanoscience, neuroscience, and theoretical physics. Located on three continents, the institutes are home to some of the most renowned researchers in their fields. The Foundation has also established and supported an international program of conferences, symposia, endowed professorships, and other activities. This includes being a founding partner of the biennial Kavli Prizes, which recognize scientists for their seminal advances in three research areas: astrophysics, nanoscience, and neuroscience.

Kavli began the Foundation in 2000 after divesting his interests in the Kavlico Corporation - a company that he founded and operated as the CEO and sole shareholder, and which became one of the world's largest suppliers of sensors for aeronautic, automotive and industrial applications.

"This is a painful loss for the Foundation and for all of science," said Rockell N. Hankin, Vice Chairman of the Foundation. "We can only take comfort in his extraordinary legacy, which will continue advancing critically important research that benefits all of humanity, and supports scientific work around the globe."

Said Robert W. Conn, President of the Foundation, "We will forever be grateful to Fred Kavli - someone who, with the Foundation, invested his heart and soul into ensuring that science will make this a better world for future generations. And we will carry forward this mission with the same commitment and dedication that he gave to science and his life."

About Fred Kavli
A naturalized American citizen, Kavli was born in 1927 on a small farm in Eresfjord, Norway - a village nestled in the mountains along the Eira River. Kavli would later recall these early days as giving birth to his interest in science, which would blossom further while studying physics at the Norwegian Institute of Technology (now known as the Norwegian University of Science and Technology in Trondheim). Building his business acumen, Kavli financed his studies with proceeds from a small business he and his brother, both teenagers, ran during World War II, making wood briquettes that could be used as fuel for modified automobiles. Immediately upon completing his studies in 1955 and receiving an engineering degree, he left for Canada and one year later came to the United States. After two years in California, he built upon his entrepreneurial spirit and experience and founded the Kavlico Corporation in Los Angeles in 1958 - later relocated to Moorpark, California. Under his leadership, the company would become one of the world's largest suppliers of sensors for aeronautical, automotive and industrial applications with its products found in such landmark projects as the SR-71 Blackbird and the Space Shuttle.

The company would receive many distinguished awards under Kavli's leadership and patent numerous technological breakthroughs. He remained CEO and sole shareholder of the company until the company was sold in 2000. He subsequently established The Kavli Foundation to support scientific research aimed at improving the quality of life for people around the world.

Over time, the Foundation has established and endowed research institutes at leading universities worldwide, focusing on the areas of astrophysics, nanoscience, neuroscience and theoretical physics. Today, there are seventeen such institutes and there will be more in the years to come. The Foundation has endowed research institutes in neuroscience at Columbia University, Yale University, the University of California, San Diego and the Norwegian University of Science and Technology; in nanoscience, there are Kavli Institutes at the California Institute of Technology, Cornell University, Harvard University, the Delft University of Technology, and the University of California, Berkeley; in astrophysics and cosmology, the institutes are at Stanford University, the University of Chicago, Massachusetts Institute of Technology, the University of Cambridge, Peking University, the University of Tokyo; and in theoretical physics, the institutes are at the University of California, Santa Barbara and the Chinese Academy of Sciences. The Foundation has also endowed seven university professorial chairs, sponsors science symposia and workshops, supports initiatives to engage the public in science and that help scientists themselves be better communicators, and supports excellence in science journalism. This includes endowing the AAAS Kavli Science Journalism Awards administered by the American Association for the Advancement of Science.

Starting in 2008, the Foundation launched a series of science prizes to recognize scientists for their seminal advances in astrophysics, nanoscience and neuroscience. Consisting of a scroll, a gold medal and a cash award of one million dollars, a Kavli Prize in each of these areas is awarded every two years. The Kavli Prizes are presented by the King of Norway in a ceremony in Oslo, Norway and are a partnership between The Kavli Foundation, the Norwegian Academy of Science and Letters, and the Norwegian Ministry of Education and Research. In acknowledgement of their achievement, U.S. laureates have been consistently invited to meet the President in the Oval Office in recognition of the importance of science in achieving a better and more prosperous society.

In addition to establishing institutes and prizes, the Foundation has brought together scientists at meetings that facilitate open dialogue and an exchange of ideas. These meetings have precipitated such major initiatives as the Brain Activity Map proposal, which was a major catalyst for President Obama's Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative announced in April 2013.

During his lifetime, Fred Kavli was a Fellow of the American Academy of Arts and Sciences, a member of the Norwegian Academy of Technological Sciences, and a member of the U.S. President's Council of Advisors on Science and Technology. A member of the University of California President's Board on Science and Innovation, he was a Trustee of the University of California, Santa Barbara (UCSB) Foundation. His many honors included receiving the Royal Norwegian Order of Merit for Outstanding Service and honorary doctorates from the Norwegian University of Science and Technology, Northwestern University, and the University of Oslo. In 2011 he received the Bower Award for Business Leadership from the Franklin Institute, one of the oldest science education centers in the United States, and the Carnegie Medal of Philanthropy, which is given biennially to one or more individuals who, like Andrew Carnegie, have dedicated their private wealth to public good, and who have sustained impressive careers as philanthropists.

In addition to supporting scientific research and education, Kavli's philanthropic activities included the Fred Kavli Theatre for Performing Arts at the Thousand Oaks Civic Arts Plaza, as well as other projects.

Fred Kavli contracted cholangiocarcinoma, a rare form of cancer, about a year ago and succumbed to complications due to surgeries. He is survived by two children, and nine nephews and nieces.

The family has issued this statement:
"In this moment of grief and deep personal loss, we thank everyone for their kind words and support, and for respecting our need for privacy.

"Fred has always been the anchor and gathering force for our family. He has been an inspiration and someone for us to look up to. We cherish the fond memories of our times together and we give our thanks for all he has done for us. He will be dearly missed.

"We can all reflect upon his example of giving so much of himself to make this world a better place. May his legacy continue to benefit mankind."

