An infant universe, born before we knew

An infant universe, born before we knew
Astronomers released the latest and most exquisite baby picture yet of the universe on Thursday, one that showed it to be 80 million to 100 million years older and a little fatter, with more light and dark matter than previously thought, and perhaps ever so slightly lopsided.

Recorded by the European Space Agency's Planck satellite, the image is a heat map of the cosmos as it appeared only 370,000 years after the Big Bang, showing space speckled with faint spots from which galaxies would grow over billions of years.

The map, the Planck team said in news conferences and in 29 papers posted online on Thursday morning, is in stunning agreement with the general view of the universe that has emerged during the past 20 years, of a cosmos dominated by dark energy that is pushing it apart and dark matter that is pulling galaxies together. It also shows a universe that seems to have endured an explosive burp known as inflation, which was the dynamite in the Big Bang.

In a statement issued by the European Space Agency, Jean-Jacques Dordain, its director-general, said, "The extraordinary quality of Planck's portrait of the infant universe allows us to peel back its layers to the very foundations, revealing that our blueprint of the cosmos is far from complete."

Marc Kamionkowski, an astrophysicist at Johns Hopkins University who commented on the work at a news teleconference sponsored by NASA, called Planck "cosmology's human genome project," saying, "It shows the seeds from which the current universe grew."

David N. Spergel, a Princeton University cosmologist, described the new results "beautiful," adding that "the standard cosmological model looks even stronger today than yesterday. The universe remains simple and strange."

Within the standard cosmological framework, however, the new satellite data underscored the existence of puzzling anomalies that may yet lead theorists back to the drawing board. The universe appears to be slightly lumpier, with bigger and more hot and cold spots in the northern half of the sky as seen from Earth than toward the south, for example. And there is a large, unexplained cool spot in the northern hemisphere.

Those anomalies had shown up on previous maps by NASA's Wilkinson Microwave Anisotropy Probe, or WMAP, satellite, but some had argued that they were because of a bad analysis or contamination from the Milky Way.

Now cosmologists will have to take them more seriously, said Max Tegmark, an expert on the early universe at the Massachusetts Institute of Technology who was not part of the Planck team and who termed the new results "very exciting."

It could be, he said, that "the universe is trying to tell us something."

George Efstathiou of Cambridge University, one of the leaders of the Planck project, said in the European Space Agency news release: "Our ultimate goal would be to construct a new model that predicts the anomalies and links them together. But these are early days; so far, we don't know whether this is possible and what type of new physics might be needed. And that's exciting."

The Planck satellite was launched in 2009 and has been scanning the sky ever since, recording the faint variations in a haze of radio microwaves that fill the sky.

Microwaves are a form of electromagnetic radiation used in the kitchen for heating leftovers; that they are important for cosmology was discovered by accident back in 1965 by a pair of Bell Labs radio astronomers, Arno Penzias and Robert W. Wilson, who later won the Nobel Prize in Physics. Using balloons, a U-2 spy plane and a series of satellites like the WMAP, astronomers have been teasing out the detailed features of this radiation.

The microwaves detected by the Planck date from 370,000 years after the Big Bang, which is as far back as optical or radio telescopes will ever be able to see, cosmologists say. But the patterns within them date from less than a trillionth of a second after the Big Bang, when the universe is said to have undergone a violent burst of expansion known as inflation that set cosmic history on the course it has followed ever since. Those patterns are Planck's prize.

Analyzing the relative sizes and frequencies of spots and ripples has allowed astronomers to describe the birth of the universe to a precision that would make the philosophers weep.

The new data have allowed astronomers to tweak their model a bit. It now seems the universe is 13.8 billion years old, instead of 13.7 billion, and consists by mass of 4.9 percent atoms, 27 percent dark matter and 71 percent dark energy.

The biggest surprise here, astronomers said, is that the universe is expanding slightly more slowly than previous measurements had indicated. The Hubble constant, which characterizes the expansion rate, is 67 kilometers per second per megaparsec - the units astronomers use - according to Planck. Recent ground-based measurements combined with the WMAP data gave a value of 69, offering enough of a discrepancy to make cosmologists rerun their computer simulations of cosmic history.

The fact that astronomers once would go to war with one another over a factor of two in measurements of this parameter shows how cosmology has progressed over the past 20 years.

Pressed for a possible explanation for the discrepancy, Martin White, a Planck team member from the University of California, Berkeley, said it represents a mismatch between measurements made of the beginning of time and those made more recently. He said it could mean that dark energy, which is speeding up the expansion of the universe, is more complicated than cosmologists thought. He termed the possibility "pretty radical," adding, "That would be pretty exciting."

The data also offered striking support for the notion of inflation, which has been the backbone of Big Bang theorizing for 30 years.

Under the influence of a mysterious force field during the first fraction of a second, what would become the observable universe ballooned by 100 trillion trillion times in size from a subatomic pinprick to a grapefruit in less than a violent eye-blink, according to the story first enunciated by Alan Guth of MIT.

Submicroscopic quantum fluctuations in this force field are what would produce the hot spots in the cosmic microwaves, which in turn would grow into galaxies. According to Planck's measurements, those fluctuations so far fit the predictions of the simplest model of inflation, invented by Andrei Linde of Stanford, to a T.

Tegmark of MIT said, "We're homing in on the simplest model."

Cosmologists still do not know what might have caused inflation, but the recent discovery of the Higgs boson has provided evidence that the kinds of fields that can provoke such behavior really exist.

Tegmark and others said that another clue to the nature of inflation could come from the anomalies in the microwave data, which tend to happen on the largest scales in the universe. By the logic of quantum cosmology they were the first patterns to be laid down on the emerging cosmos - that is to say, when inflation was just starting.

He compared it to walking in someplace and encountering a fight. If the fight has been going on for a while, he said, it is impossible to tell who started it or who was hurt first. But if you come in only a few seconds after it started, you have a better chance of figuring out who did what to whom.

"It may be," he said, "we're coming in early to the cosmic brawl." 
© 2013, The New York Times News Service

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