Space Warps Collaboration

The green crosshairs pinpoint a gravitational lens lurking in an astronomical image.

Think you can find space warps? Astronomers have recruited thousands of citizen scientists to look for exoplanets, galaxies, moon craters and other cosmic curiosities — and now they need your help to go after one of the weirdest phenomena in space-time: gravitational lenses.

The Space Warps website gives Internet users the opportunity to sift through telescope images and spot galaxies so massive they bend the light rays that pass near them, like a lens. The venture could help crack some of the secrets of dark matter, the mysterious cosmic stuff that is more plentiful than the ordinary matter we see around us.

"Not only do space warps act like lenses, magnifying the distant galaxies behind them, but we can also use the light they distort to weigh them, helping us to figure out how much dark matter they contain and how it’s distributed," Oxford University physicist Phil Marshall, one of the leaders of the Space Warps research team, said in Wednesday's kickoff announcement.  "Gravitational lenses help us to answer all kinds of questions about galaxies, including how many very low-mass stars such as brown dwarfs — which aren’t bright enough to detect directly in many observations — are lurking in distant galaxies."

Space Warps is the latest gem in Zooniverse's constellation of online citizen-science ventures — a constellation that also includes Planet Hunters, Galaxy Zoo, Moon Zoo and much, much more. The warp-hunting effort follows the model set by those other projects: Participants are given online training exercises to sharpen their lens-spotting skills, and then they're set loose to check sky survey images from the Canada-France-Hawaii Telescope.

"Computer algorithms have already scanned the images from the CFHT survey, but there are likely to be many more space warps that the algorithms have missed. Realistic simulated space warps are dropped into some images to train the volunteers how to spot them, and reassure people that they are on the right track,’ said Anupreeta More, project co-leader from Kavli IPMU in Tokyo.

Galaxy Zoo already has demonstrated that human eyes and brains are much better than automated computer software when it comes to recognizing the subtle characteristics of astronomical phenomena. Dozens of scientific papers have been spun off from Galaxy Zoo searches — including reports on the headline-grabbing blob of green gas known as "Hanny's Voorwerp."

Space Warps could well uncover similar curiosities. Warp-hunters will be able to discuss their finds with each other and with experts on the project's online forum, and even create computer models of their discoveries. A list of gravitational lenses will be published for amateurs and professionals to investigate further.  

"Even if individual visitors only spend a few minutes glancing over 40 or so images each, that's really helpful to our research — we only need a handful of people to spot something in an image for us to say that it's worth investigating," said Oxford's Aprajita Verma, another leader of the Space Warps team.

So what are you waiting for?

More about gravitational lenses:

• Cosmic lenses find farthest galaxy yet
• Crazy cosmic lens focuses on dark matter
• Dark energy illuminated by cosmic lens

The Space Warps collaboration currently includes Phil Marshall, Aprajita Verma, Matthias Tecza, Chris Lintott, Rob Simpson (University of Oxford), Anupreeta More, Surhud More (Kavli IPMU), Amit Kapadia, Kelly Borden, David Miller, Arfon Smith (Adler Planetarium), Jean-Paul Kneib (EPFL Lausanne), Rafael Kueng, Prasenjit Saha (University of Zurich), and citizen scientists Elisabeth Baeten, Claude Cornen, Cecile Faure, Thomas Jennings, Stuart Lowe, Christine Macmillan, Julianne Wilcox and Layne Wright. Organizers say it is about to get a lot bigger.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the NBC News Science Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA file

A fish-eye view of the International Space Station from July 2011 shows the $2 billion Alpha Magnetic Spectrometer (AMS) in the foreground. A Russian Progress cargo ship and a Soyuz crew capsule are docked on the left end of the station. The structure extending to the left of the AMS is a thermal radiator. Off to the right, the shuttle Atlantis is docked to the station's Tranquility module.

Scientists say a $2 billion antimatter-hunting experiment on the International Space Station has detected its first hints of dark matter, the mysterious stuff that makes up almost a quarter of the universe.

The evidence from the Alpha Magnetic Spectrometer, revealed Wednesday at Europe's CERN particle physics lab, is based on an excess in the cosmic production of anti-electrons, also known as positrons. The AMS research team can't yet rule out other explanations for the excess, but the fresh findings provide the best clues yet as to the nature of dark matter.

"Over the coming months, AMS will be able to tell us conclusively whether these positrons are a signal for dark matter, or whether they have some other origin," Samuel Ting, an astrophysicist at the Massachusetts Institute of Technology who leads the international AMS collaboration, said in a CERN news release.

The results have been published in Physical Review Letters and were discussed during a NASA news conference.

Dark matter is so named because it hasn't been detected directly through electromagnetic emissions, but primarily through its gravitational effect. Precise measurements of the movements of galaxies and galaxy clusters, as well as studies of the big bang's afterglow, indicate that it accounts for 22.7 percent of the universe's content. Another mysterious factor known as dark energy makes up 72.8 percent, leaving just 4.5 percent for ordinary matter.

Scientists have theorized that ultra-high-energy collisions involving dark matter particles could produce more positrons than expected. The best places to detect such collisions are in huge underground experiments such as CERN's Large Hadron Collider — or in outer space, where cosmic rays can be measured more easily than they are on Earth. 

The Alpha Magnetic Spectrometer is the most sensitive cosmic-ray detector ever put into orbit. Researchers from 16 countries worked for well more than a decade to get AMS ready for the space station, but it literally took an act of Congress to get the extra money needed for the launch. The bus-sized device was brought up on the shuttle Endeavour and installed in 2011, during the shuttle fleet's second-last mission. 

Since then, readings from the AMS have been flowing in to Ting and his colleagues for analysis. CERN said the results announced on Wednesday are based on 25 billion recorded events, including 400,000 positrons with energies between 500 million electron volts and 350 billion electron volts. "This represents the largest collection of antimatter particles recorded in space," CERN said.

Researchers noticed an increase in the fraction of positrons detected in the range of 10 billion to 250 billion electron volts. They said the data showed no significant variation over time, or any preferred incoming direction. All this is consistent with the annihilation of dark matter particles in space.

CERN

This chart compares the results from AMS on positron emissions with results from other experiments. AMS measurements at different energy levels are represented by the red dots with error bars.

Other experiments have recorded similar increases in positron production, but AMS was able to chart the rise in unprecedented detail. Ting compared the resolution to seeing something with the naked eye vs. an electron microscope. "It is these fine features that are the difference between us and the rest of the experiments," he told reporters.

Further evidence is needed, however: It's possible that the bump in positrons could be created by emissions from pulsars spread across the galactic plane. The most promising hypothesis suggests that dark matter is part of a yet-to-be-detected array of "supersymmetric" particles, and if that concept is correct, researchers should see a sharp drop in the positron emissions at energies higher than 250 billion electron volts.

Ting said there's not yet enough data to render a decision about such a drop-off. "We want to know how quickly it drops off, how sharp is the drop-off," he told NBC News. "It's the way it drops off that tells you whether it's dark matter collisions, or from pulsars." 

He pointed out that the newly released findings are based on just 10 percent of the data AMS is expected to collect.

"When you take a new precision instrument into a new regime, you tend to see many new results, and we hope this this will be the first of many," Ting said. "AMS is the first experiment to measure to 1 percent accuracy in space. It is this level of precision that will allow us to tell whether our current positron observation has a dark matter or pulsar origin."

Future revelations are expected to come from AMS as well as from the Large Hadron Collider and other underground laboratories.

"The AMS result is a great example of the complementarity of experiments on Earth and in space,” CERN Director General Rolf Heuer said in Wednesday's statement. “Working in tandem, I think we can be confident of a resolution to the dark matter enigma sometime in the next few years."

Update for 4:40 p.m. ET April 3: One of the experiments that could make a direct detection of dark matter particles in the months ahead is the Large Underground Xenon Experiment. LUX is located in an old gold mine, almost a mile deep in the Black Hills of South Dakota. The project's scientists will keep watch for telltale interactions between dark matter and the xenon in their detector. In an emailed statement, LUX co-spokesperson Richard Gaitskell, a physicist at Brown University, hailed the AMS results but said that questions remain:

"Obviously it’s a fantastic new instrument. It’s considerably more sensitive than anything we’ve previously flown as far as looking for antiparticles. So it’s a tremendous step forward.

