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Does Time Run Backward in Other Universes?
by SCIAM
Thanks to SPS for the link.
http://www.sciam.com/article.cfm?id=the-cosmic-origins-of-times-arrow
Does Time Run Backward in Other Universes?
One of the most basic facts of life is that the future looks different from the past. But on a grand cosmological scale, they may look the same
By Sean M. Carroll
* The basic laws of physics work equally well forward or backward in time, yet we perceive time to move in one direction only—toward the future. Why?
* To account for it, we have to delve into the prehistory of the universe, to a time before the big bang. Our universe may be part of a much larger multiverse, which as a whole is time-symmetric. Time may run backward in other universes.
The universe does not look right. That may seem like a strange thing to say, given that cosmologists have very little standard for comparison. How do we know what the universe is supposed to look like? Nevertheless, over the years we have developed a strong intuition for what counts as "natural"—and the universe we see does not qualify.
Make no mistake: cosmologists have put together an incredibly successful picture of what the universe is made of and how it has evolved. Some 14 billion years ago the cosmos was hotter and denser than the interior of a star, and since then it has been cooling off and thinning out as the fabric of space expands. This picture accounts for just about every observation we have made, but a number of unusual features, especially in the early universe, suggest that there is more to the story than we understand.
Among the unnatural aspects of the universe, one stands out: time asymmetry. The microscopic laws of physics that underlie the behavior of the universe do not distinguish between past and future, yet the early universe—hot, dense, homogeneous—is completely different from today's—cool, dilute, lumpy. The universe started off orderly and has been getting increasingly disorderly ever since. The asymmetry of time, the arrow that points from past to future, plays an unmistakable role in our everyday lives: it accounts for why we cannot turn an omelet into an egg, why ice cubes never spontaneously unmelt in a glass of water, and why we remember the past but not the future. And the origin of the asymmetry we experience can be traced all the way back to the orderliness of the universe near the big bang. Every time you break an egg, you are doing observational cosmology.
The arrow of time is arguably the most blatant feature of the universe that cosmologists are currently at an utter loss to explain. Increasingly, however, this puzzle about the universe we observe hints at the existence of a much larger spacetime we do not observe. It adds support to the notion that we are part of a multiverse whose dynamics help to explain the seemingly unnatural features of our local vicinity.
The Puzzle of Entropy
Physicists encapsulate the concept of time asymmetry in the celebrated second law of thermodynamics: entropy in a closed system never decreases. Roughly, entropy is a measure of the disorder of a system. In the 19th century, Austrian physicist Ludwig Boltzmann explained entropy in terms of the distinction between the microstate of an object and its macrostate. If you were asked to describe a cup of coffee, you would most likely refer to its macrostate—its temperature, pressure and other overall features. The microstate, on the other hand, specifies the precise position and velocity of every single atom in the liquid. Many different microstates correspond to any one particular macrostate: we could move an atom here and there, and nobody looking at macroscopic scales would notice.
Entropy is the number of different microstates that correspond to the same macrostate. (Technically, it is the number of digits, or logarithm, of that number.) Thus, there are more ways to arrange a given number of atoms into a high-entropy configuration than into a low-entropy one. Imagine that you pour milk into your coffee. There are a great many ways to distribute the molecules so that the milk and coffee are completely mixed together but relatively few ways to arrange them so that the milk is segregated from the surrounding coffee. So the mixture has a higher entropy.
From this point of view, it is not surprising that entropy tends to increase with time. High-entropy states greatly outnumber low-entropy ones; almost any change to the system will land it in a higher-entropy state, simply by the luck of the draw. That is why milk mixes with coffee but never unmixes. Although it is physically possible for all the milk molecules to spontaneously conspire to arrange themselves next to one another, it is statistically very unlikely. If you waited for it to happen of its own accord as molecules randomly reshuffled, you would typically have to wait much longer than the current age of the observable universe. The arrow of time is simply the tendency of systems to evolve toward one of the numerous, natural, high-entropy states.
Read more here
http://www.sciam.com/article.cfm?id=the-cosmic-origins-of-times-arrow
Does Time Run Backward in Other Universes?
One of the most basic facts of life is that the future looks different from the past. But on a grand cosmological scale, they may look the same
By Sean M. Carroll
* The basic laws of physics work equally well forward or backward in time, yet we perceive time to move in one direction only—toward the future. Why?
