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Scientists zero in on why time flows in one direction
eurekalert/University of Chicago ^ | 26-Oct-2004 | Steve Koppes

Posted on 10/26/2004 7:36:36 PM PDT by ckilmer

Public release date: 26-Oct-2004 [ Print This Article | Close This Window ]

Contact: Steve Koppes skoppes@uchicago.edu 773-702-8366 University of Chicago

Scientists zero in on why time flows in one direction The big bang could be a normal event in the natural evolution of the universe that will happen repeatedly over incredibly vast time scales as the universe expands, empties out and cools off, according to two University of Chicago physicists. "We like to say that the big bang is nothing special in the history of our universe," said Sean Carroll, an Assistant Professor in Physics at the University of Chicago. Carroll and University of Chicago graduate student Jennifer Chen are scheduled to post a paper describing their ideas at http://arxiv.org/ Thursday evening.

Carroll and Chen's research addresses two ambitious questions: why does time flow in only one direction, and could the big bang have arisen from an energy fluctuation in empty space that conforms to the known laws of physics?

The question about the arrow of time has vexed physicists for a century because "for the most part the fundamental laws of physics don't distinguish between past and future. They're time-symmetric," Carroll said.

And closely bound to the issue of time is the concept of entropy, a measure of disorder in the universe. As physicist Ludwig Boltzmann showed a century ago, entropy naturally increases with time. "You can turn an egg into an omelet, but not an omelet into an egg," Carroll said.

But the mystery remains as to why entropy was low in the universe to begin with. The difficulty of that question has long bothered scientists, who most often simply leave it as a puzzle to answer in the future. Carroll and Chen have made an attempt to answer it now.

Previous researchers have approached questions about the big bang with the assumption that entropy in the universe is finite. Carroll and Chen take the opposite approach. "We're postulating that the entropy of the universe is infinite. It could always increase," Chen said.

To successfully explain why the universe looks as it does today, both approaches must accommodate a process called inflation, which is an extension of the big bang theory. Astrophysicists invented inflation theory so that they could explain the universe as it appears today. According to inflation, the universe underwent a period of massive expansion in a fraction of a second after the big bang.

But there's a problem with that scenario: a "skeleton in the closet," Carroll said. To begin inflation, the universe would have encompassed a microscopically tiny patch in an extremely unlikely configuration, not what scientists would expect from a randomly chosen initial condition. Carroll and Chen argue that a generic initial condition is actually likely to resemble cold, empty space-not an obviously favorable starting point for the onset of inflation.

In a universe of finite entropy, some scientists have proposed that a random fluctuation could trigger inflation. This, however, would require the molecules of the universe to fluctuate from a high-entropy state into one of low entropy-a statistical longshot.

"The conditions necessary for inflation are not that easy to start," Carroll said. "There's an argument that it's easier just to have our universe appear from a random fluctuation than to have inflation begin from a random fluctuation."

Carroll and Chen's scenario of infinite entropy is inspired by the finding in 1998 that the universe will expand forever because of a mysterious force called "dark energy." Under these conditions, the natural configuration of the universe is one that is almost empty. "In our current universe, the entropy is growing and the universe is expanding and becoming emptier," Carroll said.

But even empty space has faint traces of energy that fluctuate on the subatomic scale. As suggested previously by Jaume Garriga of Universitat Autonoma de Barcelona and Alexander Vilenkin of Tufts University, these flucuations can generate their own big bangs in tiny areas of the universe, widely separated in time and space. Carroll and Chen extend this idea in dramatic fashion, suggesting that inflation could start "in reverse" in the distant past of our universe, so that time could appear to run backwards (from our perspective) to observers far in our past.

Regardless of the direction they run in, the new universes created in these big bangs will continue the process of increasing entropy. In this never-ending cycle, the universe never achieves equilibrium. If it did achieve equilibrium, nothing would ever happen. There would be no arrow of time.

"There's no state you can go to that is maximal entropy. You can always increase the entropy more by creating a new universe and allowing it to expand and cool off," Carroll explained.

### Images of the authors are available upon request.

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TOPICS: Culture/Society; Miscellaneous; Philosophy
KEYWORDS: bluesky; ghengiskhan; immanualkant; navel; philosphy; physics; science; skyblue; stringtheory; time
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1 posted on 10/26/2004 7:36:37 PM PDT by ckilmer
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To: ckilmer

because that's the way the clock hands go!