"The results themselves are consistent with a flux of antiparticles that come from dark matter. On the downside, no aspect of the data that’s been discussed so far allows one to differentiate between an explanation that these antiparticles are coming from dark matter or from another astrophysical source.

"What we see is that at the higher-energy regime that the detector, there is a significant increase in the positron flux. That’s interesting, but it’s been recorded by previous instruments. What we were hoping to see was some additional structure. We’d like to see a bump that has some upper energy threshold or edge, rather just a rise at higher energies. Right now, the new data from AMS does not provide a definitive indication of an upper edge. We’d like to see something like that as direct evidence of dark matter."

NASA Administrator Charles Bolden issued a statement that focusing on the roles played by the space agency and the International Space Station. " I am confident that this is only the first of many scientific discoveries enabled by the station that will change our understanding of the universe," Bolden said. "Multiple NASA human spaceflight centers around the country played important roles in this work, and we look forward to many more exciting results from AMS."

More about dark matter:

• How to catch a dark matter particle
• Dark matter finding thrown into question
• Why dark matter matters

To watch the full NASA news conference, click to the 48-minute mark in this Ustream recording.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

ESA

This all-sky map from the Planck probe charts the imprint of the big bang's cosmic afterglow.

The Planck cosmology probe has forced scientists to revise their estimates of the universe's age and the cosmic balance of matter and dark energy — and now it's led a physicist to remix the sound of the big bang as well.

The new big-bang sound was created over the weekend by John Cramer, a professor emeritus of physics at the University of Washington. The audio file follows up on Cramer's decade-old audio rendition of the big bang, which was based on data from NASA's Wilkinson Microwave Anisotropy Probe, or WMAP.

Planck and WMAP both charted subtle variations in the all-sky cosmic microwave background, a super-faint glow of stretched-out radiation from a time when the universe was 380,000 years old. The variations amount to mere millionths of a degree in temperature, but they record the imprint of fluctuations left behind by the big bang.

Cramer released his original WMAP big-bang sound 10 years ago, but the Planck readings were so much better that a remix was in order.

"The new frequency spectrum goes to much higher frequencies than did the WMAP analysis, and therefore offers a more 'high-fidelity' rendition of the Sound of the Big Bang," Cramer explained on a Web page providing the updated sound files. We're featuring the 20-second version, but you can download versions that play out for as long as 500 seconds.

"I recommend the 100-second version, but you can choose for yourself," Cramer said.

The sound follows the curves in Planck data to reflect the propagation of pressure waves through the medium of the early universe during the first 760,000 years of its evolution. The time scale has been speeded up astronomically, of course, and Cramer figures that the frequency has been scaled up by a factor of 100 septillion (that's a 1 followed by 26 zeroes).

"The actual Big Bang frequencies, which had wavelengths on the order of a fraction of the size of the universe, were far too low to be heard by humans (even had any been around)," Cramer explained.

Ten years ago, Cramer said that when he played the sound of the WMAP data on his computer, his dogs pricked up their ears and listened attentively. "There was less reaction from the dogs this time, but there was some barking when the big bang sound initially came on," Cramer told NBC News in an email.

Sharp-eared listeners with a good sound system will notice that the Planck remix doesn't rattle the speakers as much as the WMAP original does. "The big bang sound is different because of the higher frequency components from Planck, and because I decided to shift the frequency scale factor to make less bass (since not everyone has a sub-woofer on their PC)," Cramer said.

In addition to the big-bang sound, Cramer has several unorthodox claims to scientific fame, including his long-running column for Analog magazine; his science-fiction novels, "Twistor" and "Einstein's Bridge"; and his experiment to find out whether quantum mechanics would allow for backward causality.

Cramer said his retrocausality experiment is currently in limbo. He has always said that there might be some subtle quantum effect that would rule out backward causality, and so far that's been the case.

"The Mark II version of the retrocausality experiment has concluded for now, defeated by detector noise," he said in his email. "I'm currently in the process of writing a new pre-proposal (to a government organization I won't name) seeking funding for a Mark III version of the experiment.  It would use noise-free superconducting-transition single photon detectors instead of the too-noisy avalanche photodiodes, would be down-scaled in wavelength a bit so that the entangled photon pairs would be at wavelengths matching the communication industry standard wavelengths for fiber optics, and would use two switched single-mode fiber optic Mach-Zehnder interferometers instead of lenses, prisms and mirrors on an optics table.  Said organization is interested because there is the possibility of zero-time-delay communication with distant space missions."

Read that last sentence again: Someone in the government is interested in zero-time-delay communication with distant space missions. Albert Einstein's theories suggest that information can't be transmitted any faster than the speed of light, but Einstein himself said quantum mechanics might open the door for "spooky action at a distance." Zero-time-delay communication certainly sounds spooky — but is it possible? Stay tuned.

Scott Eklund / Seattle P-I file

University of Washington physicist John Cramer, seen here in a 2007 photo, has been working on a laser experiment to test whether causality can work backward in time.

More weird physics:

• Math twisted for faster-than-light travel
• Bizarre quantum physics may play role in life
• New view: Big bang was a big crystallization

Audio clips: Copyright 2013 John G. Cramer.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

ESA

The Planck mission has produced the most detailed all-sky map of the cosmic microwave background radiation.

The European-led team behind the Planck cosmology probe on Thursday released the mission's first all-sky map of the cosmic microwave background — a post-big-bang "baby picture" that suggests our universe is about 100 million years older than scientists thought.

The map traces subtle fluctuations in temperature that were imprinted on the deep sky when the cosmos was just 370,000 years old. Scientists say the imprint reflects ripples that arose as early as the first nonillionth of a second of the universe's existence. These ripples are thought to have given rise to today's vast cosmic web of galaxy clusters and dark matter.

"To a cosmologist, this map is a gold mine of information," University of Cambridge astrophysicist George Efstathiou, a member of the Planck science team, said during a European Space Agency news conference in Paris. He joked that not long ago, cosmologists might have "given up their children" to have such a map in their hands.

The $900 million (€700 million) Planck probe was launched on a European Ariane 5 rocket in 2009, along with the infrared-sensitive Herschel space telescope. Planck produced its first all-sky radiation map in 2010. Since then, scientists have fine-tuned the image to remove the bright emissions from the Milky Way and other foreground sources, leaving only the background radiation.

Two NASA satellites — the Cosmic Background Explorer and the Wilkinson Microwave Anisotropy Probe, also known as COBE and WMAP — produced earlier versions of the baby picture. Those findings determined that the universe is made up of 4.5 percent ordinary matter, 22.7 percent dark matter, and 72.8 percent dark energy. The results also showed that the universe is geometrically "flat" to a margin of error of 0.4 percent, and helped scientists estimate the universe's age at 13.7 billion years.

NASA

Planck's map of the cosmic microwave background has significantly higher resolution than the readings that were made during previous missions such as COBE and WMAP, as shown in this graphic.

Planck can produce cosmological maps with three times the resolution of WMAP, and at least 10 times the temperature sensitivity. As a result, the estimates of the universe's age and composition have undergone some additional fine tuning. Planck's readings indicate that the universe's expansion rate is slower than previously thought — which means the universe is older.

Planck's estimate for the age of the universe is 13.82 billion years.

Martin White, a member of the Planck team from the University of California at Berkeley, told NBC News that Planck's estimate narrowed down the error bars on previous estimates. "In that sense, it's very consistent, but much more precise," he said.

The Planck team's breakdown of the universe's constituents is 4.9 percent ordinary matter, 26.8 percent dark matter and 68.3 percent dark energy, he said. "There's less stuff that we don't understand, by a tiny amount," Efstathiou said. As a result of the shift toward more matter and less dark energy, "an awful lot of people are going to be revising their calculations," White said.

Efstathiou said the Planck data also pointed to some "strange features" in the cosmic microwave background that may point to new frontiers in physics, including an unexplained dip at one point of the power spectrum, and an unusual distribution of large-scale fluctuations that roughly followed the plane of the solar system.

"Why characteristics of the CMB should relate to our solar system is not understood. ... I was explicitly told not to say anything about God in this talk — which I've just violated," Efstathiou said half-jokingly.

