CAN TIME EXIST WITHOUT ENTROPY?

[MrMrdevincamus]

Not really.

Please expand~

 

[Revoltingest]

I couldn't remember the web site that used the breaking glass example s\but I found this quickly; From the web; There's no fundamental law of nature that prevents us from un-breaking eggs. In fact, physics says that any event in our day-to-day lives could happen in reverse, at any time.

Well again there is an arrow of time but at the same time physicists say our current physical law does not forbid the arrow time pointing 'back' or 'forward'. Lastly the theory of time and of entropy are not yet well sorted out, I mean they are both theory and still are changing.

Entropy is pretty well understood....it's not a theory, but rather an observation
expressed as the 2nd law of thermodynamics. This same law is what prevents
re-assembly of eggs & glasses, ie, additional energy is required to perform the work.

If a physicist claims that time could just start going in reverse, I'd be really
interested in seeing an example....something meaningful, ie, on the macro scale.

 

[MrMrdevincamus]

I voted yes. Time can only be perceived when there is entropy/change, but say we have two particles, one which changes from time to time and one which doesn't - does time then only exist for the changing one? Why would it, they are in the same system. Take away the changing particle and observe only the unchanging. You can't "count" anymore how much time has passed by watching it, but that doesn't mean that no time has passed since removing one particle shouldn't make such a change.

Yes thought provoking....maybe time flows over or bypasses the particle that does not change. Time does not effect if it does its not measurable, an object in or at the event horizon of a super massive gravity well or an object that attains the speed of light (if it could attain the velocity of c)....

 

[PureX]

Pssssst...don't tell Einstein that! Time is a dimension, and therefore it exists just as surely as east west and north does. However I have read several books that say time may not exist*. However for this thread it does exist. As I pointed out hinting that entropy may allow time to exist. Without entropy would time be in our vocabulary? I feel we humans create the illusion of time, by that I mean time as in 't' (lower case is the symbol I have seen used for intuitive time).

* (from the web)... Efforts to understand time below the Planck scale have led to an exceedingly strange juncture in physics. The problem, in brief, is that time may not exist at the most fundamental level of physical reality. If so, then what is time? And why is it so obviously and tyrannically omnipresent in our own experience? “The meaning of time has become terribly problematic in contemporary physics,” says Simon Saunders, a philosopher of physics at the University of Oxford. “The situation is so uncomfortable that by far the best thing to do is declare oneself an agnostic.” (from the web)

Time is a type of perceived experience of reality, not a reality unto itself. We humans have a lot of difficulty understanding the fundamentals of reality because we cannot grasp the whole of it, and understand the totality of it's interconnection. We can't separate our limited and relative experience of reality from our cognitive conceptual construct of reality. We cannot transcend our own small place in the whole, so as to "see" the whole as it really is.

 

[MrMrdevincamus]

Entropy is pretty well understood....it's not a theory, but rather an observation
expressed as the 2nd law of thermodynamics. This same law is what prevents
re-assembly of eggs & glasses, ie, additional energy is required to perform the work.

You are right about the 2nd law being an exception however entropy was a theory when I was in school, maybe it has changed?

; {>

 

[Revoltingest]

You are right about the 2nd law being an exception however entropy was a theory when I was in school, maybe it has changed?

; {>

From the Wikipedia article on the 2nd law....
"The first theory of the conversion of heat into mechanical work is due to Nicolas Léonard Sadi Carnot in 1824. He was the first to realize correctly that the efficiency of this conversion depends on the difference of temperature between an engine and its environment.

Recognizing the significance of James Prescott Joule's work on the conservation of energy, Rudolf Clausius was the first to formulate the second law during 1850, in this form: heat does not flow spontaneously from cold to hot bodies. While common knowledge now, this was contrary to the caloric theory of heat popular at the time, which considered heat as a fluid. From there he was able to infer the principle of Sadi Carnot and the definition of entropy (1865)."
Did you attend school before 1900?
That would explain its being taught as a "theory".

 

[Polymath257]

I couldn't remember the web site that used the breaking glass example s\but I found this quickly; From the web; There's no fundamental law of nature that prevents us from un-breaking eggs. In fact, physics says that any event in our day-to-day lives could happen in reverse, at any time.