* To account for it, we have to delve into the prehistory of the universe, to a time before the big bang. Our universe may be part of a much larger multiverse, which as a whole is time-symmetric. Time may run backward in other universes.
The universe does not look right. That may seem like a strange thing to say, given that cosmologists have very little standard for comparison. How do we know what the universe is supposed to look like? Nevertheless, over the years we have developed a strong intuition for what counts as "natural"—and the universe we see does not qualify.
Make no mistake: cosmologists have put together an incredibly successful picture of what the universe is made of and how it has evolved. Some 14 billion years ago the cosmos was hotter and denser than the interior of a star, and since then it has been cooling off and thinning out as the fabric of space expands. This picture accounts for just about every observation we have made, but a number of unusual features, especially in the early universe, suggest that there is more to the story than we understand.
Among the unnatural aspects of the universe, one stands out: time asymmetry. The microscopic laws of physics that underlie the behavior of the universe do not distinguish between past and future, yet the early universe—hot, dense, homogeneous—is completely different from today's—cool, dilute, lumpy. The universe started off orderly and has been getting increasingly disorderly ever since. The asymmetry of time, the arrow that points from past to future, plays an unmistakable role in our everyday lives: it accounts for why we cannot turn an omelet into an egg, why ice cubes never spontaneously unmelt in a glass of water, and why we remember the past but not the future. And the origin of the asymmetry we experience can be traced all the way back to the orderliness of the universe near the big bang. Every time you break an egg, you are doing observational cosmology.
The arrow of time is arguably the most blatant feature of the universe that cosmologists are currently at an utter loss to explain. Increasingly, however, this puzzle about the universe we observe hints at the existence of a much larger spacetime we do not observe. It adds support to the notion that we are part of a multiverse whose dynamics help to explain the seemingly unnatural features of our local vicinity.
The Puzzle of Entropy
Physicists encapsulate the concept of time asymmetry in the celebrated second law of thermodynamics: entropy in a closed system never decreases. Roughly, entropy is a measure of the disorder of a system. In the 19th century, Austrian physicist Ludwig Boltzmann explained entropy in terms of the distinction between the microstate of an object and its macrostate. If you were asked to describe a cup of coffee, you would most likely refer to its macrostate—its temperature, pressure and other overall features. The microstate, on the other hand, specifies the precise position and velocity of every single atom in the liquid. Many different microstates correspond to any one particular macrostate: we could move an atom here and there, and nobody looking at macroscopic scales would notice.
Entropy is the number of different microstates that correspond to the same macrostate. (Technically, it is the number of digits, or logarithm, of that number.) Thus, there are more ways to arrange a given number of atoms into a high-entropy configuration than into a low-entropy one. Imagine that you pour milk into your coffee. There are a great many ways to distribute the molecules so that the milk and coffee are completely mixed together but relatively few ways to arrange them so that the milk is segregated from the surrounding coffee. So the mixture has a higher entropy.
From this point of view, it is not surprising that entropy tends to increase with time. High-entropy states greatly outnumber low-entropy ones; almost any change to the system will land it in a higher-entropy state, simply by the luck of the draw. That is why milk mixes with coffee but never unmixes. Although it is physically possible for all the milk molecules to spontaneously conspire to arrange themselves next to one another, it is statistically very unlikely. If you waited for it to happen of its own accord as molecules randomly reshuffled, you would typically have to wait much longer than the current age of the observable universe. The arrow of time is simply the tendency of systems to evolve toward one of the numerous, natural, high-entropy states.
Read more here
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Posted: Friday, May 23, 2008 | PermalinkComments 1 - 50 of 50 |
Reload Comments | Back to Top | Page Numbers2. Comment #184140 by Don_Quix on May 23, 2008 at 7:03 pm
I often feel like time is running backwards in this universe. Especially after a few too many pints! Other Comments by Don_Quix
3. Comment #184143 by mordacious1 on May 23, 2008 at 7:17 pm
This is one of those areas that physicists love to speculate about. Yes, it is very interesting, in fact I love reading books about this. But...let's get our minds around multiverses first, and then we can tackle the arrow of time in those universes. Although, like I said, the speculation is great.I'm pretty convinced that in the quantum world time can run backwards. A subatomic particle can be in two places at once and move so fast that it can run into itself. But we do not know enough about even the possibilities of multiverses (sorry, repeating myself) yet.