2 posted on 10/26/2004 7:37:32 PM PDT by eyespysomething (Idealism is fine, but as it approaches reality the cost becomes prohibitive.)
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To: eyespysomething

Plus, it always flows downhill.


3 posted on 10/26/2004 7:38:11 PM PDT by TheBigB (Please Lord...let Bush win and I promise...no naughty thoughts about Lindsay Lohan for a week.)
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To: eyespysomething

Time: Nature's way of keeping everything from happening at once!

Mark


4 posted on 10/26/2004 7:38:27 PM PDT by MarkL (Power corrupts. Absolute power corrupts absolutely. But it rocks absolutely, too!)
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To: ckilmer

Now if they could only figure out why voter fraud only flows in favor of the Democrats...


5 posted on 10/26/2004 7:38:28 PM PDT by CurlyBill (Voter Fraud is one of the primary campaign strategies of the Democrats!)
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To: TheBigB

Yeah, gravity!


6 posted on 10/26/2004 7:39:37 PM PDT by Sam Cree (Democrats are herd animals)
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To: MarkL

LOL!!
Soooo THAT'S the reason....

:)... what a great line..


7 posted on 10/26/2004 7:40:27 PM PDT by JesseJane (~On November 2, keep in mind what mattered most on 9-11.~)
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To: ckilmer
""You can turn an egg into an omelet, but not an omelet into an egg," Carroll said. "

Try feeding the omelet to a chicken.

8 posted on 10/26/2004 7:40:29 PM PDT by bayourod (Old Media news is poll driven, not event driven, not fact driven, not newsworthy driven.)
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To: ckilmer
Nahhh, time is circular.

And where would a discussion thread about time be without, "Time flies like the wind. And fruit flies like bananas."
9 posted on 10/26/2004 7:40:38 PM PDT by Chummy (RepublicanAttackSquad.biz: "A vote 4 Kerry is a vote 4 Osama")
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To: Sam Cree
My head hurts now...must go back and re-watch my Schoolhouse Rock tapes...

"Down, down, down, down, Graaaa-aaavi-teee..."

10 posted on 10/26/2004 7:40:39 PM PDT by TheBigB (Please Lord...let Bush win and I promise...no naughty thoughts about Lindsay Lohan for a week.)
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To: ckilmer

That's assuming dimension Time flows ... it might also just be oriented in a fashion 'like' past is linear, present is planar, and future is volumetric.


11 posted on 10/26/2004 7:41:06 PM PDT by MHGinTN (If you can read this, you've had life support from someone. Promote life support for others.)
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To: ckilmer

"Scientists blah blah blah, blah blah blah, blah blah-blah, blah-blah-blah..."

If I had a nickel...


12 posted on 10/26/2004 7:41:23 PM PDT by ApesForEvolution (You will NEVER convince me that Muhammadanism isn't a veil for MASS MURDERS. Save your time...)
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To: eyespysomething
Steve Miller figured this out years ago...

"Time keeps on slippin', slippin', slippin' Into the future Time keeps on slippin', slippin', slippin' Into the future...

I want to fly like an eagle To the sea Fly like an eagle Let my spirit carry me I want to fly like an eagle Till I'm free..."

13 posted on 10/26/2004 7:41:36 PM PDT by Mad Mammoth
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To: eyespysomething

man, time only flows in ONE direction? Oh man, you learn sumfin new every day!


14 posted on 10/26/2004 7:42:24 PM PDT by drhogan
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To: ckilmer
If it didn't it would slosh.
15 posted on 10/26/2004 7:42:25 PM PDT by Lady Jag (Used to be sciencediet but found the solution)
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To: ckilmer

ping


16 posted on 10/26/2004 7:42:25 PM PDT by HawaiianGecko (Member of the PajamaNati for 1/6th of a year)
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To: Mad Mammoth

Hey, isn't that the new Kerry ad? You now, with the ostrich and the eagle?