Read more >>
 
Dark Matter Experiment Has Detected Nothing, Researchers Say Proudly
The New York Times, November 5, 2013
Inside the Large Underground Xenon dark matter detector.  <i>Image cradit: Matthew Kapust/South Dakota Science and Technology Authority</i>
Inside the Large Underground Xenon dark matter detector.

Image cradit: Matthew Kapust/South Dakota Science and Technology Authority
by Dennis Overbye, The New York Times

But afterward, Juan I. Collar, a dark matter specialist at the University of Chicago who has been urging the community to take low-mass WIMPs seriously, questioned whether the LUX detector had been adequately calibrated to detect them.

"They do have a real interest in performing those calibrations, because they would settle the issue," Dr. Collar said in an email. "We just have to be patient. At the end they promised to do so, and I have no doubts they will."

Read more >>

Related Links:
KICP Members: Juan I. Collar
 
South Pole Telescope helps Argonne scientists study earliest ages of the universe
Argonne National Laboratory, November 5, 2013
Clarence Chang, KICP Senior Researcher
Clarence Chang, KICP Senior Researcher
by Louise Lerner, Argonne National Laboratory

For physicist Clarence Chang at the U.S. Department of Energy's (DOE) Argonne National Laboratory, looking backward in time to the earliest ages of the universe is all in a day's work.

Chang helped design and operate part of the South Pole Telescope, a project that aims a giant telescope at the night sky to track tiny bits of radiation that are still traveling across the universe from the period just after it was born.

"Basically, what we're looking at is the afterglow light of the Big Bang," Chang said.

In the wake of the Big Bang, all the matter in the universe was just hot, dense particles and light. As the universe got older, it began to spread out and cool down over time, and the intense light from that period traveled across space. It's still traveling, hitting us all the time, and it has a very distinct radiation signature. "We call this the Cosmic Microwave Background, and it is essentially a snapshot of the universe as it looked about 400,000 years after the Big Bang," Chang said.

There's still a lot we don't know about the makeup of the early universe. Particularly mysterious are the dark matter and dark energy that appear to make up 95% of the universe, but about which we know very little. Mapping the Cosmic Microwave Background can shed some light on these dark forms.

"The Cosmic Microwave Background photons have traveled so far in time that some of them bumped into the early galaxy clusters along the way," Chang said. "You can detect this because they get kicked around a bit, which changes the radiation signature."

This is useful because one of the things we do know about dark energy is that it affects how galaxy clusters form. Being able to compare the distribution of distant galaxy clusters with the distribution we observe nearby helps physicists decode the role dark energy played - and continues to play - in the universe.

The majority of the Cosmic Microwave Background radiation has wavelengths of just one to two millimeters. These photons are absorbed by water, so in order to catch them, you need a very dry, flat and preferably cold space, which narrows it down to just two locations on Earth. One is the Chilean mountains, where we have a different sky mapping project underway, and the other is the South Pole.

The South Pole telescope is more than 30 feet across; Chang and colleagues at Argonne helped build its camera. ("We had to build the camera ourselves, because no sane person needs a camera that sees down to wavelengths at millimeter length," he said.) He is part of a rotation that travels to the Pole for weeks at a time to check how the camera is functioning and perform maintenance.

Developing and designing the detectors for the camera required expertise from multiple Argonne facilities and research divisions, including the Center for Nanoscale Materials.

At the core of the detector technology is an extremely thin superconducting film. Although superconductors can carry an electrical charge perfectly, they are exquisitely sensitive to changes in temperature. When thermal radiation from the Cosmic Microwave Background hits the camera, it heats the material up slightly, which changes the conductivity of the film. This lets physicists record the energy coming from that particular part of the sky.

"So far we've mapped about 2,500 square degrees of the sky," he said, "so there's just 37,500 to go."

The South Pole telescope is funded through the National Science Foundation and the DOE's Office of Science. The other institutions in the partnership are the University of Chicago, the University of California at Berkeley, Case Western Reserve University, the Harvard-Smithsonian Center for Astrophysics, McGill University, the University of Colorado at Boulder and the University of California at Davis.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.

Read more >>

Related Links:
KICP Members: Clarence L. Chang
Scientific projects: South Pole Telescope (SPT)
 
UC Berkeley, Berkeley Lab announce Kavli Energy NanoSciences Institute
Kavli Foundation News, October 3, 2013
Kavli Foundation News

Berkeley - The Kavli Foundation has endowed a new institute at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory (Berkeley Lab) to explore the basic science of how to capture and channel energy on the molecular or nanoscale, with the potential for discovering new ways of generating energy for human use.

The Kavli Energy NanoSciences Institute (Kavli ENSI), announced today (Thursday, Oct. 3), will be supported by a $20 million endowment, with The Kavli Foundation providing $10 million and UC Berkeley raising equivalent matching funds. The Kavli Foundation will also provide additional start-up funds for the institute. The Kavli ENSI will explore fundamental issues in energy science, using cutting-edge tools and techniques developed to study and manipulate nanomaterials - stuff with dimensions a thousand times smaller than the width of a human hair - to understand how solar, heat and vibrational energy are captured and converted into useful work by plants and animals or novel materials.

This new Kavli Institute has already received matching fund gifts from the Heising-Simons Foundation, establishing a Heising-Simons Energy Nanoscience Fellows program, and a donation from the Philomathia Foundation, establishing the Philomathia Discovery Fund.

"The field of nanoscience is poised to change the very foundations of how we should think about future energy conversion systems," said Kavli ENSI Director Paul Alivisatos, who is also director of Berkeley Lab and the Samsung Distinguished Chair in Nanoscience and Nanotechnology in UC Berkeley's College of Chemistry. "UC Berkeley and Berkeley Lab stand out worldwide for their strong efforts in nanoscience and their research activities related to energy, so energy nanoscience is a particular strength for us."

"I am delighted to welcome the Kavli ENSI into the community of Kavli institutes," said Fred Kavli, Founder and Chairman of The Kavli Foundation. "By exploring the basic science of energy conversion in biological systems, as well as building entirely new hybrid and perhaps even completely artificial systems, the Kavli ENSI is positioned to revolutionize our thinking about the science of energy, and is positioned to do the kind of basic research that will ultimately make this a better world for all of us."