Other Comments by mordacious1
4. Comment #184147 by Quine on May 23, 2008 at 7:27 pm
Is there a falsifiable hypothesis in there somewhere? Other Comments by Quine
5. Comment #184149 by mordacious1 on May 23, 2008 at 7:37 pm
QuineAre you referring to the article: then no.
or to my poorly worded post: probably.
Other Comments by mordacious1
6. Comment #184151 by rod-the-farmer on May 23, 2008 at 7:44 pm
This reminds me of the old joke about the question on the physics exam...Define "the universe". Give two examples.
Other Comments by rod-the-farmer
7. Comment #184159 by Quine on May 23, 2008 at 7:57 pm
mordacious1, the article; your post was perfectly fine. Other Comments by Quine
8. Comment #184175 by mordacious1 on May 23, 2008 at 8:33 pm
To me, we're getting more science topics rather than religious ones lately. I prefer the science ones, the ol' Hitler was an atheist crap was getting old. Although the posts like "In God's Name" do get my blood boiling.Other Comments by mordacious1
9. Comment #184185 by King of NH on May 23, 2008 at 9:02 pm
This is an (In God's Name) interesting article. The concept of (Hitler was an Atheist) time fascinates me, but I (Darwin recanted evolution) think there is a huge gap of understanding between what a (Dawkins is a Sinner!) scientist means by 'universe' and 'time' and what the rest of us mean.
(Atheism is a Religion)
Other Comments by King of NH
10. Comment #184192 by moderndaythomas on May 23, 2008 at 9:58 pm
I love entropy. It's apparent when I visit my sock draw. Other Comments by moderndaythomas
11. Comment #184197 by Wosret on May 23, 2008 at 10:44 pm
This isn't science, this is a lump of steaming bullshit and absurdity. This doesn't even begin to make sense. I have never actually read about the whole idea of a multiverse, but if this article underpins it, then I completely agree that this is no different than theology.
Before the big bang? But if the prevailing view (that the big bang created space and time) is true, that is a nonsensical statement. The statement presupposes the truth of his ideas.
The universe started out orderly? As far as I understand it, the prevailing view is that the universe started out in a state of maxium entropy, the complete opposite. Not to mention that order and chaos are merely projections of our ability to draw links between the interactions of phenomena, and draw probabilistic conclusions based upon them. There is no fundamental difference between the two beyond our ability to predict.
Unnatural? Now that statement really takes the cake, does he pretend to a complete and absolute knowledge of nature? That he can then decide when something is comforming or not with it? Intuitively assuming this? Like creationists intuitively assume that life is inherently unnatural? Requiring a super intelligence to constitute? What charlatan nonsense.
This all aside, time is just a lable we give the motion of matter, it is relative to its movement. It isn't really a thing at all, I wasn't aware that there was a problem.
Seems like the problem of sin, requiring the cure of salvation.
This seems to be completely pulled out of someone's ass, and doesn't appreciate the prevailing views of cosmologists. Sounds like new age non-sense, with better use of scientific lingo. They can have it.
Other Comments by Wosret
12. Comment #184199 by bucketchemist on May 23, 2008 at 10:52 pm
So, if there are universes in which time is reversed, that means that in those universes very complex phenomena can precede the existence of simple phenomena. Dawkins was wrong, Teilhard de Chardin was right, there is a God, its just that in this universe he/she/it appears at the end of time whereas elsewhere he/she/it is at the beginning. Other Comments by bucketchemist
13. Comment #184200 by mordacious1 on May 23, 2008 at 10:55 pm
MitchellActually, many cosmologists study this seriously, and it is science. It is the "what if" of science. Some black hole physicists, Hawking is one I think, but am not sure, believe that black holes can create other universes. Others believe that during the big bang, more than one universe could have been created.
Physics does not rule any of this out. The theories are there, take them or leave them, but it is real science.
Other Comments by mordacious1
14. Comment #184201 by Wosret on May 23, 2008 at 10:58 pm
They can't rule it out, that doesn't make it science. Just like ID this isn't even wrong it's useless. It can't be tested or falsified, that means it isn't science, and it claims things are unnatural.
Some cosmologists, maybe. I don't care.
Other Comments by Wosret
15. Comment #184202 by mordacious1 on May 23, 2008 at 11:01 pm
MitchellYears ago, everyone said that about black holes. Now they are accepted in the scientific community. I have to say though that multiverses will be harder to prove.
