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After Big Bang Came Moment of Pure Chaos, Study Finds

After Big Bang Came Moment of Pure Chaos, Study Finds
Snapshot from a computer simulation of the formation of large-scale structures in the universe, showing a patch of 100 million light-years and the resulting coherent motions of galaxies flowing toward the highest mass concentration in the center.
(Image: © ESO)

The universe was in chaos after the Big Bang kick-startedthe cosmos, a new study suggests.

While one might expect the explosion that began the universeto wreak some havoc, scientists mean something very specific when they refer tochaos. In a chaotic system, small changes can cause large-scale effects. Acommonly cited example is the "butterfly effect" ? the idea that abutterfly beating its wing in Brazil can bring about a tornado in Texas.

While past studies have suggested chaos reigned during theinfancy of our universe, the new research offers what scientists say is iron-cladargument for the case.

"The general result of this paper is that, contrary towhat some previous studies have suggested, different observers would stillagree about the chaotic nature of the universe," study leader AdilsonMotter told "Now we establish once and for all that it ischaotic."

Universal chaos? Who's asking

Previous probes into whether thenascent universe was chaotic have returned varying results. Some studies suggestedthat the answer depends on an observer's coordinates ? a person at rest in acertain time and place might make different measurements than another who wasin motion.

"The problem is ultimately related to the fact thatdifferent relativistic observers tend to perceive time differently. It means,in particular, that different scientists studying the same problem wouldconclude different things," said Motter, who is a physicist at Chicago'sNorthwestern University.

But new calculations by Motter and Katrin Gelfert ofBrazil's Federal University of Rio de Janeiro prove that this property of theuniverse is absolute regardless of an observer's relativisticcoordinates, Motter stated.That determination is based on applying Motter'scalculations to the latest cosmological models of the universe. If those modelsprove inaccurate, then the universe may turn out not to have been born inchaos, he cautioned. But all observers will agree on that result as well,according to the new findings.

"The main result is the possibility of a universaldefinition of chaos, i.e., a definition that doesn't depend of theobserver," wrote physicist Alberto Saa of Brazil's State University ofCampinas, who was not involved in the research. "This is a longstandingproblem."

A fraction of a second

According to the new study, chaos in our universe would havestarted ruling the realm about 10 to the minus 43 seconds (or 0.0000000000000000000000000000000000000000001seconds) after the BigBang. And it would have lasted only a very brief time: at least 10 to theminus 36 seconds in duration.

During this time theuniverse was expanding from its tiny, hot and dense beginnings. At anygiven time, scientists think, two of its spatial dimensions might have beenexpanding, while the third was contracting.

And this expansion, like the universe itself, was most likelychaotic, according to the new study.

"If you change just a little bit one of thecontractions, then you'd have an entirely different sequence of expansions andcontractions," Motter explained.

This period of the early universe is not well understood.Some theories propose that this early chaotic stage was followed by a period ofrapid expansion called inflation, when the universe doubled in size more than100 times within a fraction of a second.

Motter and Gelfert detailed their findings in a recent issueof the journal Communications in Mathematical Physics.

Big Crunch?

While our universe is no longer chaotic, it may return tothat state if it experiences a hypothetical Big Crunch.

Some cosmological models predict that the universe willcontinue expanding forever, or that it will gradually slow down. But it's alsopossible that it will expand, and then reverse the process and startcontracting.

The end result would be a Big Crunch, akin to the Big Bangbut in reverse. If that happens, the end of the universe ? just like itsbeginning ? will be anything but calm, researchers said.

"It would be interesting if the universe were going tocollapse again," Motter said. "In the context of our study, we canask the question of whether this re-collapse is going to be a chaotic processor not. It would most likely be chaotic."

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