Is Arrow of Time Reversable?

[Sunstone]

The only asymmetrical law of science dealing with the flow and direction of time is the Second Law of Thermodynamics. It is the Second Law -- and only the Second Law -- that determines the direction time must flow in. That is, from past to future.


I would submit for your consideration the following argument, which I myself neither agree with nor disagree with....

1) The Second Law is empirical.

2) All empirical truth-claims encounter the problem of induction.

3) Hence, it cannot be said with certainty that the Second Law is inviolate.

4) But if it cannot be said that the Second Law is inviolate, then it is possible (albeit demonstrably unlikely) that the Second Law can be reversed.

6) Consequently, it is possible that the arrow of time can be reversed. That is, it is possible to travel back in time.

What makest thou of it?



BONUS QUESTION: Correctly guess the number of households that @Polymath257 's brain can simultaneously power if his brain was wired into an electric grid.

Hint: Scientific notation may be required to answer this question without exceeding the character limit for a post.

 

[Polymath257]

Well, you are incorrect that it is *only* the second law that is temporally asymmetrical. It turns out that the weak nuclear force is also. Furthermore, the weak force is one of the (presumed) fundamental forces and so this is a more fundamental thing than the second law.

The problem with the weak force is, well, that it is weak. It shows up in some types of radioactive decay, is of very short reach, and doesn't seem to otherwise be relevant to, say, the direction of time in the second law. So this time direction *seems* to not be necessarily the one we are interested in.

It is useful, perhaps, to realize that the second law is a *statistical* law. In a sense, it only applies to 'large' collections. We have actually seen violations of it in small samples (involving a dozen or fewer molecules).

Another aspect of this is that the second law can be restated as 'the direction of the arrow of time is that of higher probability'.

For example, if you have a roomful of air, it is incredibly unlikely that all of the molecules will be on one side of the room and none on the other. it is much more likely that about the same number of molecules will be on one side as the other. Hence, the direction of increased probability is to have the air expand from half the room into the rest of the room. That is the direction of entropy increase.

Now, a reasonable question is why the arrow of probability increase should be the same at all locations. Why is it that the direction of time *here* is the same as the direction of time *there*?

And, as I noted above, we can find *small* areas where the direction of entropy increase *is* opposite that of the larger universe. But why the overwhelmingly dominant direction is consistent is a mystery as far as I can see.

 

[Sunstone]

Well, you are incorrect that it is *only* the second law that is temporally asymmetrical. It turns out that the weak nuclear force is also. Furthermore, the weak force is one of the (presumed) fundamental forces and so this is a more fundamental thing than the second law.

The problem with the weak force is, well, that it is weak. It shows up in some types of radioactive decay, is of very short reach, and doesn't seem to otherwise be relevant to, say, the direction of time in the second law. So this time direction *seems* to not be necessarily the one we are interested in.

It is useful, perhaps, to realize that the second law is a *statistical* law. In a sense, it only applies to 'large' collections. We have actually seen violations of it in small samples (involving a dozen or fewer molecules).

Another aspect of this is that the second law can be restated as 'the direction of the arrow of time is that of higher probability'.

For example, if you have a roomful of air, it is incredibly unlikely that all of the molecules will be on one side of the room and none on the other. it is much more likely that about the same number of molecules will be on one side as the other. Hence, the direction of increased probability is to have the air expand from half the room into the rest of the room. That is the direction of entropy increase.

Now, a reasonable question is why the arrow of probability increase should be the same at all locations. Why is it that the direction of time *here* is the same as the direction of time *there*.

And, as I noted above, we can find *small* areas where the direction of entropy increase *is* opposite that of the larger universe. But why the overwhelmingly dominant direction is consistent is a mystery as far as I can see.

I am profoundly grateful for the corrections and new information you have provided me with, Poly. Bless you!

 

[Salvador]

The only asymmetrical law of science dealing with the flow and direction of time is the Second Law of Thermodynamics. It is the Second Law -- and only the Second Law -- that determines the direction time must flow in. That is, from past to future.


I would submit for your consideration the following argument, which I myself neither agree with nor disagree with....

1) The Second Law is empirical.

2) All empirical truth-claims encounter the problem of induction.