Other Comments by mordacious1
16. Comment #184203 by Wosret on May 23, 2008 at 11:05 pm
15. Comment #184202 by mordacious1
Years ago, everyone said that about black holes. Now they are accepted in the scientific community. I have to say though that multiverses will be harder to prove.
(*Sigh*) wouldn't this "argument" work equally well with any unfalsifiable or testable claim about the universe? When the hypothesis about black holes was not testable or falsifiable, it wasn't science either. Nor is this until a way to test or falsify it is forwarded. Until then, it's brain candy, nothing more.
And since this article contradicts things that are in fact supported by evidence, I'll accept the far more likely option, that this is bullshit.
Also, the whole "unnatural" claim; that is inherently impossible to falsify without omniscence.
Other Comments by Wosret
17. Comment #184206 by mordacious1 on May 23, 2008 at 11:20 pm
MitchellOh, one more thing I left out. Since String Theory is so popular nowaday, many scientists, and this does include Hawking, believe that at the quantum level, multiverses can explain the 11 or so dimensions needed to make this theory plausible.
It's been awhile since I've read up on this subject, so I'm definately speaking off the cuff here. But I don't think any serious quantum physicist can work in the field without either accepting the possibility or coming up with an alternative. Science is not just known facts, and at the quantum level I think it will one day be possible to test/falsify multiverses.
Other Comments by mordacious1
18. Comment #184211 by mordacious1 on May 24, 2008 at 12:04 am
Sean Carroll, by the way, is not some off the wall journalist but is a senior physicist at Cal Tech. I have read some of his stuff about dark energy and it is brilliant work. Of coarse, some people (Mitchell?) probably think this is science BS too. One of my favorite science topics, though.Other Comments by mordacious1
19. Comment #184213 by Christopher Davis on May 24, 2008 at 12:19 am
This is slightly related...I think.
The whole thing about a subatomic particle being able to "be" in two places at once (I believe Einstein referred to the phenomenon as "spooky action at a distance"), could that possibly be an effect of a limited ability to perceive time?
I mean suppose even with our high-tech gadgets, humans can only perceive time in some sort of discrete "packets". If something were moving quickly enough back-and-forth in space, is it possible that we could only perceive it as occupying (at a minimum) two seperate positions?
I'm not trying to be clever here, this is some shit that hit me one night after drinking about 4 pints of Guiness while reading an article similar to the one above. If anyone with a background in this field knows of something that I can read that will allow an educated layman to see why this idea is utter rubbish I'd actually appreciate it.
Other Comments by Christopher Davis
20. Comment #184214 by Wosret on May 24, 2008 at 12:23 am
It's ten dimensions, and it makes a unifying equation of physics plausible, which only works with ten dimensions, it's all on paper, and has zero actual evidence to support it.
Who gives a shit if Hawkings believes it? Does he have evidence? Seems like a fallacious appeal to authority otherwise. "Look, this smart guy believes it, thus it must be true."
Dark energy is a proposed hypothesis to explain the expansion, and total mass of the universe, and does happen to have both support, and is falsifiable, so they are hardly in the same league. It also explains an observation, which string-theory does not, it explains an invented problem, and makes an equation work.
You seem to not understand the difference.
Other Comments by Wosret
21. Comment #184215 by Wosret on May 24, 2008 at 12:27 am
19. Comment #184213 by Christopher Davis
They aren't just watching the particles move, they are also measuring them with equipement, if it were moving at such high speeds, and back and forth, then the equipement would presumably notice. (I'm a uneducated layman, but I'm just harbouring a guess here.)
Personally, I haven't the foggiest what's going on, and wouldn't even dare guess. When they figure it out I'm looking forward to hearing about it.
Other Comments by Wosret
22. Comment #184218 by robhu on May 24, 2008 at 1:26 am
Does Hawking really think that new universes are created inside black holes?I thought it was only Lee Smolin who thought that (his theory of Fecund Universes explained in The Life of the Cosmos).
IIRC while this theory is interesting (and fun I'd say) it is a long way from being a mainstream view - there is quite a lot missing from the theory to start with. I think Smolin's theory was kinda falsifiable, although I can't remember exactly how.
Mitchell seems to be right AFAICT, what is proposed in this article lacks falsifiability. We need to be very vigilant about what we consider to be good science - we really shouldn't respond wit things like "Years ago, everyone said that about black holes. Now they are accepted in the scientific community. I have to say though that multiverses will be harder to prove." as that implies that because something wasn't accepted in the past but now is that the standards for testing future things should be low. As it happens there were falsifiable tests for black holes, and they passed those tests.
