Temporal symmetry solves all quantum paradoxes?

[Careful]

I think it does, but I cannot explain it simply, and I don't have time to explain it in detail.

In relation to this, you might find this
http://lanl.arxiv.org/abs/gr-qc/0403001v2
interesting.

Sure not, because there is probably little to explain. Just give me a good common sense argument against my simple examples of Vodka and cerebrial bleeding and then I might look into it.

 

[Careful]

General covariance is very important in my dictionary:
http://xxx.lanl.gov/find/gr-qc/1/AND+au:+Nikolic_H+ti+AND+general+covariant/0/1/0/all/0/1

See also
http://xxx.lanl.gov/abs/gr-qc/0403121

Good, so I was not wrong in that respect then in getting to know each other thoughts on a better level So, then you also understand my joke and difficult challenge to give meaning to your words.

 

[Demystifier]

Just give me a good common sense argument against my simple examples of Vodka and cerebrial bleeding and then I might look into it.

Well, Vodka and cerebral bleeding also increase entropy in the brain, and certainly don't help to remember the future. So I don't see how this example contradicts my claims. To be clear, my claim is that thermodynamic time arrow is necessary, not sufficient, for remembering the past.

 

[Careful]

Well, Vodka and cerebral bleeding also increase entropy in the brain, and certainly don't help to remember the future. So I don't see how this example contradicts my claims. To be clear, my claim is that thermodynamic time arrow is necessary, not sufficient, for remembering the past.

That's not fair, you know I wasn't talking about decrease of entropy, I was talking about decrease of information. Now, I can actually learn many new things, so in general my information will go up (and entropy will go down). A refrigerator does the same thing, so if you want to take it backwards in this way, well yes here you have it. The same thing happens when a single egg cell fertilized by a spermatozoid grows to a full blown baby, information goes up and entropy goes down.

If you deny this, then you get in conflict with Darwinian evolution and precisely confirm what creationists hold against the second law of thermodynamics. Namely that God would be needed to create complex life forms.

 

[Demystifier]

That's not fair, you know I wasn't talking about increase of entropy, I was talking about decrease of information.

So we were not talking about the same thing, so we could not have been in conflict ...

 

[Careful]

So we were not talking about the same thing, so we could not have been in conflict ...

I corrected that sentence meanwhile. Small logical error by typing too fast. So I refer you back to post 54.

 

[Demystifier]

OK, here is a simple explanation of the fact that thermodynamic time arrow explains why do we remember the past and not the future.

The fact is that we actually don't remember anything. All we do is that we observe the state NOW. But from this state now, we try to CONCLUDE something about the future and about the past. Or more precisely, to CORRELATE the state now with the possible future and past states. However, owing to the second law, the correlations diminish towards the future. Thus, it is much easier to make the conclusions about the past. And it is such conclusions about the past that we call "remembering".

 

[Careful]

OK, here is a simple explanation of the fact that thermodynamic time arrow explains why do we remember the past and not the future.

The fact is that we actually don't remember anything. All we do is that we observe the state NOW. But from this state now, we try to CONCLUDE something about the future and about the past. Or more precisely, to CORRELATE the state now with the possible future and past states. However, owing to the second law, the correlations diminish towards the future. Thus, it is much easier to make the conclusions about the past. And it is such conclusions about the past that we call "remembering".

Well, but you really did not answer my objection since the second law does not always hold locally. I agree that what we know about the past is the ''information'' given to us by a measurement *NOW* of our brain state, but what I don't see is what the second law of thermodynamics has to do with this. For example, my guess is that those parts of our brain which deal with the long term memory are quasi stationary with respect to the full *local* hamiltonian of the brain... this would shield them against decay. There is no need to invoque any assymetry in the physics here. The short term memory on the other hand is much more turbulent and mixing of ''information'' can occur here. Of course, it remains to be seen what happens to some long term ''information'' when short term ''information'' becomes long term. But I genuinly think the brain is adaptive here and has the capacity for local entropy decrease.

How would you explain otherwise Darwinian evolution?

 

[Demystifier]

the second law does not always hold.

It holds ALMOST always, provided that you formulate it in a correct way: The system evolves from a less probable state towards a more probable state. (Note that I didn't mention entropy here.)

 

[Careful]

It holds ALMOST always, provided that you formulate it in a correct way: The system evolves from a less probable state towards a more probable state. (Note that I didn't mention entropy here.)