"This new partnership with the Kavli Foundation and the Berkeley Lab is significant and exciting," said UC Berkeley Chancellor Nicholas Dirks. "The Kavli Institute will expand our portfolio of research endeavors focused on alternative sources of energy, one of the planet's most pressing and complicated challenges. Progress in the realm of energy nanosciences will be contingent on successful collaboration across conventional scientific boundaries - the very approach that has made Berkeley a global leader in alternative energy research."

"There is simply no better time, given the issues surrounding energy worldwide, to announce an institute dedicated to the basic science of energy. This new Kavli Institute will have superb leadership and a large number of extraordinary faculty affiliated with it," said Robert W. Conn, President of The Kavli Foundation. "I'd like as well to thank both the Heising-Simons Foundation and the Philomathia Foundation for their confidence in Berkeley and in this new Kavli Institute. Their matching gifts will help the Kavli ENSI at Berkeley get off to a very strong start." He added, "There is also no more important time than now to invest in basic scientific research. History has shown that discoveries in basic science have a profound impact on the economy of nations, on the health of people, and on the well-being of societies."

The Kavli ENSI will be the fifth nanoscience institute established by The Kavli Foundation, joining Kavli Institutes at the California Institute of Technology, Cornell University, Delft University of Technology in the Netherlands and Harvard University. The Foundation funds an international program that includes research institutes, professorships, symposia and other initiatives in the four fields of astrophysics, nanoscience, neuroscience and theoretical physics. The foundation is also a founder of the Kavli Prizes, which recognize scientists for their seminal advances in astrophysics, nanoscience and neuroscience.

With the announcement of the Kavli ENSI, The Kavli Foundation has established seventeen institutes worldwide - 11 in the United States, three in Europe and three in Asia.

Scientists at the Kavli Energy NanoSciences Institute will look beyond today's energy conversion approaches to explore unusual avenues found in biological systems and to build entirely new hybrid or completely artificial systems. For example, Kavli ENSI scientists plan to explore how plant pigments capture energy from the sun and transport this energy for chemical storage, and how the body's molecular motors convert chemical energy into motion inside a cell. Meanwhile, other scientists and engineers plan to build nanodevices that mimic and improve on nature's tricks, using materials ranging from graphene and metal oxide frameworks to nanowires and nanolasers.

The campus and laboratory boast a long history of nanoscience innovation, starting with Alivisatos' work in the science of nanocrystals, ranging from studies of their physical properties to synthesis and applications in biological imaging and renewable energy. Nearly 100 research labs are devoted to aspects of nanoscience and nanoengineering.

"The new Kavli ENSI institute is intended to allow us to explore the principles of energy systems on small scales and is not focused on any particular area of application," Alivisatos emphasized. "Fred Kavli's vision is to support curiosity-driven science. This institute will help to foster a long term perspective."

"Of course, we have all learned that innovative solutions to pressing problems can often start in the basic sciences," said institute co-director Omar Yaghi, the James and Neeltje Tretter Chair and professor of chemistry at UC Berkeley and a Berkeley Lab researcher. Yaghi's work on the nanoscale properties of metal oxide frameworks - porous composites of iron and organic molecules - proved to have wide application in natural gas and hydrogen storage and carbon capture.

Alivisatos said that much of today's energy research focuses on improving well-known technologies, such as batteries, liquid fuels, solar cells and wind generators. On the nanoscale, however, energy is captured, channeled and stored in totally different ways dictated by the quantum mechanical nature of small-scale interactions.

"We don't fully understand some foundational issues about how energy is converted to work on really short length scales," he said.

Research by UC Berkeley and Berkeley Lab chemist Graham Fleming has shown, for example, that when leaf pigments capture light in the form of photons, electrons are excited and interact in a coherent way not seen at larger scales. This quantum coherence could potentially be incorporated into nanoscale artificial systems to produce energy on a commercial scale.

While studying nanoscale motors inside cells, UC Berkeley physicist Carlos Bustamante and Berkeley Lab theorist Gavin Crooks discovered that energy flow does not always follow the standard rules of macroscopic systems. Nanomotors can sometimes move backward, for example, akin to a ball rolling uphill. Such quantum weirdness might be replicated to create more efficient nanomachines or self-regulating nanoscale energy circuits.

Other Kavli ENSI scientists plan to investigate how heat flows in nanomaterials and whether the vibrational energy, or phonons, can be channeled to make thermal rectifiers, diodes or transistors analogous to electronic switches in use today; develop novel materials, ranging from polymers to cage structures and nanowires, with unusual nanoscale properties; or design materials that could sort, count and channel molecules along prescribed paths and over diverse energy landscapes to carry out complex chemical conversions.

"I think that by bringing together people who make new forms of matter, others who know how to manipulate matter on a fine scale, and those who try to understand how electrons or light propagate through these materials, we will get the kind of out-of-the-box thinking from which whole new areas of research emerge," Yaghi said.

Institute co-director Peidong Yang, the S.K. and Angela Chan Distinguished Professor of Energy in the College of Chemistry, said that Kavli ENSI's multidisciplinary, intellectually stimulating environment will be ideal for learning "how to program the assembly of nanoscopic building blocks, to create the necessary interfaces so that energy flow, molecular and charge-charge transport can be controlled in a cooperative manner."

While the institute will not have separate lab space, its administrative offices will be housed in two new buildings expected to be completed next year: Campbell Hall on the UC Berkeley campus and the Solar Energy Research Center at Berkeley Lab.

The Philomathia Discovery Fund operating within the Kavli ENSI will support research projects that have exceptional promise to deliver fundamental conceptual and technical breakthroughs. This Discovery Fund is made possible by a matching gift from the Philomathia Foundation, which was founded to promote human values and science through education and research.

The Heising-Simons Energy Nanoscience Fellows Program will establish a named fellowship to provide support for outstanding graduate students, postdocs or early-career faculty who are performing research affiliated with the Kavli Institute. This fellowship is made possible by a matching gift from the Heising-Simons Foundation, which supports efforts in education, environment, science and public policy.