"Where we have strong emotions, we're liable to fool ourselves" (Carl Sagan)
Other Comments by robhu
23. Comment #184219 by calyx on May 24, 2008 at 1:28 am
I think you are being unecessarily hostile to this idea, as you have yourself said, its just brain candy. What's so wrong with discussing this sort of thing, its interesting to me and i'm sure it is to other people too, I'm not about to say that I believe any of this, if something has no evidence to support it I won't believe it, but I can still find it interesting. On another note, it's been suggested that once that new particle accelerator get's going, in a book about string theory that I was reading the other day, they may find some new particles which will offer some circumstantial evidence for string theory.
Also I don't think im wrong in saying that the work that these people are doing on these theories and other's in the past have opened up new testable theories and are helping to advance our knowledge of the universe.
"this is no different than theology"
Which Is why I have to utterly disagree with you on that point.
Other Comments by calyx
24. Comment #184233 by lozzer on May 24, 2008 at 3:52 am
I do enjoy articles like this.It puts so much mysticisms and fantasy into reality!Makes science ever so more interesting. Other Comments by lozzer
25. Comment #184235 by Colwyn Abernathy on May 24, 2008 at 4:31 am
The basic laws of physics work equally well forward or backward in time, yet we perceive time to move in one direction onlyâ€"toward the future. Why?
Beats me...you want some toast?
Other Comments by Colwyn Abernathy
26. Comment #184236 by ferfuracious on May 24, 2008 at 4:39 am
~It would seem to be much more likely for the universe to fluctuate straight into a hot big bang, bypassing the inflationary stage altogether. Indeed, as far as entropy is concerned, it would be even more likely for the universe to fluctuate straight into the configuration we see today, bypassing the past 14 billion years of cosmic evolution.~How do we differentiate between a universe that fluctuated into inflation and one that fluctuated into its current state? They would look the same, no?
Other Comments by ferfuracious
27. Comment #184240 by Demotruk on May 24, 2008 at 5:10 am
Mitchell, nobody is asking you to believe what the author is proposing is true.Testable hypotheses don't just form fully thought out in people's heads. There is a phase in science where people have to discuss problems, possible solutions, and then try and figure out how to make them testable. Just because you can't think how to test the idea of a multiverse, doesn't mean it can't be done. We don't know how they might impact our universe, and thinking and speculating might come up with an answer.
Now, if he tried to get it into classrooms without testing it, or even tried to convince other scientists of it's truth without creating a testable hypothesis, he would be acting unscientifically. But then, if in an academic arena, whenever a new idea is proposed, you were to shout "that's untestable, bullshit!!" without giving it due thought, you wouldn't be acting very scientific. An idea can evolve into a hypothesis with further discussion and thought. Why would you try to stifle that?
I'm not saying I agree with his hypothesis. I'm not sure if his criticism of inflation is fair. But I'm not going to immediately cry bullshit either.
Other Comments by Demotruk
28. Comment #184241 by Brian English on May 24, 2008 at 5:19 am
I've read that Goedel worked out that there is no time (as in one event following the next). Because according to relativity theory, all time is equally existant. Or as Einstein said, time is a persistant illusion.... Other Comments by Brian English
29. Comment #184244 by julianstirling on May 24, 2008 at 5:49 am
Firstly"Technically, it is the number of digits, or logarithm, of that number."
Number of digits? You are thinking of log base 10 not the natural log! It is the number of times you would have to multiply 2.7182818.... by itself to get the number of micro states. Then times by Boltzmann's constant 1.38x10^-23. (My thermodynamics exam was this week, I couldn't let that rest!)
NEXT
"I love entropy. It's apparent when I visit my sock draw."
Rearranging macroscopic objects does not increase the number of accessible microstates, therefore no change in entropy!
NEXT
"They can't rule it out, that doesn't make it science. Just like ID this isn't even wrong it's useless. It can't be tested or falsified, that means it isn't science, and it claims things are unnatural. "
Before you can test a theory in science you have to have a workable hypothesis, then you look at ways to test it. Once the hypothesis really comes together there may be certain predictions about the universe it can make. It is stupid to rule out something because it is at the edge of what we understand, if we did that science would never progress.
NEXT
"Oh, one more thing I left out. Since String Theory is so popular nowaday...."