ESA

This graphic highlights anomalies seen in the Planck data. One anomaly is an asymmetry in the average temperatures on opposite hemispheres of the sky (indicated by the curved line), with slightly higher average temperatures in the southern ecliptic hemisphere and slightly lower average temperatures in the northern ecliptic hemisphere. This runs counter to the mainstream view that the universe should be broadly similar in any direction we look. There is also a cold spot that extends over a patch of sky that is much larger than expected (circled). The anomalous regions have been enhanced here to make them more clearly visible.

Planck's data set should help scientists do a reality check on many of the hypotheses proposed by cosmologists, including the view that the universe underwent rapid and far-reaching inflation in the first moments of its existence, as well as the claim that there are six or seven spatial dimensions in addition to the three we perceive.

An initial reading of the data appears to favor the simple models for the inflationary big bang, and rule out a lot of the complex models. "We think that they will be facing a dead end," said Krzysztof Gorski, a member of the Planck team from NASA's Jet Propulsion Laboratory.

ESA Director General Jean-Jacques Dordain noted that so far, the mission has delivered just half of the data it's expected to produce. The rest of the data is scheduled to come out in 2014 and 2015. "Today is not the end of the story," he told reporters. Efstathiou put it another way, paraphrasing one of Arnold Schwarzenegger's best-known catchphrases: "We'll be back."

More about cosmology:

• WMAP scientists unveil their best 'baby picture'
• Japanese string theorists simulate big bang
• Scrunched-up dimensions untangled

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

This story was originally published on Thu Mar 21, 2013 5:49 AM EDT

Corbis

An artist's conception visualizes the big bang at the universe's beginning — or could it be the end?

BOSTON — If the "Higgs-like particle" discovered last year is really the long-sought Higgs boson, the bad news is that its mass suggests the universe will end in a fast-spreading bubble of doom. The good news? It'll probably be tens of billions of years before that particular doomsday arrives.

That's one of the weirder twists coming out of the continuing analysis of results from Europe's Large Hadron Collider, which produced the first solid evidence for the existence of the Higgs boson last year. Current theory holds that the Higgs boson plays a role in imparting mass to other fundamental particles. Confirming the discovery of the Higgs would fill in the last blank spot in that theory, known as the Standard Model.

Physicists discussed the state of the Higgs quest in Boston on Monday during the annual meeting of the American Association for the Advancement of Science.

So far, the particle that was found at the LHC fits all the requirements for the Higgs boson, but scientists aren't quite ready to confirm that the particle is really, truly the Higgs boson. It could be, say, just the first of multiple particles involved in the process. "The door is still very much open that there's [another] particle that has a role to play, or even more than that," said Christopher Hill, a physicist at Ohio State University who is also deputy physics coordinator for the LHC's Compact Muon Solenoid experiment.

The LHC has just started a two-year shutdown for equipment upgrades — and Howard Gordon, deputy chair of the physics program at Brookhaven National Laboratory, said "it's going to take another few years" after the collider is restarted to confirm definitively that the newfound particle is the Higgs boson.

In the meantime, physicists have tightened their estimates of the particle's mass: Hill said the current estimate from the Compact Muon Solenoid is 125.8 billion electron volts, or 125.8 GeV, plus or minus 0.6 GeV. The figure from the LHC's other Higgs-boson detector, known as ATLAS, is 125.2 GeV, plus or minus 0.7 GeV.

Those figures can be factored into equations that point to the long-term fate of the universe, said Joseph Lykken, a theoretical physicist at Fermilab.

So what's the outlook?

"If you use all the physics that we know now, and we do what we think is a straightforward calculation, it's bad news," Lykken said. "It may be that the universe we live in is inherently unstable. At some point, billions of years from now, it's all going to be wiped out."

He said the parameters for our universe, including the Higgs mass value as well as the mass of another subatomic particle known as the top quark, suggest that we're just at the edge of stability, in a "metastable" state. Physicists have been contemplating such a possibility for more than 30 years. Back in 1982, physicists Michael Turner and Frank Wilczek wrote in Nature that "without warning, a bubble of true vacuum could nucleate somewhere in the universe and move outwards at the speed of light, and before we realized what swept by us our protons would decay away."

Lykken put it slightly differently: "The universe wants to be in a different state, so eventually to realize that, a little bubble of what you might think of as an alternate universe will appear somewhere, and it will spread out and destroy us."

That alternate universe would be "much more boring," Lykken said. Which led him to ask a philosophical question: "Why do we live in a universe that's just on the edge of stability?" He wondered whether a universe has to be near the danger zone to produce galaxies, stars, planets ... and life.

Even Hill found it interesting that the parameters of particle physics put our universe right along the critical line. "That's something new, which we didn't know before, and which leads some of us to that there's something else coming," Hill said.

When Hill referred to "something else," he was talking about new discoveries in physics — not the end of the world. Lykken emphasized that it would be at least tens of billions of years before vacuum instability took hold.

"To get the exact number, we need more funding," he joked.

More about the fate of the universe:

• A bleak and lonely outlook for the universe
• Will time end in 3.7 billion years? Maybe, or maybe not
• Flash interactive: Beyond the big bang

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Alan Boyle / msnbc.com

British physicist Stephen Hawking jokes about the future discoveries that could earn him a Nobel Prize.

British physicist Stephen Hawking has lived longer and achieved more than most quadriplegics have, but he's not done yet: The 70-year-old theoretician is still waiting for experimental evidence to launch him toward a Nobel Prize.

Hawking used his Nobel aspirations as a punch line more than once during his Saturday-night talk at Seattle's Paramount Theater, during a Seattle Science Festival symposium that also featured systems biology pioneer Leroy Hood and paleontologist Jack Horner. The "Luminaries Series" presentation also featured evolutionary rap and modern dance, but Hawking was clearly the headliner.

Part of Hawking's appeal is that he just keeps going, and going, and going, despite his disability. He's lived for decades with a progressively paralyzing form of amyotrophic lateral sclerosis, or ALS. His entourage includes a nurse practitioner and an aide who looks after the high-tech system that translates his cheek twitches into speech. (He and his team have been testing a more advanced system that can turn brain-wave patterns into words.)

All this work to overcome adversity wouldn't have taken Hawking so far, however, if it weren't for his crazy smarts and his sharp wit. Both were in evidence during Saturday's talk, titled "Brane New World." Hawking laid out his perspective on what he thinks could be the ultimate theory of the universe, known as M-theory.

"We have been searching for the Theory of Everything for the past 30 years, and now we think that we have found a candidate," he said.

M-theory is a "mother" theory that fuses together several strains of string theory, and allows for dimensions of space beyond the three we're familiar with. For a long time, Hawking was reluctant to accept the idea of unseen extra dimensions, but on Saturday he said everything else about M-theory made so much sense that he couldn't resist.

Ted S. Warren / AP

Stephen Hawking composes his conversations with face movements, aided by a sophisticated sensor and computer system hooked up to his wheelchair.

"I feel to ignore it would be like claiming that God put fossils in the rocks to trick Darwin into believing in evolution," Hawking said.

The big question is, why haven't we detected those darn dimensions? M-theory's proponents suggest that some forms of energy, such as light, are confined to our three-dimensional space (known as a "brane," as in membrane). Gravity, however, just might leak out of our brane — and that effect could be theoretically be detected.

The key word is "theoretically." Picking up evidence of the extradimensional effect would require high-resolution measurements of high-energy phenomena, such as the clash of binary pulsars in outer space or the smash of subatomic particles at velocities near the speed of light. No such evidence has yet come to light, despite the best efforts of gravitational-wave observatories in the U.S. and elsewhere, as well as the Large Hadron Collider on the French-Swiss border.

If astronomers were ever able to observe the behavior of black holes, that could point to the effect of extra dimensions, Hawking said. One of the biggest achievements of his career was to lay out the theory for how black holes can eventually fizzle out, due to a phenomenon known as Hawking radiation. If black holes emitted part of their energy into extra dimensions, in a form Hawking called "dark radiation," that could explain why astronomers have not yet seen the expected gamma-ray burst from a dying black hole. The alternative would be that low-mass black holes are so rare that virtually none of them have gotten small enough to die out.

"That would be a pity," he said, "because if a low-mass black hole were discovered, I would get a Nobel Prize." At that point, a giant image of the Nobel Prize medallion flashed above the stage.