The Kavli Foundation, dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research and supporting scientists and their work, was founded in 2000 by physicist Fred Kavli, the founder, former chairman and former chief executive officer of Kavlico Corporation in Moorpark, Calif., a supplier of sensors for aeronautics, automotive and industrial applications.

Media contacts:
Robert Sanders, UC Berkeley: rlsandersberkeley.edu, (510) 643-6998
Lynn Yarris, Berkeley Lab: lcyarrislbl.gov, (510) 486-5375
James Cohen, The Kavli Foundation: cohenkavlifoundation.org, (805) 278-7495

Read more >>
 
The Dark Energy Camera
Chicago Tonight, September 27, 2013
The Dark Energy Camera
by Eddie Arruza, Chicago Tonight

It's the world's most powerful digital camera and it sits atop the Blanco telescope in the Andes Mountains of Chile. But it was constructed on the campus of Fermilab in far west suburban Batavia. The Dark Energy Camera officially began its work on August 31 and has already captured some amazing images of outer space. Its real mission, though, is to help scientists figure out if so-called Dark Energy is responsible for the universe's accelerating expansion. We learn how the camera is helping scientists unravel one of the greatest mysteries in the cosmos. View a slideshow of photos taken by the Dark Energy Camera.

Members of the Dark Energy Survey collaboration explain what they hope to learn by studying the southern sky with the world's most advanced digital camera in the following video.

Read more >>

Related Links:
KICP Members: Joshua A. Frieman
Scientific projects: Dark Energy Survey (DES)
 
Giant digital camera probes cosmic 'dark energy,' the universe's deepest mystery
The Washington Post, September 11, 2013
Technicians installed the $50 million Dark Energy Camera atop a telescope in Chile last year. <i>Image credit: Reidar Hahn/Fermilab</i>
Technicians installed the $50 million Dark Energy Camera atop a telescope in Chile last year.
Image credit: Reidar Hahn/Fermilab
by Brian Vastag, The Washington Post

With the whir of a giant digital camera, the biggest mystery in the universe is about to become a bit less mysterious.

Fifteen years ago, the world of science was rocked by the discovery that, contrary to our notions of gravity, distant galaxies appeared to be flying apart at an ever-accelerating rate. The observation implied that space itself was stretching apart faster and faster. It was akin to watching a dropped ball reverse course, speed upward and disappear into the sky.

The discovery made many cosmologists - the scientists who probe the very nature of nature itself - acutely uncomfortable. For either our understanding of gravity is cockeyed, or some mysterious repulsive force - quickly and glibly dubbed "dark energy" - permeates the universe.

In 2011, the Nobel Committee blessed the improbable discovery as real, handing their prize in physics to the two teams that nearly simultaneously made the observation.

"As unhappy as it made some of us, the expansion of the universe is indeed accelerating," said Marc Kamionkowski, professor of physics and astronomy at Johns Hopkins University. "That's how the universe works."

Now, after years of planning and construction, four new projects at telescopes in Chile, Hawaii and the South Pole are getting a handle on what, exactly, is doing this unseemly pushing.

Leading the way is the world's most powerful digital camera, constructed at Fermilab, the Energy Department facility in Illinois. The $50 million Dark Energy Camera took a decade to plan and build, and it sports a resolution of 570 megapixels - about a hundredfold more pixels than a smartphone camera. Technicians installed it atop a telescope in Chile last year, and after initial jitters - the camera was so heavy it made the telescope jiggle - the camera has been "tested, tweaked and fine-tuned," said Joshua Frieman, the Fermilab scientist leading the project, which has enlisted 120 scientists from 23 countries.

On Aug. 31, the big camera began snapping its way across a huge swath of the southern sky.

Each click captures light from nearly 100,000 distant galaxies. Over the next five years, the project, called the Dark Energy Survey, will catalog some 300 million galaxies and thousands of exploding stars flung across distant space and time, in what Frieman called "the biggest galactic survey yet."

Every night, scientists will beam 400 gigabytes of camera data to a supercomputing center at the University of Illinois at Urbana-Champaign, where machines will build a giant time-lapse map of the universe going back some 8 billion years - or more than half way to the Big Bang that started it all.

Frieman calls it "a movie of cosmic history."

Scrutinizing this movie will narrow down the possibilities for what's causing cosmic acceleration. Because this acceleration can't be measured directly, its nature can only be divined indirectly, by measuring, for instance, how clumps of galaxies coalesce across space and time.

One possibility: Our understanding of gravity, explained by Einstein's general theory of relativity, breaks down across huge distances. The theory marked the culmination of Einstein's hardest thinking, and since its inception in 1916 it has withstood every test thrown at it. But general relativity may be incomplete.

Another possibility: A mysterious repulsive force permeates every point in the universe. This dark energy, if revealed, would be instant Nobel Prize fodder, Kamionkowski said.

"This is the one a lot of people would bet on," said David Spergel, an astrophysicist at Princeton University. "It's where I'd put most of my money."

Beyond these two possibilities, there are a "whole bunch of crazy ideas," Kamionkowski said. Spergel called most of these notions "intellectual aardvarks," saying, "They look beautiful only to their mothers." One such idea posits that the visible universe - what we think of as everything - is only one part of a far larger cosmos.

Combined with the Dark Energy Survey, three other projects coming online will further explore cosmic acceleration. Atop Mauna Kea in Hawaii, a camera at the Subaru Telescope is mapping galaxies in much of the northern sky. And at the South Pole and in Chile, two telescopes will take another tack, peering at the glow left over from the Big Bang. Studying this "cosmic background radiation" should reveal how cosmic acceleration has sped up or slowed down over the 13.7-billion-year history of the universe.

Combining data from all four projects could lead to a big "eureka moment," said Kamionkowski, a day the world's puzzled cosmologists would welcome.

"We don't know what makes up three quarters of the universe," Spergel said. "It's a little embarrassing."