Well again there is an arrow of time but at the same time physicists say our current physical law does not forbid the arrow time pointing 'back' or 'forward'. Lastly the theory of time and of entropy are not yet well sorted out, I mean they are both theory and still are changing.

Most of the fundamental physical laws look the same with time flowing 'backwards' as for it flowing 'forwards'. So, at the level of fundamental particles, things would look the same both ways. This is true *except* for some very rare reactions involving the weak nuclear force. As far as I have been able to see, there is no connection between this weak force and entropy increase in one direction of time.

That said, one way of interpreting the second law is to say that things are going from less probable to more probable. The quantum states are becoming more evenly distributed, or, equivalently, the phase space taken up is spread out more evenly.

The problem with this is that the *actual* phase space *cannot* spread out because of a result known as Louiville's theorem. Alternatively, time evolution in quantum mechanics is 'unitary', which means total probabilities are maintained.

So, again, there is something going on here concerning information loss when looking at things macroscopically instead of microscopically. That information loss *is* the entropy. It also seems to be related to the fact that macroscopic treatments are 'blurry': they don't keep track of the specific particle trajectories, which is why the phase space volumes seem to increase (instead of staying the same a la Louiville's theorem).

You had linked time slowing at the boundary of a black hole with entropy, and that is wrong (probably). The reason is that the event horizon of a black hole contains the *maximum* possible entropy for its area, not the minimum.

As for un-breaking an egg: possible under the known laws, but incredibly unlikely. And that gets to the fact that the second law is a *statistical law* and not a fundamental law. We do know of cases (involving small numbers of particles) where the total entropy can decrease spontaneously. But those are random fluctuations. Such become less and less likely with more particles. Once you have a mole of particles (macroscopic), the likelihood is very, very close to zero.

 

[Polymath257]

From the Wikipedia article on the 2nd law....
"The first theory of the conversion of heat into mechanical work is due to Nicolas Léonard Sadi Carnot in 1824. He was the first to realize correctly that the efficiency of this conversion depends on the difference of temperature between an engine and its environment.

Recognizing the significance of James Prescott Joule's work on the conservation of energy, Rudolf Clausius was the first to formulate the second law during 1850, in this form: heat does not flow spontaneously from cold to hot bodies. While common knowledge now, this was contrary to the caloric theory of heat popular at the time, which considered heat as a fluid. From there he was able to infer the principle of Sadi Carnot and the definition of entropy (1865)."
Did you attend school before 1900?
That would explain its being taught as a "theory".

A lot depends here on exactly what is meant by the 'second law'. The pure thermodynamic law is well established, but not a fundamental law. Once we get into statistical mechanics, we realize that the 2LOT is a statistical law: it is very, very unlikely that in a macroscopic system heat with flow spontaneously from cold to hot. It isn't technically impossible. And, in systems with small numbers of particles, violations have been observed.

 

[shunyadragon]

Entropy is about the direction of time, not its existence.

Without a direction in time entropy would not exist, ie before the beginning of our universe.

 

[Revoltingest]

A lot depends here on exactly what is meant by the 'second law'. The pure thermodynamic law is well established, but not a fundamental law. Once we get into statistical mechanics, we realize that the 2LOT is a statistical law: it is very, very unlikely that in a macroscopic system heat with flow spontaneously from cold to hot. It isn't technically impossible. And, in systems with small numbers of particles, violations have been observed.

It's a "macro" law.
And since the macro is so huge, the probability that it would be violated
is vanishingly small, ie, prkactically impossible.
Remember that I'm a mechanical engineer....macro is all that matters.
I don't even consider the multiverse when designing gear trains.

I once really understood classical thermo....it was among me favorite
courses....aced'm all. The subject was just so gosh darn elegant.
Now I can barely remember the stuff.

 

[Revoltingest]

Without a direction in time entropy would not exist, ie before the beginning of our universe.

Think of it this way.....
Entropy makes time a vector, ie, it has magnitude & direction.
Without entropy, time could go either way, so it just lacks direction, making it scalar.

OK....terrible analogy cuz magnitude doesn't apply well.
Here's another way to see it.....

Time is a relationship between matter, energy, & location, eg, F=MA, V=D/T, E=.5MVV, chemical reactions
Let's say you have 2 bricks.
One is warm, the other cold.
They're touching each other, & nothing else.