3) Hence, it cannot be said with certainty that the Second Law is inviolate.

4) But if it cannot be said that the Second Law is inviolate, then it is possible (albeit demonstrably unlikely) that the Second Law can be reversed.

6) Consequently, it is possible that the arrow of time can be reversed. That is, it is possible to travel back in time.

What makest thou of it?



BONUS QUESTION: Correctly guess the number of households that @Polymath257 's brain can simultaneously power if his brain was wired into an electric grid.

Hint: Scientific notation may be required to answer this question without exceeding the character limit for a post.

Physicists prove time travel possible by sending particles of light into the past

OK...the scientists didn't actually send photons into the past, but they simulated sending a photon into the past where the photon passes through a wormhole and then interacts with its older self.

Experimental simulation of closed timelike curves

• Martin Ringbauer
• , Matthew A. Broome
• , Casey R. Myers
• , Andrew G. White
• & Timothy C. Ralph

Nature Communications volume5, Article number: 4145 (2014)

Experimental simulation of closed timelike curves

 

[ChristineM]

There was this one time

https://phys.org/news/2019-03-physicists-reverse-quantum.html

Followed a day earlier (oops later) by this

No, scientists didn’t just “reverse time” with a quantum computer

 

[Salvador]

Scientists have entangled particles in such a way that a future decision can affect the past states of the particle.

Scientists have entangles particles after they've been measured and may no longer even exist..

Experimental delayed-choice entanglement swapping


Article | Published: 22 April 2012

Experimental delayed-choice entanglement swapping

• Xiao-song Ma
• , Stefan Zotter
• , Johannes Kofler
• , Rupert Ursin
• , Thomas Jennewein
• , Časlav Brukner
• & Anton Zeilinger

Nature Physics volume8, pages479–484 (2012)

https://arxiv.org/ftp/arxiv/papers/1203/1203.4834.pdf

 

[Darkforbid]

No

 

[Polymath257]

No

Well, that is pretty definitive. Why do you think that?

 

[Salvador]

No

Warped space-time with great energy creating tunnels through space-time, if traversable, would allow a traveler to quickly move through great distances in space as well as travel through time.

 

[Salvador]

No

Please let us consider the possibility of backwards time travel in accordance with the hypothetical universe described by a Gödel metric led famed logician Kurt Gödel asserting time might itself be a sort of illusion; time may just be another dimension like space, with all events at all times being fixed within this 4-dimensional "block".

Yourgrau, Palle (4 March 2009). A World Without Time: The Forgotten Legacy of Godel and Einstein. New York: Basic Books. p. 134. ISBN 9780786737000. Retrieved December 18, 2017.

The Novikov self-consistency principle expresses how backwards time travel would be possible without the generation of paradoxes such as the Grandfather paradox.

Backwards time travel creates a casual loop, lacking of any grandfather paradox.

 

[sealchan]

Well, you are incorrect that it is *only* the second law that is temporally asymmetrical. It turns out that the weak nuclear force is also. Furthermore, the weak force is one of the (presumed) fundamental forces and so this is a more fundamental thing than the second law.

The problem with the weak force is, well, that it is weak. It shows up in some types of radioactive decay, is of very short reach, and doesn't seem to otherwise be relevant to, say, the direction of time in the second law. So this time direction *seems* to not be necessarily the one we are interested in.

It is useful, perhaps, to realize that the second law is a *statistical* law. In a sense, it only applies to 'large' collections. We have actually seen violations of it in small samples (involving a dozen or fewer molecules).

Another aspect of this is that the second law can be restated as 'the direction of the arrow of time is that of higher probability'.

For example, if you have a roomful of air, it is incredibly unlikely that all of the molecules will be on one side of the room and none on the other. it is much more likely that about the same number of molecules will be on one side as the other. Hence, the direction of increased probability is to have the air expand from half the room into the rest of the room. That is the direction of entropy increase.

Now, a reasonable question is why the arrow of probability increase should be the same at all locations. Why is it that the direction of time *here* is the same as the direction of time *there*?

And, as I noted above, we can find *small* areas where the direction of entropy increase *is* opposite that of the larger universe. But why the overwhelmingly dominant direction is consistent is a mystery as far as I can see.