It depends on who you talk to, many physicists think string theory is crap now, as one of it's only tested predictions was out by a larger factor than any other experiment in the history of science (120 orders of magnitude). And normally when they get a prediction, then they end up finding they have thousands of equally possible predictions. I am not saying it is wrong, it is just far less popular than the TV says it is.
Other Comments by julianstirling
30. Comment #184247 by sb84 on May 24, 2008 at 5:59 am
Mitchell, I think the scientists who work on this are actually trying to find ways to make it falsifiable. That's one big difference with theology. It may turn out not to be falsifiable, but at least they can work on it for a while.I think one of the main points here is simply that if your theories allow for something that doesn't occur in the presently observable universe, you have to account for that. Either there is a reason why it doesn't happen (like a "law of entropy"), or there is no such reason and you have to deal with the possibility that somewhere else things work differently.
And if you say "yes, there is a law of entropy" then you owe it to yourself to try and explain it. Otherwise (at least in the eyes of many) you are just describing and not explaining.
[edit] To clarify: not that there is anything intrinsically wrong with "just" describing; maybe that is all we can really do. But if you believe that the job of science is to "explain", then I think you have to go all the way.
Other Comments by sb84
31. Comment #184251 by the great teapot on May 24, 2008 at 7:06 am
Do winkimtots have snort werzels?Other Comments by the great teapot
32. Comment #184252 by RobDinsmore on May 24, 2008 at 7:07 am
Rearranging macroscopic objects does not increase the number of accessible microstates, therefore no change in entropy!
Although this statement may have some validity with respect to the sock drawer comment, it is not universally true. If those macroscopic objects effect the energetics of the system then all bets are off.
I also have a comment on the article. What the hell is this that it can pass as a piece of scientific journalism. "Time may run backwards" OK what would that even mean? Not even a hint is provided and then they go on to talk about entropy without even giving a simple reason for why high entropy states are more probable. They use the old all the gas in the room never goes to the corner argument incorrectly. Mixing milk into coffee is a nonequilibrium process. You cannot talk about the entropy until the cold milk you just poured into your hot coffee has had time to come to thermal equilibrium. After that occurs then you can use the "gas" argument. There really is no need to be sloppy when trying to explain science in lay terms.
And again what would time moving backwards even mean? Does it mean that all things tend towards order because fluctuations only happen in one direction or that fluctuations do not even happen? It's hard to read something like this and take it seriously if they don't even hint at the consequences.
Other Comments by RobDinsmore
33. Comment #184254 by TruthByEvidence on May 24, 2008 at 7:30 am
It's interesting to think of time as a tangible force as opposed to a simple perception of biological life.I personally believe that time is a perception of gradual change in the cosmos... yet since we are constructs of that same cosmos, why do we only see time one way?
When you think of time as being different based upon the gravitational fields in the area of space, it becomes a more fascinating force than a simple Earth clock.
It becomes something that CAN be altered and manipulated...based upon gravity that has an effect on dimensions that has an effect on our perception of four of those spatial dimensions.
(The fourth is spacetime, if I am not incorrect.)
This sort of science inspires me so! I wish I knew Michio Kaku, Paul Davies, Steven Weinberg and Stephen Hawking personally...
*tear*
I suppose these articles show that Richard Dawkins still has a passion for these physics as well! How fun is that!
Other Comments by TruthByEvidence
34. Comment #184280 by riki on May 24, 2008 at 9:41 am
Nah time is an illusion. btw who's got the remote?http://video3000.de/
Other Comments by riki
35. Comment #184281 by julianstirling on May 24, 2008 at 9:44 am
"Although this statement may have some validity with respect to the sock drawer comment, it is not universally true. If those macroscopic objects effect the energetics of the system then all bets are off."May have some validity? It IS true, and there is no doubt about that. By rearranging socks how much heat energy is being transferred into out our of the system? 0, therefore Î"S=0.
The only heat changes will be to the agents moving them, therefore increasing the entropy of the universe.
There is no tendency for macroscopic objects to become more disorderly by them selves.
Have a look at: http://jchemed.chem.wisc.edu/Journal/Issues/1999/Oct/abs1385.html
It is the link our lecturer gave us when complaining about the misuse of the second law.