17 posted on 10/26/2004 7:42:51 PM PDT by eyespysomething (Idealism is fine, but as it approaches reality the cost becomes prohibitive.)
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To: eyespysomething

except in the southen hemisphere


18 posted on 10/26/2004 7:43:01 PM PDT by HawaiianGecko (Member of the PajamaNati for 1/6th of a year)
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To: bayourod
"Try feeding the omelet to a chicken."Try promoting a sovereign America border concept without pandering to illegal invaders?
19 posted on 10/26/2004 7:43:05 PM PDT by ApesForEvolution (You will NEVER convince me that Muhammadanism isn't a veil for MASS MURDERS. Save your time...)
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To: ckilmer

Just think we all get to pay for this drivel thanks to government grants.


20 posted on 10/26/2004 7:43:23 PM PDT by carlr
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To: eyespysomething

Well, the coyote ate the ostrich, so we're down to just an eagle! LOLOLOL!


21 posted on 10/26/2004 7:43:43 PM PDT by ApesForEvolution (You will NEVER convince me that Muhammadanism isn't a veil for MASS MURDERS. Save your time...)
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To: ckilmer

Good post; pathetic theory.

Entropy is unusable energy, not necessarily disorder. The Big Bang theory defies our laws of physics, so that sort of event probably never happened. Time won't run backwards just because the universe starts contracting, etc...

22 posted on 10/26/2004 7:44:07 PM PDT by Southack (Media Bias means that Castro won't be punished for Cuban war crimes against Black Angolans in Africa)
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To: ckilmer

Good read: "In Entropy's Jaws" by Robert Silverberg.


23 posted on 10/26/2004 7:44:26 PM PDT by glock rocks (I'm not sure what Van Helsing is shooting, but I want one)
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To: ckilmer

It's a part of Karl Rove's evil plan to prevent liberals from changing the past.


24 posted on 10/26/2004 7:45:11 PM PDT by FreedomCalls (It's the "Statue of Liberty," not the "Statue of Security.")
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To: ApesForEvolution

lol, why are they wasting money on that ad here in GA?

Lol, we shouldn't have trashed this thread. Bad FReepers.


25 posted on 10/26/2004 7:45:42 PM PDT by eyespysomething (Idealism is fine, but as it approaches reality the cost becomes prohibitive.)
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To: carlr
"Just think we all get to pay for this drivel thanks to government grants."

Just wait until you find out how much of your money the igits in Wash. D.C. send to Yessir Itispigfat and his PLO/PLA/Terror Works 4 Us, Inc. !
26 posted on 10/26/2004 7:45:54 PM PDT by ApesForEvolution (You will NEVER convince me that Muhammadanism isn't a veil for MASS MURDERS. Save your time...)
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To: ckilmer

Time is only a perception. It doesn't really exist.


27 posted on 10/26/2004 7:45:59 PM PDT by Se7eN
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To: RadioAstronomer

Interesting


28 posted on 10/26/2004 7:46:05 PM PDT by RadioAstronomer
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To: ckilmer

All I know is that in my younger years I often wished fervently that I could make time flow backwards - usually when I woke up with a girl who somehow was far less attractive than she was at last call.


29 posted on 10/26/2004 7:46:10 PM PDT by AggieCPA (Howdy, Ags!)
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To: Se7eN
Time is only a perception. It doesn't really exist.

Tell that to my boss.

30 posted on 10/26/2004 7:46:40 PM PDT by eyespysomething (Idealism is fine, but as it approaches reality the cost becomes prohibitive.)
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To: TheBigB

I believe you are correct. High energy state to lower. FWIW my dog doesn't tell time or care. I envy her.


31 posted on 10/26/2004 7:47:20 PM PDT by mad_as_he$$ (Never corner anything meaner than you. NSDQ, De Opresso Liber.)
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To: eyespysomething

LOL

Baaaaaaaad FReepers....


32 posted on 10/26/2004 7:47:38 PM PDT by ApesForEvolution (You will NEVER convince me that Muhammadanism isn't a veil for MASS MURDERS. Save your time...)
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To: HawaiianGecko

It flows the opposite direction in the northern hemisphere.


33 posted on 10/26/2004 7:47:45 PM PDT by NCC-1701 (ISLAM IS A CULT, PURE AND SIMPLE!!!!! IT MUST BE ERADICATED FROM THE FACE OF THE EARTH.)
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To: ckilmer
Carroll and Chen's research addresses two ambitious questions: why does time flow in only one direction?