It might also be possible to detect the leakage of energy into extra dimensions by creating microscopic black holes at the Large Hadron Collider, Hawking said. That phenomenon hasn't yet been observed at the LHC. Before the collider started up, there was a huge flap (and a federal court case) over fears that such micro-black holes, if created, might gobble up the planet. But Hawking said that would never happen.

"Instead, the black hole would disappear in a puff of Hawking radiation — and I would get a Nobel Prize," he said.

Before his talk, Hawking answered a few questions that were submitted by journalists (including yours truly) in advance. The topics covered some of the physicist's favorite topics, including time travel and the potential threat of an alien invasion. He also referred to his family life, which was a big part of his agenda in Seattle. One of his three children lives in the area, and over the past few days, Hawking and his family took in the King Tut exhibit at the Pacific Science Center, a boat cruise on Elliott Bay and a circus-dinner performance at Teatro Zinzanni. It all made for a great Father's Day visit to the Emerald City.

Here's the Q&A from the pre-talk press conference:

Q: What would it take to make time travel a reality, and how would that affect our present reality?

A: "We are all traveling forward in time anyway. We can fast-forward by going off in a rocket at high speed, and returning to find everyone on Earth much older or dead. Einstein's general theory of relativity seems to offer the possibility that we could warp space-time so much that we could travel back in time. However, it is likely that the warping would trigger a bolt of radiation that would destroy the spaceship, and maybe the space-time itself.

"I have experimental evidence that [backward] time travel is not possible. I gave a party for time travelers, but I didn't send out the invitation until after the party. I sat there a long time, but no one came."

Ted S. Warren / AP

Physicist and best-selling author Stephen Hawking, right, answers questions from reporters as people waiting for his public appearance look on at left at Seattle's Paramount Theater on Saturday. Hawking was taking part in a Seattle Science Festival symposium focusing on the topic of evolution. Science editor Alan Boyle ... or at least the back of his balding pate ... can be seen in the foreground.

Q: If M-theory is the only candidate for a complete theory of the universe, what’s the best evidence that you think will be found to support the theory? Lacking that evidence, isn’t M-theory merely another kind of religion?

A: "M-theory is the only theory that seems to have all the properties that we would expect of a complete and consistent theory of everything, but that may just reflect our lack of imagination. If M-theory is correct, it predicts that every particle should have a superpartner. So far we have not observed any superpartners, but the hope is that they will be found at the LHC. If they are discovered, that will be strong evidence for M-theory. On the other hand, if they are shown not to exist, that will be exciting, because then we'll learn something new."

Q: How would you describe your quality of life? What do you miss most from before the onset of ALS?

A: "Although I'm severely disabled and on a ventilator, my quality of life is pretty good. I have been very successful in my scientific work, and have become one of the best-known scientists in the world. I have three children, and three grandchildren so far. I travel widely, have been to Antarctica and have met the presidents of Korea, China, India, Ireland, Chile and the United States. I have been down in a submarine, and up in a zero-gravity flight in preparation for the flight into space that I'm hoping to make on Virgin Galactic. 

"Despite my disability, I have managed to do most things I want. My main regret is that it has prevented me from playing with my children and grandchildren as fully as I want." 

Q: John Gribbin recently argued that we are almost certainly the only intelligent life in the Milky Way –  do you think he’s right or wrong, and why? Also, SETI astronomer Seth Shostak argues that even if there are other intelligent civilizations out there, it’s too late for us to keep quiet about our existence, because it’s possible to pick up the signals we’ve sent out over the past 70 years. So isn’t it too late for us to keep quiet, and shouldn’t we be thinking about upgrading our defenses against the alien hordes?

A: "We think that life developed spontaneously on Earth, so it must be possible for life to develop on suitable planets elsewhere such as the Earth. But we don't know the probability that a planet develops life. If it is very low, we may well be the only intelligent life in the galaxy. Another frightening possibility is, intelligent life is fairly common, but that it destroys itself when it reaches the stage of advanced technology.

"Evidence that intelligent life is rare or short-lived is that we don't seem to have been visited by extraterrestrials.I am discounting claims that UFOs contain aliens. Why would they appear only to cranks and weirdos? Nor do I believe that there is some government conspiracy to conceal the evidence, and keep for themselves the advanced technologies the aliens have. If that were the case, they aren't making much use of it. Further evidence that there isn't any intelligent life within a few hundred light-years comes from the fact that SETI, the search for extraterrestrial intelligence, hasn't picked up their television quiz shows. 

"It is true that we advertise our presence by our broadcasts. But given that we haven't been visited for 4 billion years, it is unlikely that aliens will come anytime soon." 

Updates on the 'Chicken-saurus'
Hawking may have been the headliner, but he wasn't the only luminary at Saturday's "Luminaries Series" symposium on the theme of evolution. Jack Horner, who's based in Bozeman at Montana State University's Museum of the Rockies and has served as an adviser for the "Jurassic Park" movies and the "Terra Nova" TV series, brought the sellout crowd at the Paramount up to date on his quest to create a "Chicken-saurus."

"We're basically going to turn a chicken into a dinosaur," Horner said.

The idea is that the genetic code in chicken cells may still carry the instructions for producing traits that are associated with the dinosaurs from which they descended. "Birds are dinosaurs, so we don't have to 'make' a dinosaur — we already have them," Horner said. He and his colleagues are looking for ways to express those long-buried traits, known as atavisms. Even humans can express atavisms. For example, there have been cases of children born with tails.

"You don't have to do any magic," Horner told me. "You just have to find the atavisms in the genes."

Some researchers have already found the genes to produce chicken teeth, and Horner and his colleagues are methodically checking chicken embryos for avenues that could be used to create birds with long, dino-like tails or three-fingered claws like the ones sported by the velociraptors in "Jurassic Park." Horner told me that one of his students compared the effort to the Apollo moonshots.

"It's more than possible," Horner said. "It's just going to take a lot of money."

The future of medicine
In his talk, biologist Leroy Hood outlined his vision of the medical frontier. As the founder of Seattle's Institute for Systems Biology, Hood champions an approach to health care he calls P4 — predictive, preventive, personalized and participatory medicine. He said P4 medicine will arise from the convergence of revolutions in genetic analysis and data processing.

"Ten years in the future, each and every one of you will have your complete genome sequenced," Hood said. If quintillions of bytes' worth of genomic data can be used to nail down the linkages to disease factors as well as the factors that lead to wellness, it should be possible to get health care that's better as well as cheaper.

But getting the payoff from that promise depends on making the genomic data available to researchers, most likely on an anonymized basis, as well as developing the computational firepower to make sense out of a massive cloud of that data. "None of the IT companies have looked at this seriously," Hood said.

To get the ball rolling, Hood said he and his colleagues are talking with four small countries to implement P4 health-care programs in the next two or three years. Although Hood didn't name the countries, his institute already has a partnership with the Grand Duchy of Luxembourg to work on P4 initiatives.

"I have thought about going to small countries because I think the health-care system in the U.S. is too fragmented and disjointed to have any coordinated kind of change, but if you see that another country has done it very well, then that will be quite convincing," he said.

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Theoretical physicist Lawrence Krauss has taken on plenty of edgy topics, ranging from evolution to the state of science policy, to quantum quackery, to the science of "Star Trek." But in his latest book, he takes on what might be the edgiest topic of all: how all the somethingness of our universe could have arisen from nothingness without divine intervention.

The argument that God had to be the "unmoved mover," sparking the cosmos into existence, goes back to Aristotle and Thomas Aquinas. In his debates with theologians, "the question 'why is there something rather than nothing' always comes up as the one 'indefensible' issue that implies there must be a creator," Krauss told me over the weekend.

"We've come so far, that addressing that question — or at least addressing similar questions — has become a part of science," said Krauss, who heads the Origins Project at Arizona State University.

He addressed the question in a lecture that was videotaped at an Athiest Alliance International conference in 2009, and the video has been viewed more than a million times on YouTube since then. The video prompted Krauss to write his newly published book on the subject, "A Universe From Nothing."

Why is there something rather than nothing? Krauss said that question implies a search for purpose that really doesn't mesh with scientific inquiry. "The 'why' question is never really a 'why' question ... really, when we say 'why,' we mean 'how,'" he told me.