Other Comments by julianstirling
36. Comment #184282 by mordacious1 on May 24, 2008 at 9:48 am
"a measure of disorder or randomness in a closed system" is one definition of entropy. So, as long as the sock drawer remains closed...Other Comments by mordacious1
37. Comment #184284 by steveroot on May 24, 2008 at 10:00 am
34. Comment #184280 by riki on May 24, 2008 at 9:41 am
Nah time is an illusion.
Lunchtime doubly so.
-D.A.
Ste5e
Other Comments by steveroot
38. Comment #184304 by hopeful on May 24, 2008 at 12:54 pm
Comment #184197 by Mitchell GilksMitchell, I can't help feeling that you have fallen into the trap of automatically ripping this article to shreds just because there are so many articles that DO deserve to be ripped to shreds.
Some articles are just interesting.
Other Comments by hopeful
39. Comment #184308 by Quine on May 24, 2008 at 1:06 pm
Hi, julianstirling, thanks for your interesting link in comment #184281. I have also remarked about the general confusion between "information entropy' and "physical entropy" especially as it has come up in discussions with creationists who try to use (but in fact misuse) the second law to prove that evolution by Natural Selection could not generate new information.However, Lambert goes too far in his zeal on this when he states that there is no connection or overlap. There is overlap in special situations, and macro implications as shown in the famous work by Edward Fredkin and Tommaso Toffoli circa 1980. This is now being used to design adiabatic logic in microprocessors to reduce the waste heat produced in information processing.
Other Comments by Quine
40. Comment #184320 by zbob on May 24, 2008 at 2:37 pm
On the subject of the illusory nature of time from the perspective of absolute spacetime:Albert Einstein stated that "since there exists in the four dimensional structure (space-time) no longer any sections which represent "now" objectively, the concepts of happening and becoming are indeed not completely suspended but yet complicated. It appears therefore more natural to think of physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence." Einstein went on to state that there is not a true division between past and future, but rather a single existence. In other words, the distinction between past, present and future is an illusion.
Since all subjective time is relative depending on the observer's speed through space relative to another observer and their relative position in the universe, there is no objective, absolute time or absolute space as Newton proposed. Instead, since there is no objective "now" due to the relative, subjective observation of space-time, the only thing that is real is the whole of space-time. As theoretical physicist David Bohm stated: "Ultimately, all moments are really one. Therefore now is eternity" Or as theoretical physicist Brian Greene says: "Just as we envision all of space as really being out there, as really existing, we should also envision all of time as really being out there, as really existing too."
And for a different view of the second law of thermodynamics and the nature of order and timelessness go to:
http://www.everythingforever.com/
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41. Comment #184341 by qomak on May 24, 2008 at 5:44 pm
Just to throw my two cents, I generally agree with Mitchell here. The problem with the article is that for the average person it is indistinguishable from a crackpot article putting forward hypotheses for a pseudoscience.
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42. Comment #184344 by mmurray on May 24, 2008 at 5:58 pm
qomak:The problem with the article is that for the average person it is indistinguishable from a crackpot article putting forward hypotheses for a pseudoscience.
Except they can check the source and see it is Scientific American which is reasonably reputable.
Michael
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43. Comment #184362 by Simonw on May 24, 2008 at 7:24 pm
I'm with Mitchell.My theoretical physics degree didn't go so well. But the article is terribly written. I suspect there may be good science behind it, but if so it was all lost in the simplification that took place for appearing in SciAm.
Sure time asymmetry is an interesting property of the Universe, but it may simply be the Universe evolving in the most probably direction.
My rule of thumb is never to trust anyone who talks about entropy, who doesn't start of by defining the borders of the systems they are talking about, and supplying some equation to explain how entropy increased or decreased in each system.
For example describing the early universe as uniform, and then claiming it had low entropy, seems contradictory. A gas evens out in a given volume so that it is evenly spread, which represents a high entropy state. I'm sure the author had something particular in mind, but he didn't convey it to me.
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44. Comment #184410 by ThoughtsonCommonToad on May 25, 2008 at 3:56 am
Before the Big Bang - Roger Penrose
http://www.youtube.com/watch?v=ghbDGBOYp1g&hl=en
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45. Comment #184415 by qomak on May 25, 2008 at 5:02 am
mmurrayExcept they can check the source and see it is Scientific American which is reasonably reputable.
That's not the issue really. The issue is about the language used in this article. In other words, if you present science in the language of pseudoscience, then do be surprised when a significant percentage of the population confuse science with pseudoscience.
So what's the language of pseudoscience? It's basically very similar to the language used by scientists except that there is no mention of proof, hypothesis or testability.