How do they know it does? Perhaps we only perceive it flowing in one direction only because we're in an accelerated frame of reference with respect to time.

34 posted on 10/26/2004 7:47:51 PM PDT by Oberon (What does it take to make government shrink?)
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To: eyespysomething
And furthermmore...sometimes it seems like the last 2 minutes of a football game takes a bit longer than 2 actual minutes...I blame Bush.
35 posted on 10/26/2004 7:48:02 PM PDT by TheBigB (Please Lord...let Bush win and I promise...no naughty thoughts about Lindsay Lohan for a week.)
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To: ApesForEvolution

In the beginning God . . . .


36 posted on 10/26/2004 7:48:04 PM PDT by Rodm (Seest thou a man diligent in his business? He shall stand before kings)
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To: AggieCPA

Coyote ugly?


37 posted on 10/26/2004 7:48:33 PM PDT by ApesForEvolution (You will NEVER convince me that Muhammadanism isn't a veil for MASS MURDERS. Save your time...)
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To: TheBigB
I question the timing of this study.
38 posted on 10/26/2004 7:49:05 PM PDT by eyespysomething (Idealism is fine, but as it approaches reality the cost becomes prohibitive.)
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To: ckilmer

If time could move frontwards and backwards, John Kerry could take back his unvoting for the $87 billion before his voting for it. Does that make sense?


39 posted on 10/26/2004 7:49:10 PM PDT by eagle11 (If you value America's future.....vote GWBush on Nov 2nd!!!)
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To: ckilmer; TaxRelief
You can always increase the entropy more by creating a new universe and allowing it to expand and cool off," Carroll explained.

Oh, wow! I think we'll try this for a science project tomorrow!

40 posted on 10/26/2004 7:49:35 PM PDT by Tax-chick (I'm not making this up.)
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To: ckilmer

My first reaction to the headline "SAY WHAT?"


41 posted on 10/26/2004 7:49:43 PM PDT by GeronL (FREE KERRY'S SCARY bumper sticker .......... http://www.kerrysscary.com/bumper_sticker.php)
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To: eagle11

yes, in a Kerry sort of way


42 posted on 10/26/2004 7:50:06 PM PDT by HawaiianGecko (Member of the PajamaNati for 1/6th of a year)
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To: ckilmer

Science has a way of claiming to have all the answers of history, and yet it has not satisfactorily defined time itself.


43 posted on 10/26/2004 7:50:21 PM PDT by Fester Chugabrew
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To: Tax-chick

Just keep your universe away from mine...at least until yours is potty trained...lol


44 posted on 10/26/2004 7:51:04 PM PDT by ApesForEvolution (You will NEVER convince me that Muhammadanism isn't a veil for MASS MURDERS. Save your time...)
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To: eyespysomething
*groan*

Make your time!

45 posted on 10/26/2004 7:51:26 PM PDT by TheBigB (Please Lord...let Bush win and I promise...no naughty thoughts about Lindsay Lohan for a week.)
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To: eyespysomething

If there have been Big Bangs over and over again, then does that mean that John Kerry could have run for President an infinite number of times before? And that future versions of ourselves might have to suffer the same indignity for eternity? AAAGH!!!


46 posted on 10/26/2004 7:51:36 PM PDT by WestVirginiaRebel (What does John Kerry hunt with? Spitballs???)
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To: Tax-chick
Try the Philadelphia experiment , it's too kewl for words!!
47 posted on 10/26/2004 7:51:37 PM PDT by timestax
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To: bondserv

pingus timus


48 posted on 10/26/2004 7:52:05 PM PDT by Fester Chugabrew
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To: ckilmer

When they can explain how matter created itself, I will listen. Until then, they are whistling in the dark.


49 posted on 10/26/2004 7:52:15 PM PDT by cynicom (<p)
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To: ckilmer

They are correct, the big bang has little (nothing) to do with the making of our universe. I love reading how scientists go back and forth proving each other's theory wrong and trying very hard not to mention the "C" word. Almost laughable. BEsides, if this theory was correct, there would be a lot more "life" as a result of the numerous Big Bangs and billions of years to for that life to "evolve". Such nonsense to even think that we came from a speck of dust. By the way, where did the speck of dust come from?


50 posted on 10/26/2004 7:52:50 PM PDT by Right in Wisconsin
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