TIME astronomy

New Picture: The Universe as a Sulky Adolescent

Portrait of the universe as a young man
Portrait of the universe as a young man

An ingenious technique reveals data that's been lost for 11 billion years

Presidential tracking polls are famous for their speed—a gaffe at noon is reflected in the numbers by four. That’s because a poll is not a lengthy conversation with voters, but just a quick-hit piece of data-gathering repeated over and over. The same approach now appears able to give us answers about the universe, too.

Using just four hours of telescope observation time, astronomers have generated a new image of what part of the universe looked like in its adolescence, when it was less than a quarter of its current age. The three-dimensional map, published in The Astrophysical Journal Letters, measures millions of light years across and reveals regions of high-density matter representing galaxies as they were barely 3 billion years post-Big Bang.

“We’ve pulled this off a decade before anyone else thought it was possible,” said Max Planck postdoctoral researcher Khee-Gan Lee, the paper’s lead author.

Astronomers had previously believed they would need far more observation time and more-powerful telescopes than are currently available to collect sufficient starlight from distant galaxies with which to do a job like this. That’s partly because those light sources appear up to 15 billion times dimmer than the very faintest stars that can be seen with the naked eye.

But four hours on the Keck I telescope at the Keck Observatory on Mauna Kea, Hawaii turned out to be enough. The scientists used a technique similar to a CT scan to create their map. But rather than taking cross-sectional x-rays through a body to generate a 3D image, they used light from background galaxies passing through hydrogen gas in the “cosmic web”—the tangle of macro-filaments in which the universe’s matter arranges itself—to do the same thing.

The reason they didn’t need the most sensitive equipment available to do this work was because they had a powerful algorithm instead, created by graduate student Casey Stark and physics and astronomy professor Martin White, both of the University of California, Berkeley. The data they gathered might have been noisy but the algorithm cleaned it right up. The resulting map, says Ohio State University professor of astronomy David Weinberg, is “fine enough that it’s revealing a lot of the interesting details.”

Adds Harvard astronomy professor Daniel Eisenstein, “For a lot of questions, this is a very useful scale of a map.”

The map’s elongated, plank-like shape reflects one admitted constraint of the study: because of bad weather and the short data collection time, the astronomers could map only a limited volume of space. The next order of business is for Keck I to cover a larger patch of sky, revealing huge swathes of the adolescent universe. From this map astronomers will not just be able to see the appearance of the cosmos a short while after the Big Bang, but also tease out a little bit of information about the clumping of matter that allowed galaxies to form in some regions while leaving others empty.

Next-generation super-telescopes will no doubt be useful for both these questions, able to quadruple the density of the data as well as help scientists figure out how the universe looked even closer to the Big Bang than 11 billion years ago. For now, though, telescopes like Keck I will tell us plenty. “Noisy data doesn’t scare me,” Lee said.

TIME space

Cosmic Deflation: Doubts Raised Over Blockbuster Big Bang Study

Big bang
A discovery that provided evidence for the Big Bang Theory is being called into question Brand X Pictures via Getty Images

A major new study claimed to find direct evidence of the Big Bang and the theory of cosmic inflation. But now scientists aren't so sure

It was just weeks ago that astronomers announced a major, double-barreled discovery: using a super-sensitive microwave telescope known as BICEP2, they had seen evidence of gravity waves that roiled the cosmos before it was a billionth of a trillionth of a second old. That was part one; part two was that the observed gravity waves strongly confirmed the theory of cosmic inflation—that the entire universe went into warp overdrive, expanding faster than the speed of light for the tiniest fraction of a second.

It was Nobel-level work, no doubt about it—provided it was true. But from the moment it was announced at a high-profile press conference, outside scientists had their doubts. There was reason to suspect, they said, that the Harvard-led team might actually have detected nothing more exciting than interstellar dust in the Milky Way. And now a paper expected to go online today, written by Raphael Flauger, of New York University and the Institute for Advanced Study in Princeton, puts those doubts in writing.

The signal may still be from the dawn of time, he writes. But it might equally well be what Princeton University astrophysicist David Spergel calls “schmutz” (in precisely that language: it’s what the Urban Dictionary defines as the Yiddish term “used by Jewish mothers to identify that you’ve got some kind of crap on your face.”) “At this point,” says Spergel, “I’m convinced that they haven’t made a discovery.”

It’s not that anyone doubted the integrity or ability of the Harvard-led team that claimed the discovery. “These guys are no slouches,” says Lyman Page, chair of Princeton’s physics department. “This is a good group. If there’s a problem here, it’s one of enthusiasm.”