Read more >>

Related Links:
KICP Members: Joshua A. Frieman
Scientific projects: Dark Energy Survey (DES)
 
Fermilab-University investigators receive $225,000 in collaborative seed grants
Fermilab, August 7, 2013
Fermilab-University investigators receive $225,000 in collaborative seed grants
Fermilab

Three teams of University and Fermi National Accelerator Laboratory researchers - one group that includes a researcher from Argonne National Laboratory - recently received $225,000, collectively, in Strategic Collaborative Initiative (SCI) seed grants from the University following a rigorous competition managed by Fermilab and the University. One of the teams received second-year funding. The FY 2013 recipients include:

- "An advanced, five orders of magnitude dynamic range, wafer-scale pixel system for X-ray science", University of Chicago Investigator: John Keith Moffat, Louis Block Professor of Biochemistry and Molecular Biology; Fermilab Investigator: Grzegorz Deptuch, Engineer IV, Particle Physics Division; Argonne Investigator: Robert Bradford, Assistant Physicist, X-ray Science Division.

- "Development of low noise electronics for the first direct Dark Matter search using CCDs" (funded for a second year), University of Chicago Investigator: Paolo Privitera, Professor of Astronomy and Astrophysics; Fermilab Investigators: Juan Estrada, Scientist II, Participles Physics Division and Gustavo Cancelo, Engineer IV, Scientific Computing Division.

- "SCENE: SCintillation Efficiency of Noble Elements", University of Chicago Investigator: Luca Grandi, Assistant Professor of Physics; Fermilab Investigator: Stephen Pordes, Scientist II, Particle Physics Division.

The Strategic Collaborative Initiatives Program began in 2006 when the University renewed its contract with the DOE to manage Argonne. The SCI program includes collaborative research projects, strategic joint appointments, and joint institutes. The University extended the program to Fermilab when it became co-manager of the lab in 2007.

Related Links:
KICP Members: Luca Grandi; Paolo Privitera
 
B-mode polarization spotted in cosmic microwave background
Physics World, July 25, 2013
The South Pole Telescope has seen B-mode polarization in the CMB.
The South Pole Telescope has seen B-mode polarization in the CMB.
by Jon Cartwright, Physics World

The South Pole Telescope (SPT) has made the first detection of a subtle twist in light from the cosmic microwave background (CMB), known as B-mode polarization. The signal, the existence of which has been long predicted, paves the way for a definitive test of inflation - a key theory in the Big Bang model of the universe.

"While this effect was fully expected, its detection is a milestone event in the use of the CMB to probe our universe," says Chuck Bennett, a leading expert in CMB observation based at Johns Hopkins University in Maryland, US, who was not involved with the study. "It is solid research and I believe the result."

Often called the afterglow of the Big Bang, the CMB is thought to have originated some 380,000 years into the life of the universe when neutral atoms first formed and space became transparent to light. Roughly speaking, it consists of microwaves with a temperature of about three kelvin, but it also contains details that have helped to refine our understanding of the early universe. The most noticeable of these details are variations in temperature of about 100 μK, which reveal density fluctuations in the early universe - the seeds of the stars and galaxies that we see today.

Polarized by scattering
The CMB does not only contain variations in temperature, however. Its radiation was scattered towards us from the universe's earliest atoms in the same way that blue light is scattered towards us from the atoms in the sky. And in the same way that the blue light from the sky is polarized - a fact you can check by wearing polarized sunglasses - so too is the light from the CMB polarized. Variations in CMB polarization were first detected in 2002 by the DASI interferometer in Antarctica and helped cosmologists understand the dynamics of the early universe.

These polarization variations were known as E-mode or gradient variations because they describe how the magnitude of polarization changes over the CMB. But there are even subtler variations known as B-mode variations, which describe the rotation or "curl" of CMB polarization. The majority of B-mode polarization is produced by galaxies acting as gravitational lenses, twisting the E-polarized light on its 14-billion-year journey from the other side of the observable universe. It is incredibly faint, producing temperature variations of about 0.4 μK and accounting for just one part in 10 million in the CMB temperature distribution. "B-mode polarization is very difficult to measure," says Duncan Hanson, a member of the SPT team who is based at McGill University in Canada.

The SPT has managed to detect B-mode polarization largely thanks to improvements in detector technology. Although the detection will probably have little application, it opens new doors in experimental cosmology. With more precision, B-mode signals could help cosmologists place tougher constraints on neutrino masses, which cannot be predicted in the Standard Model of particle physics.

Gargantuan ripples
But the biggest prize would be using B-mode signals to uncover evidence of primordial gravitational waves - gargantuan ripples in space-time. Such ripples are predicted to have been generated in inflation, a brief period prior to the formation of the CMB when the universe is thought to have undergone rapid expansion and given birth to large-scale structures.

Although most cosmologists today believe in inflation, the theory lacks crucial details such as how it started and stopped and there has been no way to test it. A detection of primordial gravitational waves would be strong evidence for the existence of inflation, which was first proposed back in 1980 by the American physicist Alan Guth.

"This possibility of detecting B modes from gravitational waves is a remarkable enough possibility that it is driving numerous experimental efforts," says cosmologist Arthur Kosowsky at the University of Pittsburgh in Pennsylvania, US. "SPT is the first to detect any B modes, [and now] several other experiments are in hot pursuit, so this is the first leg in what is shaping up to be an exciting race to the finish line over the next decade."

Others are looking
Gravitational-wave B modes could be detected by the European Space Agency's Planck observatory, which orbits the Earth, although the toughest competition will come from the BICEP telescope, which sits alongside the SPT, or the POLARBEAR or ACT telescopes in northern Chile. If the discovery is made by one of the ground-based telescopes it would continue the tradition of ground-based experimental cosmology firsts that began with the discovery of the CMB, made by the American astronomers Arno Penzias and Robert Wilson with the horn antenna at Bell Labs in Holmdel Township in New Jersey, US, in 1964.

"Results come out from space, and there's lots of press and beautiful results, and the ground-based work tends to get forgotten," says John Carlstrom, the principle investigator on the SPT team who is based at the University of Chicago in Illinois, US. "But the ground-based telescopes, balloons and short-duration flights are an extremely important part of the [experimental] program and have led the way consistently since the beginning. And they still do."