Can we analogize that the arrow of time is like the flow of water in a river...under certain circumstances the river's channel can cause small areas where the water moves in the opposite direction as the majority of the water in the river. Then if we think about the orderly arrangement of gas molecules there might be small and temporary eddys in the distribution of gas molecules that move them in the opposite direction.

This seems to be a property of any system that involves a large number of interacting parts which cause positional changes through mutual interaction AND are susceptible to a common interaction/influence which causes them to "flow".

In the case of gases, then, is the flow a result of time itself as a common influence or simply is time a common sense abstraction, an entirely psychological phenomenon, which "explains" various systemic "flows" being predictably in a particular direction or orientation?

I suspect that time is very much an unavoidable "brain distortion" of a reality that is not fundamentally ordered by time as a unique fundamental feature of the universe but is rather an abstract idea in the human brain that lies deep in the patterns that the brain finds and abstracts through language in the universe it finds itself in.

 

[Salvador]

Scientists Claim They Made Time Go Backwards...But Did They?

 

[Brickjectivity]

The only asymmetrical law of science dealing with the flow and direction of time is the Second Law of Thermodynamics. It is the Second Law -- and only the Second Law -- that determines the direction time must flow in. That is, from past to future.


I would submit for your consideration the following argument, which I myself neither agree with nor disagree with....

1) The Second Law is empirical.

2) All empirical truth-claims encounter the problem of induction.

3) Hence, it cannot be said with certainty that the Second Law is inviolate.

4) But if it cannot be said that the Second Law is inviolate, then it is possible (albeit demonstrably unlikely) that the Second Law can be reversed.

6) Consequently, it is possible that the arrow of time can be reversed. That is, it is possible to travel back in time.

What makest thou of it?



BONUS QUESTION: Correctly guess the number of households that @Polymath257 's brain can simultaneously power if his brain was wired into an electric grid.

Hint: Scientific notation may be required to answer this question without exceeding the character limit for a post.

Its a fun question. Quantum effects show that particles exist in multiple states until they collapse, and that collapse is considered to be random. To go backwards you'd perhaps need particles to regain the uncertainty. What would that imply? The particles would first of all cease interacting with other particles. They would 'Untangle'. The forces on and against them would reverse. Gravity would reverse, the strong force would reverse and so forth. Charge would reverse. This change could not be driven by energy, because energy is a result of the way things function not the cause of it. Energy would increase, and entropy would decrease. If you managed to get all of this to happen you'd have an effective freeze effect that would suck energy out of things. You could then create machines with greater than 100% efficiency. It might be dangerous though, because you might not be able to isolate the effect. It might spread throughout the universe. What sort of barrier could stop a time reversal?

 

[columbus]

6) Consequently, it is possible that the arrow of time can be reversed. That is, it is possible to travel back in time.

Sorry dude.
The deadline for your book is still the same place in space and time that it always has been, since the Singularity.
Tom

 

[PureX]

No. But maybe it's possible to 'escape' the timeline, somehow, and re-enter it at some other point.

 

[Sunstone]

It is useful, perhaps, to realize that the second law is a *statistical* law.

Poly, please forgive me for asking a dumb question, but could you confirm or disconfirm my impression that the Second Law is subject to the problem of induction?

 

[Sunstone]

I suspect that time is very much an unavoidable "brain distortion" of a reality that is not fundamentally ordered by time as a unique fundamental feature of the universe but is rather an abstract idea in the human brain that lies deep in the patterns that the brain finds and abstracts through language in the universe it finds itself in.

That's fascinating Sealchan! Could you elaborate on your reasoning for seeing time as a "brain distortion" or perhaps "cognitive bias"? I would enjoy learning as much as I can about this.

 

[Polymath257]

Poly, please forgive me for asking a dumb question, but could you confirm or disconfirm my impression that the Second Law is subject to the problem of induction?

Of course it is. ALL physical laws are ultimately subject to that problem.

 

[ADigitalArtist]

Everyone has already made all the intelligable replies, so I'm just left with this:

 

[Thief]

What makest thou of it?

Albert did say.....time is an illusion
I agree

motion is real enough and has a direction
forward

if history is accessed it is by means of which time equations are not used

it's a matter of thought
and will