OK, so how can you get a cosmos from nothing? Krauss traces a series of discoveries building up from Einstein's general theory of relativity to the latest studies of dark energy, explaining how scientists have determined that empty space is seething with energy in the form of virtual particles. From the perspective of quantum physics, particles are popping into and out of existence all the time. The way Krauss and many other theorists see it, nothingness is so unstable that it has to give rise to something ... in our case, the universe as we know it.

What's more, Krauss and his colleagues are coming around to the view that there could be a countless succession of big bangs, creating many universes with different parameters and laws of physics. Some of the universes in this multiverse fizzle back into nothingness immediately, while others — such as ours — hang around long enough to spawn galaxies and stars, planets and life. Scientists haven't yet figured out a way to test this hypothesis, but it would explain how we're lucky enough to live in a long-lasting universe: We just happened to win the prize of existence in a cosmic lottery.

"Some people say, 'Well, that's just a cop-out,'" Krauss acknowledged. "But it's actually less of a cop-out than God."

Positives and negatives
Krauss' book isn't the only one to claim that God's not needed for the creation of the universe. British physicist Stephen Hawking, a good friend of Krauss', made a similar point in his own most recent book, "The Grand Design." A key point in the argument is that the positive energy bound up in matter is balanced by negative gravitational-field energy. From the quantum perspective, the total energy of the universe is pretty much zero. Thus, the energy of "nothingness" is conserved, even when somethingness enters the picture.

This idea of positive and negative energy balancing out at zero has sparked criticism from the creationist side of the fence, but Krauss said the concept fits with current cosmological theories.

NASA / WMAP Science Team

This graphic traces the evolution of the universe from the big bang (at left) to the present, based on data from the Wilkinson Microwave Anisotropy Probe (far right). So what gave rise to the big bang? Theoretical physicist Lawrence Krauss says addressing such questions "has become a part of science."

"It sounds like a scam," he told me. "It isn't a scam. Once you allow gravity, the amazing thing is that you can start out with zero energy and end up with lots of stuff, and that stuff can have positive energy, as long as you counteract it with negative energy. Gravity allows energy to be negative. I liken it to the difference between a very savvy stockbroker and an embezzler. The savvy stockbroker will buy on margin, and buy more stuff than they actually have money to account for. But as long as the stock goes up and they sell it in the end, no one knows the difference and everyone's happy — whereas the embezzler takes the money and of course is discovered. The universe is more like the savvy stockbroker."

In the ultra-long term, when all the galaxies have spread out in our expanding universe, and all the stars have died out, the positives and negatives cancel each other out, turning our universe back into the uniformity of empty space. "The 'somethingness' may be here for just a short time," Krauss said.

Accentuate the positive
For a lot of people, all this might sound positively soul-killing. Evolutionary biologist (and crusading atheist) Richard Dawkins says as much in his afterword to Krauss' book: "If you think that's bleak and cheerless, too bad. Reality doesn't owe us comfort."

But Krauss said he doesn't intend the book to be a downer.

"My goal is not to destroy religion, though in fact that would be an interesting side effect," he said. "It's not any more my goal than it was Charles Darwin's goal with his book ["On the Origin of Species"]. My goal is to use the hook of this fascinating question, whiich everyone asks, to motivate people to learn about the real universe." 

Krauss said a scientific perspective on the origins and the fate of the universe offers a valid alternative to the solace traditionally provided by religion.

Free Press

"A Universe From Nothing" aims to explain how something can come from nothingness in accord with the laws of physics.

"Here are these remarkable laws of nature that have arisen and produced what you never would have expected, something much more interesting than any fairy tale," Krauss said. "We are the lucky beneficiaries of that, and we should enjoy the remarkable fact that we have a consciousness that can appreciate this remarkable universe. If it's a remarkable accident, how lucky are we to be a part of it! I do think you can create a 'theology' around this if you want."

Krauss doesn't mean "theology" in the literal sense of the study of God's ways, of course, but rather in the sense of an attitude toward life and its meaning (or meaninglessness). What's your attitude? Feel free to weigh in with your comments below.

Update for 1 a.m. ET Jan. 11: I should make clear that neither Krauss nor any scientist claims to have "the answer" as to the origin of the cosmos. Theorists are just trying to figure out the possible answers to the deepest questions about the universe. Perhaps the most "remarkable" thing about all this — to borrow one of Krauss' favorite words — is that it's actually plausible for scientists to address these questions at all. (And in case you're wondering, the answer to the ultimate question is still 42.)

More about cosmic perspectives:

• Stephen Hawking says God's not needed. So?
• Richard Dawkins puts 'Magic' on a tablet
• Celebrating the spirit of Carl Sagan
• Flash interactive: Beyond the Big Bang
• Hidden universes revealed
• Cosmic Log archive on science and religion

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Want to get a head start on a mind-bending TV miniseries about space, time and the multiverse? There's an app for that.

Eight years after PBS aired "The Elegant Universe," a series based on Columbia physicist Brian Greene's best-selling book about string theory, the public-TV network is gearing up for the sequel. "The Fabric of the Cosmos," a four-parter from the "Nova" documentary team, focuses on the mysteries surrounding all the cosmic stuff that surrounds us.

The show premieres on Nov. 2, and it'll be streamed on PBS' video website — but if you have an iPhone, iPad or iPod Touch and are of a mind to download the PBS app, you can watch the first hour right now.

"Brian Greene's 'The Fabric of the Cosmos' is an amazing journey into some truly astounding theories of our universe," Jason Seiken, senior vice president for interactive, product development and innovation, said today in a news release. "On mobile, viewers get a sneak preview of the series' futuristic concepts and graphics leading up to the broadcast premiere and can continue their scientific exploration throughout the series."

It's been seven years since book version of "The Fabric of the Cosmos" was published, but the theme of the TV show is basically the same: Everything you know about space and time just might be wrong.

"We really see how our understanding of space and time from Newton until today has gone through remarkable changes," Greene told me back in 2004, "and most importantly, how so many things that we have in our intuition about space and time, their properties and so forth, are just not true to how the world actually works."

For example, consider space. Most of the universe is made up of empty space, and I'm not just talking about outer space. During the program, Greene uses computer graphics to bring the point home: If you could remove all the empty space from New York's Empire State Building, you would be left with a clump of smashed-together subatomic particles that was no bigger than a grain of rice — but still weighed hundreds of millions of pounds.

Greene isn't the only one gob-smacked by the weirdness of the space-time continuum. During the program, University of Maryland physicist S. James Gates says the nature of space "is one of the deepest mysteries in physics."

During the course of the miniseries, Greene manages to work in some of the ideas from "The Hidden Reality," the book that came after "The Fabric of the Cosmos." The last episode dwells on the concept of the multiverse — the idea that our universe might be just one of the myriads of cosmic bubbles floating in an larger extradimensional reality. Some of those bubbles might even be exactly like the one we inhabit — except, perhaps, that I'm the brainy physicist and Brian Greene is the befuddled journalist.

In this cosmic bubble, Greene and his brainy friends are planning lots of activities tied to the series. The World Science Festival, "Nova" and Columbia University have set up a special screening of the opening episode at 9 p.m. ET Nov. 2 at Columbia's Miller Theatre. After the show, the World Science Festival is planning a live webcast of a conversation with Greene and other guests, including newly named Nobel laureate Saul Perlmutter.

"Nova" has also teamed up with the American Society of Physics Students to create a special series of science cafes, focusing on the out-of-this-world ideas raised by "The Fabric of the Cosmos." Check out this map to find the nearest Cosmic Cafe. Maybe I'll see you at the Seattle event.

More about space, time and the multiverse:

• What? Could our universe be just one of many?
• Probe confirms that we live in a space-time warp
• Interactive: Looking beyond the big bang
• Can we dodge the arrow of time?
• Physics prize highlights cosmic puzzles
• Physicist introduces you to 'The Hidden Reality'
• YouTube: Brian Greene at New York Comic Con

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding me to a circle on Google+. And for something completely different, check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

M. Kornmesser / ESO

This artist's impression shows galaxies at a time less than a billion years after the big bang, when the Universe was still partially filled with hydrogen fog that absorbed ultraviolet light. New observations with the European Southern Observatory's Very Large Telescope are probing this phase of the early universe by studying the light from some of the most distant galaxies ever detected.

Two studies shed additional light on a murky question: How did the cosmic fog that enveloped the universe in its early days dissipate?