The discovery is described in the preprint arXiv:1307.5830.

Read more >>

Related Links:
KICP Members: John E. Carlstrom
Scientific projects: South Pole Telescope (SPT)
 
Polarization detected in Big Bang's echo
Nature, July 25, 2013
The South Pole Telescope has detected the first B-mode polarization signal in the cosmic microwave background.  <i>Daniel Luong-Van, NSF</i>
The South Pole Telescope has detected the first B-mode polarization signal in the cosmic microwave background.

Daniel Luong-Van, NSF
by Eugenie Samuel Reich, Nature

B-mode signal provides a way for astronomers to calculate neutrino masses.

Astronomers have detected a long-predicted polarization signal in the ripples of the Big Bang. The signal, known as B-mode polarization, is caused by the gravitational tug of matter on microwave photons left over from the Big Bang.

Its detection, posted this week to the arXiv preprint server and made by a microwave telescope at the South Pole, raises hopes that the signal can be used to map out the matter content of the Universe and determine the masses of the three types of neutrinos - in effect, using astronomy to achieve a key goal of particle physics. The detection also suggests that it might be possible to detect another type of B-mode, which would be evidence that the Universe, in the moment after the Big Bang, underwent a wrenching expansion known as inflation.

"The reason no one's been able to see this before is that it is a very small signal - about 1 part in 10 million," says Duncan Hanson, an astrophysicist at McGill University in Montreal, Canada, who led the work, which used ultrasensitive microwave receivers on the 10-metre South Pole Telescope (SPT). In comparison, the first measurements of ripples in the cosmic microwave background, released in 1992 by researchers using the NASA Cosmic Background Explorer satellite, was sensitive to differences of 4 parts in 100,000.

Other instruments are also seeking to detect B-modes, including the POLARBEAR experiment and the Atacama Cosmology Telescope (ACT), both in Chajnantor, Chile.

"They beat us, and hats off to them," says Lyman Page, an astronomer at Princeton University in New Jersey and principal investigator for the ACT. "It's intrinsically a neat signal and we all believe it will become an important tool for measuring the contents of the Universe."

David Spergel, a theoretical astrophysicist also at Princeton, agrees. "It's the first time polarization has been used to trace out large-scale structure in the Universe," he says.

The SPT was switched on in 2007 and has used the cosmic microwave background to map out the positions of galaxies and star clusters. Its sensitive microwave receivers were installed in 2012 and were able to detect variations in the B-mode signal across very small scales on the sky, says John Carlstrom, an astrophysicist at the University of Chicago in Illinois and principal investigator of the SPT. To use the signal to pin down the masses of neutrinos, which make up an unknown proportion of the matter being mapped, astronomers will have to survey a patch of sky much larger than the 100 square degrees mapped by the SPT. Still, Carlstrom says it is not implausible that telescopes will determine the neutrino mass in the next few years, before planned particle-physics experiments attempt to do the same thing with beams of neutrinos on Earth.

Yet the ultimate goal of the microwave-polarization experiments is not to do particle physics but cosmology. They are chasing a different class of 'primordial' B-modes, which are thought to have been generated by the fast expansion of space during inflation. Any detection would be a definitive confirmation of inflation - one of the core theories of cosmology - and would fix its energy scale, which would be useful to physicists working to develop theories of quantum gravity. But primordial B-modes would exist as tiny variations on large scales of more than 1 degree across - too large for the SPT to find statistical significance with the relatively small patch of sky it surveyed. The European Space Agency's Planck satellite, which surveys the whole sky, might be able to make them out. It is also possible that they will be discernible in smaller data sets such as the SPT's once the gravitational B-modes have been mapped and removed, to potentially reveal any primordial signal beneath. The latest observation from the SPT suggests that this approach to detecting B-modes is a good prospect, says Spergel. "It's a good sign that they've measured this from the ground."

Read more >>

Related Links:
KICP Members: John E. Carlstrom
Scientific projects: South Pole Telescope (SPT)
 
Angela Olinto's cosmic needle in a haystack
American Association for the Advancement of Science, June 13, 2013
AAAS Fellow Angela Olinto's specialty is the study of ultra-high-energy cosmic rays. Their exact origin is one of their intriguing mysteries.   <i>Photo: Delia O'Hara</i>
AAAS Fellow Angela Olinto's specialty is the study of ultra-high-energy cosmic rays. Their exact origin is one of their intriguing mysteries.

Photo: Delia O'Hara
by Delia O'Hara, American Association for the Advancement of Science

When Angela Olinto was 20 years old, and the top student at the Pontificia Universidade Catolica in Rio de Janeiro in her native Brazil, she came down with a serious inflammatory disease called polymyositis, which weakens the skeletal muscles, and can be fatal.

How did Olinto spend what she thought could be her last year on Earth? She launched a full-bore effort to get into the physics graduate program at the Massachusetts Institute of Technology.

Consider that a glimpse into the character of Olinto, who chairs the Department of Astronomy and Astrophysics at the University of Chicago, and was named an AAAS Fellow in 2012.

Olinto has had one recurrence of polymyositis since college, and still lives with its threat. "I got a bit lucky," she says. "I am very impressed when I think about it, though. What was I thinking? If you think you only have a year left to live, are you going to spend it writing essays, doing exams and applying to graduate school, or are you going to go sit on a beach somewhere?"

That ability to focus on the task at hand, no matter what else is going on, serves Olinto well in her specialty, the study of ultra-high-energy cosmic rays, which is a little like looking for a needle in a haystack - if the haystack were as big as all outdoors. These tiny space invaders, nuclei packing energy greater than 10^18 electron volts (eV), come from outside our galaxy, from hundreds of millions or billions of light years away.

Their exact origin is one of the intriguing mysteries about ultra-high-energy cosmic rays. Supernova explosions of dying stars in our own galaxy are thought to produce less energetic cosmic rays, but "we know supernovae are not the accelerator" for ultra-high-energy particles, Olinto says. She is part of a U. of C. team that has shown that "baby" pulsars could be the source of ultra-high-energy cosmic rays, but only during the first year of their lives.