Example:
A chakra is a center of activity that
receives, assimilates, and expresses life force energy. The word chakra literally translates as wheel or disk and refers to a spinning sphere of bioenergetic activity emanating from the major nerve ganglia branching forward from the spinal column. There are six of these wheels stacked in a column of energy that spans from the base of the spine to the middle of the forehead. And the seventh which is beyond the physical region. It is the six major chakras that correlate with basic states of consciousness...
Sounds impressive doesn't it? In fact, it's painfully difficult to explain to people who buy these things why this Chakra theory is nonsense while trying to defend the "nonsense" mentioned in this article. From experience, if you try your method (saying that SA is reputable) then you'll often get accused of circular logic (i.e., judging the content by the journal and the journal by the content) and having a bias against pseudoscience.
The point is scientists who are trying to combat pseudoscience then they should try to stand above it ALL THE TIME. For example, in this article a few humble sentences about testability and falsifiability could do the trick.
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46. Comment #184927 by dloubet on May 26, 2008 at 12:56 pm
The whole article is easily falsifiable. Just provide an example of an egg putting itself back together and entrophy is falsified.Other Comments by dloubet
47. Comment #185793 by dogofman on May 28, 2008 at 2:42 pm
Reply to 2. Comment #184140 by Don_QuixOh I would want it run backwards really badly.
One could have prevented som things to happen and one could have had a few more pints.
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48. Comment #187712 by elcapitanp on June 2, 2008 at 1:23 pm
I don't really understand the term 'disorganized' and thus don't understand entropy. If the early universe has the same number of microstates as the modern universe, who is to say which macrostate is more organized? To me, it is like saying that a new deck of cards is more organized than a shuffled one. That only makes sense from the standpoint of a human observer. Outside of human subjectivity, one configuration of a deck of cards is the same as another configuration. If all of the cells in my body were to rearrange, we might say "That is a disorganized configuration." But what if all the cells were to organize into some form that was intelligible to humans? If I spontaneously morphed into a donkey, one might say "That is a different, yet still organized, configuration." I just don't see how one configuration can be called disorganized instead of just "differently organized."Other Comments by elcapitanp
49. Comment #188718 by ultraviolet on June 4, 2008 at 12:11 pm
Here's an article from Carroll in a peer-reviewed journal if you all want the more "scientific" treatment of the content of this article.http://arxiv.org/abs/hep-th/0410270
or search scholar.google.com:
"Spontaneous Inflation and the Origin of the Arrow of Time"
Authors: Sean M. Carroll, Jennifer Chen
It really seems pointless to me to nitpick on the language in an article meant for an educated lay audience (non-scientists!). If you consider yourself a scientist, you should know to look at the peer-reviewed stuff before you nitpick. A SciAm article is meant to be accessible to my grandma.
and elcapitanp - I'm still a student in this regard, but I can recommend looking up Boltzmannian distribution (try H-Theorem) for a better understanding of how, from a historical perspective, the idea of "disorganized" has evolved. Gibbs then updated the ideas and Maxwell further, but to my understanding it has to do with how many different ways microstates can be distributed to result in the same macrostate. Somebody more educated please correct me if I'm off-base. Happy hunting!
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50. Comment #188810 by Lemniscate on June 4, 2008 at 3:50 pm
Mitchell, you're wrong about the universe starting out in a state of maximum entropy. According to http://en.wikipedia.org/wiki/Heat_death_of_the_universe:
"Inflationary cosmology suggests that in the early universe, before cosmic expansion, energy was uniformly distributed, and thus the universe was in a state superficially similar to heat death. However, the two states are in fact very different: in the early universe, gravity was a very important force, and in a gravitational system, if energy is uniformly distributed, entropy is quite low, compared to a state in which most matter has collapsed into black holes. Thus, such a state is not in thermal equilibrium, and in fact there is no thermal equilibrium for such a system, as it is thermodynamically unstable. However, in the heat death scenario, the energy density is so low that the system can be thought of as non-gravitational, such that a state in which energy is uniformly distributed is a thermal equilibrium state, i.e., the state of maximal entropy."
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1. Comment #184129 by kram50 on May 23, 2008 at 6:14 pm
This is a litle too much for me to get my head around! Very interesting indeed though.I have been amazed all my life at the vastness of space and every now and then I have a mini freak-out just thinking about it.
I can't believe that we are the only planet that supports life!!
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