In one study, researchers suggest that whatever happened, happened quickly ... and they say it probably had to do with the hot blast of the first generation of stars. Another suggests how the fog-blasting mechanism worked ... and why it might be tricky to see the effect.

First, about that cosmic fog: Cosmologists have worked out a model for the development of the early cosmos that's a good match for their observations, and the model indicates that for the first few hundred thousand years of its existence, the universe consisted of a hot, murky stew of subatomic particles.

About 400,000 years after the big bang, things had cooled down enough for electrons and protons to come together and form a fog of neutral hydrogen gas. This marked a period that astronomers call the "Dark Ages." Eventually, gravity did its magic, and clouds of hydrogen coalesced to create the first stars and galaxies. The remaining hydrogen became electrically charged — "reionized," in geek-speak — and was cleared away.

Today, astronomers can see only as far back as the period of reionization, even if they're using the most powerful telescopes in the world. The best they can do is observe what was happening to galaxies while the reionization was taking place. And that's exactly what astronomers did during a three-year survey that's described in a research paper to be published in the Astrophysical Journal.

Timeline of the early universe
"Archaeologists can reconstruct a timeline of the past from the artifacts they find in different layers of soil. Astronomers can go one better: We can look directly into the remote past and observe the faint light from different galaxies in cosmic evolution," the project's leader, Adriano Fontana of INAF Rome Astronomical Observatory, said today in a news release from the European Southern Observatory. "The differences between the galaxies tell us about the changing conditions in the universe over this important period, and how quickly these changes were occurring."

The team conducted their survey using the ESO's Very Large Telescope in Chile. Astronomers identified five extremely faraway galaxies, based on their redshift, and placed them in a timeline that started at 780 million years after the big bang (which is thought to have occurred 13.7 billion years ago) and ended about a billion years after the big bang. They also measured how much of the galaxies' ultraviolet light was absorbed by the hydrogen fog surrounding the galaxies.

The paper's lead author, Laura Pentericci of INAF Rome Astronomical Observatory, said there was a "dramatic difference" in the amount of light blocked by the oldest vs. the youngest galaxies in the sample.

"When the universe was only 780 million years old, this neutral hydrogen was quite abundant, filling from 10 to 50 percent of the universe's volume," she said in the news release. "But only 200 million years later, the amount of neutral hydrogen had dropped to a very low level, similar to what we see today. It seems that reionization must have happened quicker than astronomers previously thought."

The findings also favor a particular hypothesis for the mechanism behind the reionization. Some theorists say the fog was cleared by radiation blazing forth from the first generation of stars, while others point to the intense radiation given off as matter falls toward black holes.

"The detailed analysis of the faint light from two of the most distant galaxies we found suggsts that the very first generation of stars may have contributed to the energy output observed," said another member of the research team, Eros Vanzella of the INAF Trieste Observatory. "These would have been very young and massive stars, about 5,000 times younger and 100 times more massive than the sun, and they may have been able to dissolve the primordial fog and make it transparent."

Confirming or disproving that hypothesis would require further observations, either from space telescopes or from better ground-based instruments such as the ESO's planned European Extremely Large Telescope.

Jordan Zastrow / Univ. of Mich.

In this three-color image of the dwarf starburst galaxy NGC 5253, green corresponds to starlight. The yellow shows the gas that is being lit up by the starburst at the galaxy's core. The red shows where ultraviolet light from massive stars is evaporating gas, exposing the central starburst along a narrow cone.

Building the case for blazing stars
Another study, published in Astrophysical Journal Letters, provides further support for the blazing-star hypothesis. Astronomers observed a dwarf starburst galaxy known as NGC 5253, about 11 million light-years away in the constellation Centaurus, using the Magellan Telescopes at Las Campanas Observatory in Chile.

NGC 5253 is nowhere near as old as the galaxies that the Italian researchers surveyed, but it does provide a clearer, closer-up view of the phenomenon that might have been at work during the reionization period. "This galaxy is nearby, but we're trying to use it to better understand what was going on in the early universe," the study's lead author, Jordan Zastrow of the University of Michigan, told me.

When Zastrow and her colleagues used special filters to analyze the light from the galaxy, they determined that extreme ultraviolet radiation was blasting out of the galaxy's center and causing hydrogen gas in the interstellar medium to dissipate. "We are not directly seeing the ultraviolet light," Zastrow emphasized in a news release. "We are seeing its signature in the gas around the galaxy."

The signature of the blast shows up in the team's color-coded picture of NGC 5253 as a reddish-yellow tail snaking out toward the lower left corner of the frame. "It appears to be happening over a very narrow region, a very narrow cone," Zastrow said.

The gas within such a galaxy would normally absorb the ultraviolet radiation, but the researchers suggest that superwinds from the galaxy's massive stars helped clear a passageway through the galactic gas, letting more of the light break through.

Starburst galaxies are rarely found in the nearby universe, but they're thought to have been very common in the early universe. NGC 5253 just might be showing astronomers a rerun of the gas-clearing process that marked the age of ionization. But the galaxy is also showing astronomers why it's been hard to see similar processes at work in other galaxies.

"The opening that is letting the UV light out is very small, which makes this light challenging to detect," Zastrow said. "We can think of it as a lighthouse. If the lamp is pointed toward you, you can see the light. If it's pointed away from you, you can't see it. We believe the orientation of the galaxy is important as to whether we can detect escaping UV radiation."

Astronomers might want to take this narrow-beam effect into account as they build their scenarios for how the cosmic fog cleared, Zastrow told me. "Particularly because this issue is so interesting, and so important for our cosmic history, the important thing is to better understand what is actually possible in terms of learning how it could have happened," she said.

More about cosmic frontiers:

• Scientists pinpoint the farthest galaxy
• Hubble spots farthest galaxy ... again
• Galactic births came early
• Scientists learn how galaxies grew up

In addition to Pentericci, Fontana and Vanzella, authors of "Spectroscopic Confirmation of Z~7 LBGs: Probing the Earliest Galaxies and the Epoch of Reionization" include M. Castellaon, A. Grazian, M. Dijkstra, K. Boutsia, S. Cristiani, M. Dickinson, E. Giallongo, M. Giavalisco, R. Maiolino, A. Moorwood and P. Santini.

In addition to Zastrow, authors of "An Ionization Cone in the Dwarf Starburst Galaxy NGC 5253" include M.S. Oey, Sylvain Veilleux, Michael McDonald and Crystal L. Martin.

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding me to your Google+ circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.

What's dark energy? In this illustration, the mysterious repulsive force is represented as a smooth purple grid that overwhelms the effects of gravity (represented by a lumpy green grid).

Most of the research recognized by a Nobel Prize has to do with solutions, but this year's physics prize highlights a problem that's been bugging scientists for more than a decade. And there may be more such problems to chew on in the years ahead.

"The way science makes progress is through an interplay between theory and observation," Sean M. Carroll, a theoretical physicist at the California Institute of Technology, told me today. But when it comes down to theory vs. observation, "observations always win," he said.

As an example, take the research that won today's Nobel Prize for physics: When the three physicists who won the award started charting the brightness of distant supernovae, they expected to find out how much the expansion of the universe was slowing down, in accord with the accepted theories for cosmic evolution. Instead, they were surprised to find that the expansion rate was speeding up.

"We thought this would be an interesting experiment to do, but we didn't know it would be this interesting," one of today's Nobel laureates, Johns Hopkins University astrophysicist Adam Riess, told journalists during a teleconference.

Physicists didn't have a good explanation in 1998 for why the cosmos should go against gravity's pull and fly apart at a faster and faster rate. And they still don't. Their best guess is that our universe has a built-in, outward-pushing feature known as dark energy, which appears in Albert Einstein's equations for relativity as a cosmological constant.

"Dark energy still looks like the right answer — the best guess, I should say," Riess said. Einstein's cosmological constant appears to account for the effect to within 10 percent accuracy, he said. But physicists are in the dark about the mechanism. It's as if you're watching a car speeding down the road, faster and faster. Riess said you might hypothesize that there's such a thing as a gas pedal, and that pressing on it was causing the speedup. But there's not yet any way to say for sure. And there's no guarantee that the speedup will continue. There might still be a let-up on the cosmic accelerator, "in which case all bets are off," Riess said.