Even though cosmic rays break up in the Earth's atmosphere, the "daughter" (or secondary) particles are still powerful enough to pass through our bodies. Their power to change genetic material may have played a role in evolution.

Why should we care about something we can't see or feel? For one thing, if we ever want to travel beyond our planet, we will have to know how to protect ourselves against cosmic rays. In outer space, over time, their radiation can cause serious damage to human beings, Olinto says.

The real potential of cosmic rays for science, though, lies in having a chance to study super-energetic ones like the so-called "oh my God particle," the most powerful cosmic ray ever observed, in Utah in 1991, which registered energy of 3.2 x 10^20 eV, tens of millions of times more powerful than anything scientists can now create in a man-made accelerator.

"Nobody expected particles that energetic to exist," Olinto says. Discovering particles with even higher energies could yield exponential advances in scientists' understanding of how the universe works, she says.

"The greater the energy, the more interesting the physics becomes. We don't know if nature can actually reach [even higher] energies [with] an accelerator. We do know 'the Big Bang' had that energy. These are questions we can only answer if we have huge volumes [of cosmic rays] to look at."

Cosmic rays at energy levels of 10^19 eV hit the Earth at a rate of only about one per square kilometer per year. For particles with energy above 10^20 eV, it's more like one per square kilometer per century. "The higher the energy, the rarer they are," Olinto says.

So the greater the area an observatory covers, the better the chance of "capturing" a really interesting particle. In the past, large collectors have been deployed over vast territories to catch "secondary" particles that rain down on Earth, each bearing a portion of the original energy from "primary" cosmic rays that have broken up in our atmosphere.

Olinto has played a key role in the evolution of cosmic ray detectors. She is part of the international collaboration of nearly 500 scientists from 18 countries at the Pierre Auger Observatory in western Argentina.

The Auger Observatory is a hybrid system of 1,600 huge water tanks spread out over an area the size of Rhode Island, and optical fluorescence detectors, which together document the activity of high-energy particles and the "air showers" that fall out from them.

Olinto led the design of Auger North, a similar but much larger collector that was planned in Colorado, but that project fell to funding cuts during the recent recession - a tremendous disappointment, she says now.

Olinto didn't sit around moping about the loss of Auger North, though, notes Michael Turner, a professor at the University of Chicago and director of the Kavli Institute for Cosmological Physics there. Instead, "she put together plans for the largest cosmic-ray detector ever," Turner says.

Olinto is part of a group working to put an "extreme universe space observatory" on the Japanese Experiment Module, which is already on the International Space Station.

The new telescope, JEM-EUSO, will point not toward space, but toward the Earth, monitoring the atmosphere from above. "The atmosphere is really the detector," Olinto says. Lasers fired from the ground will see what the telescope is seeing as the ISS passes overhead.

As the "principal investigator" for the U.S. team in the collaboration, and a theorist herself, Olinto must engage experimental scientists in defining goals, and "get this guy off the ground" by 2017. "The bigger the telescope, the more events you can see," she says, but bigger is also more expensive - so goal-setting will be a key part of the effort.

For Olinto, the 'wow' part of her job is the fact that actual matter is coming from another galaxy, but the possibility that these extremely energetic cosmic rays might also be carrying new understandings for scientists about how the universe works intrigues her, too.

"Scientists are very curious," she says. "We might be curious about something that looks completely irrelevant, and it turns out to be a really amazing thing. Or it could be irrelevant. We don't know. If we knew, we wouldn't be looking at it."

Read more >>

Related Links:
KICP Members: Angela V. Olinto; Michael S. Turner
 
Clarence Chang to receive DOE's Early Career Research Program Funding
DOE's Office of Science, May 8, 2013
Clarence Chang to receive DOE's Early Career Research Program Funding
DOE's Office of Science

WASHINGTON, DC - DOE's Office of Science today announced that 61 scientists from across the nation will receive up to $15.3 million in funding for research as part of DOE's Early Career Research Program. The effort, now in its fourth year, is designed to bolster the nation's scientific workforce by providing support to exceptional researchers during the crucial early career years, when many scientists do their most formative work.

"By providing support to the most creative and productive researchers in their early career years, this program is helping to build and sustain America's science workforce," said Patricia M. Dehmer, Acting Director of DOE's Office of Science. "We congratulate this year's winners on having competed successfully for these very selective awards, and we look forward to following their accomplishments over the next five years."

Read more >>

Related Links:
KICP Members: Clarence L. Chang
Scientific projects: South Pole Telescope (SPT)
 
New dark matter detector begins search for invisible particles
The University of Chicago News Office, May 7, 2013
The COUPP-60 detector installed at the SNOLAB underground laboratory in Ontario, Canada.
The COUPP-60 detector installed at the SNOLAB underground laboratory in Ontario, Canada.
by Steve Koppes, The University of Chicago News Office

Scientists heard their first pops last week in an experiment that searches for signs of dark matter in the form of tiny bubbles.

They will need to analyze them further in order to discern whether dark matter caused any of the COUPP-60 experiment's first bubbles at the SNOLAB underground science laboratory in Ontario, Canada. Dark matter accounts for nearly 90 percent of all matter in the universe, yet it is invisible to telescopes.

"Our goal is to make the most sensitive detector to see signals of particles that we don't understand," said Hugh Lippincott, a postdoctoral scientist with Fermi National Accelerator Laboratory. Lippincott has spent much of the past several months leading the installation of the one-of-a-kind detector at SNOLAB, 1.5 miles underground.

COUPP, or the Chicagoland Observatory for Underground Particle Physics, is a dark-matter experiment funded by the Department of Energy's Office of Science. Fermilab managed the assembly and installation of the experiment's detector. Leading the experiment is Juan Collar of the Kavli Institute for Cosmological Physics at the University of Chicago.

"Operation of COUPP-60 at SNOLAB is the culmination of a decade of work at the University of Chicago and Fermilab," said Collar, an associate professor in physics. "This device has the potential to become the most sensitive dark matter detector in the world, for both modes of interaction expected from Weakly Interacting Massive Particles."