Now....
1) Entropy dictates that heat transferred from the warm to cold brick.
This takes time to occur.
Then the heat stays where it is because all is in equilibrium.
(The "zeroth law of thermo states that heat flows from hot to cold.)

2) With no entropy, the heat could go back & forth between the bricks.
This would also take time, but time would flow in alternating directions.

 

[Polymath257]

There is an old paradox of entropy:

First, suppose you have two different gases separated by a barrier (same temperature and pressure) and open the barrier. 2LOT dictates that the gases will mix, which increases the entropy.

Second, suppose you have a barrier, but have the *same* gas on either side of the barrier. In this case, opening the barrier *doesn't* change the entropy. The gases are the same, so 'mixing' is meaningless.

Third, suppose you have a barrier separating two gases, but you cannot detect the differences: for all you know, the gases are the same. Now what happens? if entropy goes up, there is no way to calculate by how much. You see the gases as the same, so you calculate no entropy increase. But if you could *detect* an entropy increase, then you would know the gases are different!

The upshot is that *both* ways of calculating work in practice: if you work with gases you think are not distinguishable and are never able to distinguish them, then the calculation with zero entropy change will stay consistent with observations. If, instead, you work with the entropy change due to two different gases, that will ALSO be consistent as long as you keep the gases straight in your calculations.

This, to me, says that there is a lot about entropy that is convention. But *clearly* 't all convention because heat goes from hot to cold and not the other way around (spontaneously, net effect, etc).

 

[shunyadragon]

Think of it this way.....
Entropy makes time a vector, ie, it has magnitude & direction.
Without entropy, time could go either way, so it just lacks direction, making it scalar.

OK....terrible analogy cuz magnitude doesn't apply well.
Here's another way to see it.....

Time is a relationship between matter, energy, & location, eg, F=MA, V=D/T, E=.5MVV, chemical reactions
Let's say you have 2 bricks.
One is warm, the other cold.
They're touching each other, & nothing else.

Now....
1) Entropy dictates that heat transferred from the warm to cold brick.
This takes time to occur.
Then the heat stays where it is because all is in equilibrium.
(The "zeroth law of thermo states that heat flows from hot to cold.)

2) With no entropy, the heat could go back & forth between the bricks.
This would also take time, but time would flow in alternating directions.

Mostly agree, but before the beginning of our universe none of this existed, neither did time.

 

[Revoltingest]

Mostly agree, but before the beginning of our universe none of this existed, neither did time.

Now you're getting even farther above my pay grade.
Before the universe existed, I've no idea what there was.

A speculation....
Let's say there was a bunch'o space, but there was
no matter or energy....& no virtual particles either.
Since time is a relationship between location, mass &
energy, there'd be no way to detect it even if it did exist.

 

[shunyadragon]

Now you're getting even farther above my pay grade.
Before the universe existed, I've no idea what there was.

A speculation....
Let's say there was a bunch'o space, but there was
no matter or energy....& no virtual particles either.
Since time is a relationship between location, mass &
energy, there'd be no way to detect it even if it did exist.

Stephan Hawking the beginning of our universe and the beginning of time.

From: The Beginning of TIme

"At this time, the Big Bang, all the matter in the universe, would have been on top of itself. The density would have been infinite. It would have been what is called, a singularity. At a singularity, all the laws of physics would have broken down. This means that the state of the universe, after the Big Bang, will not depend on anything that may have happened before, because the deterministic laws that govern the universe will break down in the Big Bang. The universe will evolve from the Big Bang, completely independently of what it was like before. Even the amount of matter in the universe, can be different to what it was before the Big Bang, as the Law of Conservation of Matter, will break down at the Big Bang.

Since events before the Big Bang have no observational consequences, one may as well cut them out of the theory, and say that time began at the Big Bang. Events before the Big Bang, are simply not defined, because there's no way one could measure what happened at them. This kind of beginning to the universe, and of time itself, is very different to the beginnings that had been considered earlier. These had to be imposed on the universe by some external agency. There is no dynamical reason why the motion of bodies in the solar system can not be extrapolated back in time, far beyond four thousand and four BC, the date for the creation of the universe, according to the book of Genesis. Thus it would require the direct intervention of God, if the universe began at that date. By contrast, the Big Bang is a beginning that is required by the dynamical laws that govern the universe. It is therefore intrinsic to the universe, and is not imposed on it from outside.