So is this Nobel premature? Riess said it was important to note that the prize was "awarded for seeing or discovering that the universe is accelerating," rather than for explaining why.

How to crack the mystery
There are lots of experiments in the works to expand upon the discovery made by Riess and his fellow Nobel laureates, Saul Perlmutter of the University of California at Berkeley and Brian Schmidt of the Australian National University in Canberra. Just today, the European Space Agency gave its go-ahead for the 2019 launch of the $650 million Euclid space telescope, which is designed to study dark energy's effects on the large-scale structure of the universe. NASA's $1.6 billion Wide-Field Infrared Survey Telescope, or WFIRST, would also target the mystery surrounding dark energy.

But Riess suspects that the mystery can't be solved by observations alone. "We won't really resolve it until some brilliant person, the next Einstein-like person, is able to get the idea of what's going on," he said.

So he issued a plea to the theorists: "Keep working," he said. "We need your help. ... It's a very juicy problem, it's hard, and you'll win a Nobel Prize if you figure it out. In fact, I'll give you mine."

Carroll, the theorist, was sympathetic to Riess' plea. But he wasn't overly encouraging.

"You don't need to tell us that this is a big one," Carroll said. "Many of us have tried. I've tried. I've written many papers about it. But it's hard."

There are plenty of possibilities, to be sure. The acceleration could be caused by vacuum energy that doesn't vary over time, but is just a feature of empty space. It could be a slowly varying quality of the cosmos known among physicists as "quintessence." It could be some unanticipated twist in the nature of gravity, or a byproduct of multidimensional spheres of existence.

"I've spent my time on this, and I'm increasingly willing to predict that the answer is a boring one," Carroll said. Maybe the best that scientists can ever say is that this is just the way our universe works.

More deep, dark questions
For now, dark energy is just one item on a growing list of puzzling questions for big-thinking physicists — questions that also include:

• What's dark matter made out of? Observations from the past decade suggest that dark energy accounts for 74 percent of the universe's mass-energy content, and that another 22 percent consists of similarly mysterious stuff known as dark matter. So far, dark matter has been detected only through its gravitational effect, but physicists have come to assume that it takes the form of exotic subatomic particles that interact only weakly with the 4 percent of the universe we can see. Researchers had been hoping they'd see the signature of those exotic particles at the Large Hadron Collider, but so far there's been no sign.
• Where's the Higgs boson? Researchers are also looking for the Higgs boson, the last fundamental particle whose existence is predicted by the Standard Model of particle physics. Fermilab's Tevatron collider had been in the hunt until its shutdown last week, and if there's no confirmed detection hiding within the Tevatron data yet to be analyzed, it'll be up to the LHC to spot the Higgs, which is thought to be responsible for creating the mass of some subatomic particles and has been nicknamed the "God Particle." Again, there's been no sign so far, but physicists say they should know within the next year or so whether the Higgs exists. If there's no such thing, theorists might have to rewrite one of the scientific world's most successful theories.
• Why does the universe seem fine-tuned? A good number of physicists have noted that if the fundamental constants of physics had been tweaked slightly differently, life as we know it — perhaps even the universe as we know it — could not have endured for long, if at all. If you ascribe the workings of the cosmos to God, this doesn't present a problem. But this apparent "fine-tuning" poses a challenge if you're trying to explain why the universe is just so. One possibility would be to say there's a plenitude of universes out there, and we just happen to be in a universe that works pretty well. Or maybe the universe is governed by a "feedback loop" that operates forward and backward in time. Or maybe it's some sort of weird quantum phenomenon, as Stephen Hawking has proposed. As Keanu Reeves might say: "Whoa..."
• Why does time run only one way? Speaking of time's direction, Carroll's favorite conundrum has to do with why we experience time in only one direction, moving from the past into the future. In his book "From Eternity to Here," Carroll makes the case that the arrow of time moves in the same direction as entropy, from low entropy at the time of the big bang to higher entropy today, and even higher entropy tomorrow. "The question is, why was entropy low near the big bang?" Carroll said. "I'm still very much up in the air as to the answer to that question." As he studies that question, Carroll is delving into other puzzles ranging from the origin of life to the debate about free will vs. determinism. "You don't have to get into those age-old questions," Carroll admitted. "My own impulse is to enjoy those questions and get into this."
• Was Einstein wrong about the speed of light? This is one of the most recent unsettled questions for modern physics. For more than a century, the overwhelming evidence has been that Einstein's special relativity theory was correct in claiming that nothing could move faster than the speed of light in a vacuum. That's now been called into question by observations suggesting that some neutrinos achieved faster-than-light speeds during a 450-mile trip between two underground labs in Europe. Carroll said the observations are "very, very unlikely to be right," but if they are verified, that would force a radical reinterpretation of Einstein's theories.

Faster-than-light neutrinos would be far more troublesome for scientists than the speeding-up universe. As strange as the Nobel-winning supernova observations appear to be, Carroll said they actually "explain a whole bunch of things that people had been worrying about for a long while," including apparent discrepancies in measurements of the universe's age.

"Unlike the 'accelerating universe,' ... the faster-than-light neutrinos would create a whole bunch of problems to worry about," Carroll said. For example, would the phenomenon allow for backward time travel and reverse causality? Could a neutrino go back in time and "kill its grandfather"?

In a posting to the Cosmic Variance blog, Carroll floats some ideas that could get theorists out of a time-traveling jam, but it wouldn't be pretty. "If neutrinos are moving faster than light, the question is, how can we adapt special relativity to a framework which allows for this?" he said.

Riess, the experimenter, offered some advice for Carroll and his fellow theorists, based on his experience with the surprising supernova observations.

"As a lot of my colleagues say when they hear about a strange result, they go, 'Oh, that's wrong,' and usually 'How do you know?' then, 'Well, most things that are weird turn out to be wrong.' And that's true," Riess said. "But you don't want to completely close your ears and eyes to seeing weird things, because a lot of the most interesting things we see at some point were the weird things."

Tune in to 'Virtually Speaking Science'
Carroll and I will be talking about the accelerating universe, faster-than-light neutrinos and other weird and interesting things on Wednesday at 9 p.m. ET (6 p.m. PT) on "Virtually Speaking Science," an online talk show that I host on the first Wednesday of the month. You can listen to the hourlong show via BlogTalkRadio, or be a part of the audience at the Stella Nova auditorium in the virtual world known as Second Life. (Here's the SLURL for your teleporting pleasure.) You can ask questions during the show via Second Life chat or BlogTalkRadio's call-in number.

If you can't make it in real time, don't worry: The show will be archived at BlogTalkRadio as an audio podcast for on-demand listening. Many thanks to the Meta Institute for Computational Astrophysics for providing the Second Life venue.

More podcasts from 'Virtually Speaking Science':

• Rand Simberg on the private-enterprise vision for spaceflight
• Martin Hoffert on the future of energy policy
• George Djorgovski on science in virtual worlds
• Alan Stern on suborbital research and NASA's mission to Pluto
• Col. 'Coyote' Smith on the outlook for space solar power
• Tim Pickens on rocket ventures and the Google Lunar X Prize

More about the Nobel-winning research:

• Cosmic Variance: Dark energy FAQ
• Inside Science: The story behind the accelerating universe
• Life's Little Mysteries: What's dark energy? | How find was made
• Search for dark energy on msnbc.com

Carroll will also be a featured speaker for the New Horizons in Science symposium, presented Oct. 16-18 at Northern Arizona University in Flagstaff by the Council for the Advancement of Science Writing as part of ScienceWriters2011. I'm a member of the CASW board.

Connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. You can also add me to your Google+ circle, and check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds. 

If you're going to create a virtual universe, you're going to need a big computer — like the Pleiades supercomputer at NASA's Ames Research Center in California's Silicon Valley. Researchers have just made the most accurate computer simulation showing the evolution of large-scale structure in the universe, known as the Bolshoi simulation, available to astrophysicists around the world.

Bolshoi (which takes its name from the Russian word for "grand" or "big") took in data from ground-based and space-based instruments, including the best readings of the big bang's afterglow from NASA's Wilkinson Microwave Anisotropy Probe, or WMAP. Then it used 6 million CPU hours on Pleiades, ranked as the world's seventh-fastest supercomputer, to crunch all that data into a virtual representation of the universe evolving over time.