The COUPP-60 detector is a jar filled with 60 kilograms of purified water and CF3I - an ingredient found in fire extinguishers. The liquid in the detector is kept at a temperature and pressure slightly above the boiling point, but it requires an extra bit of energy to actually form a bubble. When a passing particle enters the detector and disturbs an atom in the clear liquid, it provides that energy.

Dark matter particles, which scientists think rarely interact with other matter, should form individual bubbles in the COUPP-60 tank.

"The events are so rare, we're looking for a couple of events per year," Lippincott said.

Other, more common and interactive particles such as neutrons are more likely to leave a trail of multiple bubbles as they pass through.

Over the next few months, scientists will analyze the bubbles that form in their detector to test how well COUPP-60 is working and to determine whether they see signs of dark matter. One of the advantages of the detector is that it can be filled with a different liquid, if scientists decide they would like to alter their techniques.

"We are already working on a 500-kilogram chamber, to be installed in the same site starting in 2015," Collar said.

The COUPP-60 detector is the latest addition to a suite of dark-matter experiments running at SNOLAB. Scientists run dark matter experiments underground to shield them from a distracting background of other particles that constantly shower Earth from space. Dark matter particles can move through the mile and a half of rock under which the laboratory is buried, whereas most other particles cannot.

Scientists further shield the COUPP-60 detector from neutrons and other particles by submersing it in 7,000 gallons of water.

Scientists first proposed the existence of dark matter in the 1930s, when they discovered that visible matter could not account for the rotational velocities of galaxies. Other evidence, such as gravitational lensing that distorts the view of faraway stars and the inability to explain how other galaxies hold together if not for the mass of dark matter, have improved scientists' case. Astrophysicists think dark matter accounts for about a quarter of the matter and energy in the universe. But no one has conclusively observed dark matter particles.

The COUPP experiment includes scientists, technicians and students from UChicago, Indiana University South Bend, Northwestern University, University of Valencia, Virginia Tech, Fermilab, Pacific Northwest National Laboratory and SNOLAB.

- This article was adapted from a Fermilab announcement:
http://www.fnal.gov/pub/presspass/press_releases/2013/Dark-Matter-Detector-2013.html

Read more >>

Related Links:
KICP Members: Juan I. Collar
Scientific projects: Chicagoland Observatory for Underground Particle Physics (COUPP)
 
Michael S. Turner, The Nora and Edward Ryerson Lecture: Quarks and the Cosmos
The University of Chicago News Office, May 2, 2013
Michael S. Turner, The Nora and Edward Ryerson Lecture: Quarks and the Cosmos
The University of Chicago News Office

Pioneering University of Chicago cosmologist Michael S. Turner focuses his remarks on "the Chicago School of Cosmology," from Edwin Hubble and George Ellery Hale to the present. Hubble, SB 1910, PhD 1917, discovered that the universe consists of billions of galaxies and that it has been expanding since it began in a big bang. Hale was the first chairman of the University's Department of Astronomy and Astrophysics. He also founded Yerkes Observatory, which under his leadership developed the big reflecting telescopes that are the workhorses of optical astronomy today, making discoveries from the expanding universe to planets orbiting other stars. Turning to more recent times, Turner discusses efforts that started in the 1980s at UChicago to establish the new field of particle astrophysics and cosmology. At that time, the Chicago School, consisting primarily of the late David Schramm, Edward "Rocky" Kolb, the Arthur Holly Compton Distinguished Service Professor in Astronomy and Astrophysics, and Turner, was alone in pushing this idea. "Today this idea that there are deep connections between the very big and the very small is universally accepted, has propelled the field to its current prominence, and underpins our understanding of the universe," Turner said. "As we say at Chicago, ideas matter!" The Ryerson Lecture grew out of a 1972 bequest to the University by Nora and Edward L. Ryerson, a former chairman of the board of trustees. The lecture honors excellence in academic pursuits. A faculty committee selects the Ryerson Lecturer based on research contributions of lasting significance.

Read more >>

Related Links:
KICP Members: Michael S. Turner
 
Alumni Award winners include Nobelist James Cronin
The University of Chicago News Office, April 18, 2013
Nobel laureate James Cronin, SM'53, PhD'55, will receive the Alumni Medal during the annual Alumni Awards ceremony June 8 in Rockefeller Memorial Chapel.
Nobel laureate James Cronin, SM'53, PhD'55, will receive the Alumni Medal during the annual Alumni Awards ceremony June 8 in Rockefeller Memorial Chapel.
The University of Chicago News Office

Nobel laureate James Cronin, SM'53, PhD'55, will receive the Alumni Medal, the highest honor for a UChicago alumnus, while 13 others will be recognized for their career accomplishments during Alumni Weekend.

Cronin shared the Nobel Prize in physics in 1980 for showing that the laws of nature operate differently on matter and antimatter - a discovery that opened an entirely new research direction for particle physics. More recently, Cronin led the effort to build the Pierre Auger Observatory in Argentina. The Auger collaboration has become the most successful cosmic ray observatory and has inspired more than 400 scientists in 17 countries to explore this frontier of knowledge. A professor emeritus in Astronomy and Astrophysics, Physics, and the College, Cronin is also a dedicated professor, winning the Quantrell Award for Undergraduate Teaching in 1994.

The Alumni Medal recognizes achievement of an exceptional nature in any field, vocational or voluntary, covering an entire career. In addition to the Alumni Medal, the University will recognize distinguished alumni and faculty members who have made exceptional contributions to UChicago, to their professions, and to their communities, across six different categories.

This year's 14 Alumni Award recipients include a global economist governing the Banco de Mexico, one of the developers of video game franchise Halo, a renowned statistician in both the sports and political fronts, and a philanthropist working to create a tuberculosis-free world.

The University of Chicago Alumni Association and the Alumni Board of Governors will hold the 72nd annual Alumni Awards Ceremony at 11 a.m. on Saturday, June 8 in Rockefeller Memorial Chapel. The ceremony is free and open to the public.

Read more >>

Related Links:
KICP Members: James W. Cronin
Scientific projects: Pierre Auger Observatory (AUGER)