And who wouldn’t be enthusiastic? The theory of inflation seemed downright nutty when it was first proposed in the early 1980s by Alan Guth, now at the Massachusetts Institute of Technology. But it explained some mysteries that had stumped astrophysicists for decades, including why the universe looks essentially the same in all directions, and why galaxies and clusters of galaxies are distributed the way they are.

Since then, every observation of the early universe has been consistent with the idea of cosmic inflation–most notably, the ultra-precise maps of microwaves left over from the Big Bang made by the WMAP satellite in 2003. (Both Spergel and Page were involved in that piece of cosmic cartography.) But the BICEP2 measurement was in principle more definitive than most; beyond that, there are many competing versions of inflation theory, and the new results suggested that one of the simplest versions was the right one.

The problem: the signal predicted by inflation is something called polarization, a sort of twisting of electromagnetic radiation. And while it can come from inflation-triggered gravity waves, microwaves from the early universe are altered en route to earthly telescopes, and if you don’t allow for the alteration, you can mistake local dust for a signal from billions of years ago. To correct for dust, the BICEP2 team relied, not on its own observations, but on data from Europe’s Planck satellite. The data were preliminary, however, and the BICEP2 team got them data, not from a database, or even a scientific paper, but from a slide shown at a conference by the Planck team. “It’s all we had to work with,” says Harvard astrophysicist John Kovac, who led the BICEP2 team. Moreover, he says, the Planck slide affects only one of the six models his team to characterize interstellar dust. “That’s wrong,” says Spergel. “It affects five out of the six.”

All of this will be settled within months, as other teams weigh in with their own results—not just Planck, whose formal paper on cosmic dust will be coming out in the fall, but also a host of ground-based and balloon-based microwave telescopes that were racing with BICEP2 to look for evidence of gravity waves themselves. That’s exactly how science should work, says Kovac. “We were primarily focused on getting our measurements out to the scientific community,” he says, and the challenges that follow are a normal part of the scientific process.

Traditionally, peer review of a new result—especially such an important one—doesn’t normally happen in such a public way, and some scientists have criticized the Harvard-Smithsonian Center for Astrophysics (CfA) for holding a press conference to tout it before other scientists have had a chance to weigh in. Christine Pulliam, a public affairs officer at the CfA disagrees. “A finding this profound would have been publicized with or without a press conference,” she told TIME. “By holding one, the team was able to convey all relevant information as a coherent whole, with the appropriate caveats that further research is needed.”

There’s another issue, however, says Princeton’s Paul Steinhardt (a proponent of a theory that competes with inflation, it should be noted—a theory that would be ruled out by the detection of primordial gravity waves) “The BICEP2 team keeps talking about waiting for ‘confirmation’ of their detection. But you cannot confirm unless you first detect. Shouldn’t the record be set straight?”

TIME Cosmology

Cosmic Bulletins: Two Major Discoveries Rock Science

Telescope BICEP2 (in the foreground) and the South Pole Telescope (in the background) in Antarctica, on March 31, 2007.
Telescope BICEP2 (in the foreground) and the South Pole Telescope (in the background) in Antarctica, on March 31, 2007. Steffen Richter—Harvard University/EPA

Nearly a century ago, Einstein came up with the idea of gravitational waves. Now, in a discovery that physicists are calling "extraordinary" and "spectacular," observers at the South Pole have found the first direct evidence they exist

The Theory of General Relativity seemed truly bizarre when Albert Einstein first articulated it 99 years ago: gravity, the great physicist declared, was no longer to be seen as a force, but rather as the warping of “spacetime,” an amalgam of those two formerly independent concepts. The theory also predicted that violent events should trigger gravitational waves, which would set spacetime rippling, like a vat of cosmic jello. There has been some circumstantial evidence of those ripples, involving changes in orbits of binary stars, but what’s always been missing is a smoking gun, direct observational measurement of a gravitational wave.

The same is true of the Inflationary Universe theory, postulated in the 1980s: just .0000000000000000000000000000000000001 seconds (give or take) after the Big Bang, the theory said, the cosmos underwent a burst of expansion so furious that it was briefly flying apart faster than the speed of light. Exceeding light speed is supposed to be impossible, except that that law applies only to something moving through spacetime, not spacetime itself expanding. Just as with gravitational waves, there’s plenty of reason to think it really happened, but again, no proof.

Not until now, anyway. In a discovery physicists are calling “huge,” “extraordinary” and “spectacular,” a team of observers using a microwave-sensitive telescope at the South Pole has found the first direct evidence of gravitational waves—and the strongest proof of inflation to date, all in one shot. “When I got the call,” says Marc Kamionkowski, a theorist at Johns Hopkins University who wasn’t involved in the research, “I had to ask if it was real. To me, this is bigger than the Higgs boson.” If it’s confirmed by other groups, says Avi Loeb, chair of the Harvard astronomy department and also not a participant in the research, “it’s worth a Nobel.”