The time-lapse simulation occupies nearly 90 trillion bytes of memory, or the equivalent of nearly 10,000 typical movie DVDs.

The first two papers in a series describing the simulation have been accepted for publication in The Astrophysical Journal. "A lot more papers are on the way," one of the co-authors, physicist Joel Primack, said in a news release from the University of California at Santa Cruz.

So far, the simulation has been in close agreement with what astronomers are seeing in the actual universe.

"In one sense, you might think the initial results are a little boring, because they basically show that our standard cosmological model works," Primack said. "What's exciting is that we now have this highly accurate simulation that will provide the basis for lots of important new studies in the months and years to come."

The standard model suggests that only 4 percent of the universe's mass-energy content consists of ordinary matter — the kind that we can see. Another 22 percent is cold dark matter, which can be detected only by its gravitational influence. Physicists surmise that dark matter is made up of exotic particles that interact only weakly with ordinary matter, but they haven't yet identified any of those particles. It's the weightiness of dark matter that is thought to shape galaxy clusters into a "cosmic web," which you can easily see forming in the animation above. (Remember to go full-screen and HD for optimal effect, or check out this music-enhanced Vimeo version.)

The biggest constituent of the cosmos, at least based on current models, is dark energy: This mysterious energy, which is thought to account for around 74 percent of cosmic density, serves to counteract the force of gravity and cause the accelerating expansion of the universe. Its existence is required to reconcile cosmological theories with WMAP's observations as well as observations of distant supernovae — but no one has figured out what it is, which has led some astronomers to look for alternative theories.

Primack, who directs the University of California High-Performance Astrocomputing Center, said a close analysis of the Bolshoi simulation could help point the way to better explanations for the dark-energy effect.

"These huge cosmological simulations are essential for interpreting the results of ongoing astronomical observations and for planning the new large surveys of the universe that are expected to help determine the nature of the mysterious dark energy," he said.

The first paper based on Bolshoi analysis focuses on the role of dark-matter halos in the universe's development, while the second paper looks at Bolshoi's predictions for the abundance and properties of galaxies. The researchers have found that the simulation correctly predicts the number of galaxies as bright as our own Milky Way that have satellite galaxies as bright as the Milky Way's major satellite galaxies, the Large and Small Magellanic Clouds.

But this is just the tip of the iceberg: So far, less than 1 percent of the Bolshoi project's output has been released, Primack said. The Bolshoi simulation computes the evolution of a cubic volume measuring about a billion light-years on a side, following the interactions of 8.6 billion particles of dark matter. A variant of the simulation, called BigBolshoi or MultiDark, was run with the same number of particles in a volume 64 times larger. Another variant called MiniBolshoi is currently being run on Pleiades. It focuses on a smaller portion of the universe with higher resolution.

This all sounds pretty deep, but fortunately, the Bolshoi team has produced plenty of beautiful videos and illustrations that will delight even those who can't tell a baryon from a meson. For still more background about Bolshoi, check out the news releases from New Mexico State University, Ames Research Center and the High-Performance Astrocomputing Center.

Update for 5:50 p.m. Oct. 7: In a follow-up phone call, Primack told me that "the agreement between predictions that come from the simulations and the actual observations are really getting spectacular." The previous top-of-the-line virtual universe, known as the Millennium Simulation, showed galaxies as being "much more clustered than they actually are," he said, while the Bolshoi version is "bang-on." Primack said still more revelations are coming from the Bolshoi team. "It's like things are coming into sharp focus," he said.

More about cosmology:

• 3-D map looks at universe of 11 billion years ago
• 'Accelerating universe' could be just an illusion
• Hurry! Only a trillion years left to study the big bang
• Interactive: Beyond the Big Bang

Authors of "Halos and Galaxies in the Standard Cosmological Model: Results From the Bolshoi Simulation" include Anatoly Klypin, Sebastian Trujillo-Gomez and Joel Primack. Authors of "Galaxies in LCDM With Halo Abundance Matching: Luminosity-Velocity Relation, Baryonic Mass-Velocity Relation, Velocity Function and Clustering" include Trujillo-Gomez, Klypin, Primack and Aaron J. Romanowsky.

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding me to your Google+ circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds. 

How long does it take to simulate the Milky Way? The answer is about nine months, if you're using a powerful supercomputer. That's how long it took for researchers at the University of California at Santa Cruz and the Institute for Theoretical Physics in Zurich to produce the first simulation of galaxy formation that approximates the look of our own Milky Way spiral.

"Previous efforts to form a massive disk galaxy like the Milky Way had failed, because the simulated galaxies ended up with huge central bulges compared to the size of the disk," Javiera Guedes said today in a news release about the project.

Guedes worked on the project during her time at UC-Santa Cruz, and is now a postdoctoral researcher at the Swiss Federal Institute of Technology. She's the first author of a paper accepted for publication in the Astrophysical Journal that describes the simulation, known as the Eris galaxy.

For 20 years, astronomers have been trying to come up with a simulated galaxy that comes close to the look of the Milky Way and other spiral galaxies — but fell short of the mark. Guedes and her colleagues were more successful in part because of the computer firepower at their disposal: 1.4 million processor-hours on NASA's Pleiades supercomputer, plus additional supporting simulations at UC-Santa Cruz and the Swiss National Supercomputing Center.

"We took some risk spending a huge amount of supercomputer time to simulate a single galaxy with extra-high resolution," said UC-Santa Cruz astronomer Piero Madau, one of the paper's co-authors.

The effort used a software platform known as Gasoline to trace the motions of more than 60 million particles, representing galactic gas as well as dark matter, over the course of more than 13 billion years.

Madau said developing a realistic simulation of star formation was another key to Eris' success.

"Star formation in real galaxies occurs in a clustered fashion, and to reproduce that out of a cosmological simulation is hard," he said. "This is the first simulation that is able to resolve the high-density clouds of gas where star formation occurs, and the result is a Milky Way type of galaxy with a small bulge and a big disk."

The recipe for the Eris galaxy limited star formation to the high-density regions of the galactic disk, which resulted in a more realistic distribution of stars. Within the high-density regions, supernova explosions powered an outflow of gas from the inner part of the galaxy, keeping the central bulge from getting too big.

The point of the exercise wasn't merely to come up with a pretty animation. The virtual conditions for Eris' creation are consistent with the theory that galaxy-scale structures coalesced from cosmic webs that were dominated by cold dark matter. Gravity drew primordial clumps of dark matter together into bigger clumps, and the "ordinary" matter that makes up stars and galaxies fell into those dark-matter clumps — giving rise to visible galaxies embedded in halos of invisible dark matter.

Cosmologists contend that the universe consists of 4.6 percent ordinary matter, 23.3 percent dark matter and 72.1 percent dark energy. But the fact that astronomers found it difficult to produce galaxies like the Milky Way using that formula led some to question the prevailing cosmological model of the universe. The Eris galaxy simulation "shows that the cold dark matter scenario, where dark matter provides the scaffolding for galaxy formation, is able to generate realistic disk-dominated galaxies," Madau said.

The research team's effort may be a tour de force for supercomputing, but don't confuse the virtual Eris with the real-life Milky Way. Even though Eris is an incredibly high-resolution simulation, its 60 million particles of gas and dark matter pale in comparison with the Milky Way's hundreds of billions of stars.

Extra credit: Eris is named after the Greek goddess of discord, in recognition of the decades of discordant debate that have surrounded the scenarios for forming spiral galaxies, according to a description of the project on the HPC-CH weblog. Guedes' website includes a quote from the Iliad: "The soldiers fought like wolves while Eris, the Lady of Sorrow, watched with pleasure." The simulated galaxy isn't the first astronomy-related object to bear that discordant name: Eris is also the name given to the dwarf planet that caused so much trouble for Pluto. 

More about dark matter and cosmology:

• Has dark matter finally been seen?
• Dark-matter stars could solve cosmic mystery
• Gallery: Dark matter revealed!
• Dark matter mapped in 3-D detail

In addition to Madau and Guedes, co-authors of the paper include Simone Callegari and Lucio Mayer of the Institute for Theoretical Physics in Zurich. This research was funded by NASA, the U.S. National Science Foundation, the Swiss National Science Foundation and an ARCS Foundation fellowship to Guedes.

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding me to your Google+ circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.