The conclusion of this lecture is that the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago. The beginning of real time, would have been a singularity, at which the laws of physics would have broken down. Nevertheless, the way the universe began would have been determined by the laws of physics, if the universe satisfied the no boundary condition. This says that in the imaginary time direction, space-time is finite in extent, but doesn't have any boundary or edge. The predictions of the no boundary proposal seem to agree with observation. The no boundary hypothesis also predicts that the universe will eventually collapse again. However, the contracting phase, will not have the opposite arrow of time, to the expanding phase. So we will keep on getting older, and we won't return to our youth. Because time is not going to go backwards, I think I better stop now."

 

[Milton Platt]

The subjects other than religious or spiritual that interest me most concern 'time' and the nature of the universe. So last night just as I was falling to sleep I asked myself is entropy a requirement for time to exist, or would time exist without entropy, and if it did how could we measure it, or prove it existed? There are examples in nature that indicate when entropy is non existent time does not exist, or slows to the point that it seems not to exist. Best example; The event horizon of a black hole. To observers who exist in the entropy ridden universe that are watching a space ship cross the event horizon of a black hole, the space ship would seem to take eternity to cross it, frozen forever just before entering it. However to the astronauts aboard the ship, time would seem to progress at the normal rate as they passed through the event horizon and into the singularity. So I think I know the answer but I will save it until I hear from our scientific minded members, well if comment! Thanks for your eyeballs and use of your brain!

Actually, could entropy exist without time???

 

[Revoltingest]

Stephan Hawking the beginning of our universe and the beginning of time.

From: The Beginning of TIme

"At this time, the Big Bang, all the matter in the universe, would have been on top of itself. The density would have been infinite. It would have been what is called, a singularity. At a singularity, all the laws of physics would have broken down. This means that the state of the universe, after the Big Bang, will not depend on anything that may have happened before, because the deterministic laws that govern the universe will break down in the Big Bang. The universe will evolve from the Big Bang, completely independently of what it was like before. Even the amount of matter in the universe, can be different to what it was before the Big Bang, as the Law of Conservation of Matter, will break down at the Big Bang.

Since events before the Big Bang have no observational consequences, one may as well cut them out of the theory, and say that time began at the Big Bang. Events before the Big Bang, are simply not defined, because there's no way one could measure what happened at them. This kind of beginning to the universe, and of time itself, is very different to the beginnings that had been considered earlier. These had to be imposed on the universe by some external agency. There is no dynamical reason why the motion of bodies in the solar system can not be extrapolated back in time, far beyond four thousand and four BC, the date for the creation of the universe, according to the book of Genesis. Thus it would require the direct intervention of God, if the universe began at that date. By contrast, the Big Bang is a beginning that is required by the dynamical laws that govern the universe. It is therefore intrinsic to the universe, and is not imposed on it from outside.

The conclusion of this lecture is that the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago. The beginning of real time, would have been a singularity, at which the laws of physics would have broken down. Nevertheless, the way the universe began would have been determined by the laws of physics, if the universe satisfied the no boundary condition. This says that in the imaginary time direction, space-time is finite in extent, but doesn't have any boundary or edge. The predictions of the no boundary proposal seem to agree with observation. The no boundary hypothesis also predicts that the universe will eventually collapse again. However, the contracting phase, will not have the opposite arrow of time, to the expanding phase. So we will keep on getting older, and we won't return to our youth. Because time is not going to go backwards, I think I better stop now."

Stevies one smart fellow, but he wasn't there either.
So his opinion, while better than mine, is still just speculation.

 

[shunyadragon]

Stevies one smart fellow, but he wasn't there either.
So his opinion, while better than mine, is still just speculation.

Actually, it is based on good sound science, and other scientists as well beginning with Einstein's Theory of Relativity. More to follow . . .

It is most definitely above your pay grade.

 

[shunyadragon]

Actually, could entropy exist without time???

No.

 

[Revoltingest]

Actually, it is based on good sound science, and other scientists as well beginning with Einstein's Theory of Relativity. More to follow . . .

It is most definitely above your pay grade.

Do you think those scientists would say there's no chance they're wrong?