According to Kamionkowski, one of few physicists allowed to see the scientific paper before it was announced at a press conference today, that confirmation is likelier than not. “These are extremely careful and conservative people,” he says of the team that made the observation. “They’ve had this evidence for three years, looked at every alternative explanation for what they were seeing, and systematically ruled them out one by one.”

For a finding of this enormity, the critical bit of evidence John Kovac of the Harvard-Smithsonian Center for Astrophysics and his colleagues saw seems entirely innocuous: a slight distortion in microwave radiation left over from the Big Bang. These microwaves didn’t even exist until about 400,000 years after the Big Bang happened, far later than the inflationary scenario—which occurred before the universe had aged even a billionth of a trillionth of a quadrillionth of a second—could have played out. But when the microwaves did pop into existence, the cosmos should have still been jiggling with gravitational waves set off by the violence of the inflation. Spot the jiggles and you prove both the expansionary phenomenon and the existence of the waves left over from it.

That’s what Kovac and his colleagues did, though it wasn’t literally jiggles that they saw. Instead they noticed that the background radiation was polarized, its waves of electromagnetic energy oscillating not in random directions but in just a few specific ones. (Sunlight also oscillates in random directions; polarizing sunglasses work by letting in only the rays within a narrow range of orientations.) That microwave polarization suggests that something was shaking the radiation this way or that.

The telescope the researchers used—the Background Imaging of Cosmic Extragalactic Polarization 2, or BICEP2, instrument—is tuned to see the critical kind of polarization in background radiation, but there was no guarantee it ever would. Inflation theory comes in several versions, all of which posit different intensities. “In some,” says MIT’s Alan Guth, who was one of the inflationary universe theory’s original inventors, “the waves are so weak they could never be detected. To see them turn up is beautiful.”

What made the gravitational waves—and thus the polarization they caused—so powerful has to do with why the universe inflated in the first place. Physicists like Guth had already theorized that inflation would happen as the cosmos transitioned from one energy state to another, much as water changes to ice. That transition released huge amounts of energy, which turbocharged the already-expanding universe. Also like water, which goes from vapor to liquid to solid, the post-Big Bang universe went through several such transitions, all during the first fraction of a fraction of a second of its life.

The amount of polarization—dictated by the strength of the gravitational waves—suggest that the transition that triggered the high-speed inflation occurred when the universe was at the so-called grand unified scale. That’s the point at which electromagnetism, the weak nuclear force and the strong nuclear force, all of which have vastly different strengths and effects today, were a single force. “It represents about a trillion times the energy scale produced by the Large Hadron Collider,” says Loeb, referring to the world’s biggest accelerator, where the Higgs was found.

The new results, assuming they’re verified, now rule out some of the more complicated, exotic versions of inflation, which seemed favored by cruder measurements made last year by the European Planck satellite. “Some people liked those,” says Guth, “because they got to write complicated papers about them.” But in physics, simpler ideas are usually considered more elegant.

Also ruled out by the detection of gravitational waves, according to both Guth and Loeb, is at least one of the few viable alternatives to the Big Bang. Known as the ekpyrotic universe model, it posits that the cosmic microwaves we’ve been detecting since the 60’s came from the titanic collision between two “branes”—short for membranes—which were independent universes (one of which was ours) floating around in higher-dimensional space.

The new results do have to be verified. Even though the BICEP2 team methodically checked and rechecked its work to rule out any mistakes, nobody, including Kovac and his colleagues, can be 100 percent certain until independent groups, using their own instruments, see the polarization signal too. That shouldn’t take long, given that cosmologists at Princeton, Berkeley, the University of Minnesota, the Goddard Spaceflight Center, the University of Chicago and more were already in the hunt. “Whether it’s correct or incorrect“ says Kamionkowski, who strongly favors the former, “will be known very quickly.”

Meanwhile, the BICEP2 team has already started taking data with a more powerful telescope called the Keck Array, also at the South Pole, and is hard at work building yet another, called BICEP3, which will begin flexing its muscles next summer. Extraordinary as the new results are, they’re just a taste of the science that will come out of these new instruments. “I’ve made 23 trips to the Pole in my career so far,” says Kovac, “and I’ll be making a lot more.” It’s a long, cold journey—but to understand the first moments of cosmic creation, it’s clearly worth it.

More: The Sights And Sounds Of The Solar System From NASA’s Deep Space Network

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