? But there is no such thing as a probability measure on the set of states! Suppose you had one, ok, then it must be invariant under the Poincare group right? So, it seems there does not exist such measure because the latter is not compact (and the ordinary Lebesgue measure does not exist). Again, you would get into severe troubles with Darwinian evolution where everyone intuitively knows that a higher life form is far less probable than a lower one. The only ''dynamical'' ''measure'' we are aware of is some fu***ng renormalized expression
e^{- a H}/ Tr e^{- aH} but yeah that one usually does not exist for interacting theories as far as I remember (and this is certainly not an integration measure over the unit sphere in Hilbert space). Moreover, the standard von Neumann entropy of a usual state is still zero.

You keep on reasoning from the classical perspective, but refuse to answer my very legitimate quantum objections. Not only are my classical objections very much to the point, the burden on you just increases in the quantum world. You would have to go over to these dynamical entropies I explained to you previously and that would get you into severe trouble with general covariance. Moreover, still then you would have to prove (!) that a localized second law holds.

Just out of curiosity, you admitted that sometimes localized entropy goes down. Would you say then that in that case we would turn around future and past ? :-)

 

[Careful]

I agree with you that Darwinian evolution appears to go slow but it really does not in my opinion. If you have children, you would notice for example that the average IQ per generation goes up : our brain functions just become more sophisticated with time (on average). The average length, age and so also increases and it is doubtful that this is merely due to an improvement of nutrition, a better lifestyle or more advanced medicine.

But more to the point is -like I said before- the birth of life, the formation of a child out of a spermatozoid and egg: I think you can hardly claim that a reasonable definition of information would lead to a more or less permanent decrease. That is, it would lead to a logical contradiction, since it would imply that a mother and father contain much more information than their offspring (irrespective of how many children they have) since the latter are only build from a few eggs and spermatozoids (then I don't count the number of times yet that you ''miss'' ). You might think that there is a logical loophole here and that is that somehow, the information of the father -say- would be approximately equal to the information contained in one spermatozoid, but still then information would need to increase once the spermatozoid left the father. I mean, it would be good for my spermatozoids :-)

It seems I am not the only one thinking that, but it is funny to see that a countryfellow of mine initiated the idea http://www.eoht.info/page/Local+entropy+decrease .

 

[Maui]

Just out of curiosity, you admitted that sometimes localized entropy goes down. Would you say then that in that case we would turn around future and past ? :-)

Ouch!

Reductio ad absurdum.

 

[Careful]

Ouch!

Reductio ad absurdum.

Let's try to stay serious here, plenty of respectable people have similar ''ideas'' to those of demystifier, so I appreciate it that we could make the logical excercise .

 

[Maui]

Let's try to stay serious here, plenty of respectable people have similar ''ideas'' to those of demystifier, so I appreciate it that we could make the logical excercise .

The argument ends in a reductio ad absurdum. That was a cool idea on your part.

 

[Careful]

The argument ends in a reductio ad absurdum. That was a cool idea on your part.

Well, if people do not want to listen to more reasonable arguments, you have to pull out the ultimate weapon

 

[nismaratwork]

Well, if people do not want to listen to more reasonable arguments, you have to pull out the ultimate weapon

It's not a weapon, it's a white flag.

 

[Careful]

It's not a weapon, it's a white flag.

English is not my natural language, but if you are suggesting here that this is not a legitimate reductio ad absurdum, then I don't know what does classify in your book like that. Perhaps you might want to comment on the specific arguments I have raised against demystifiers position (and there were plenty of them) instead of uttering a sentence which can just mean anything. I remember having invited you for a specific, technical discussion about the holographic principle. Up till now, I haven't seen any evidence that you do more than just repeating politically correct (but wrong) statements in physics (neither have shown yet to have any particular deep insights into this issue).

Actually, if demystifier feels he can reasonably surpass my objections, I would more than welcome his contributions. But until now, he has offered no evidence that he can (and that might even be an understatement). I am not insisting upon discussing the paper demystifier mentioned, arXiv:1011.4173v1, I just think that the authors are barking up the wrong three (and if someone cares, I could explain that in more detail, but I have no strong desire to do so).

 

[nismaratwork]

English is not my natural language, but if you are suggesting here that this is not a legitimate reductio ad absurdum, then I don't know what does classify in your book like that. Perhaps you might want to comment on the specific arguments I have raised against demystifiers position (and there were plenty of them) instead of uttering a sentence which can just mean anything. I remember having invited you for a specific, technical discussion about the holographic principle. Up till now, I haven't seen any evidence that you do more than just repeating politically correct (but wrong) statements in physics (neither have shown yet to have any particular deep insights into this issue).

Actually, if demystifier feels he can reasonably surpass my objections, I would more than welcome his contributions. But until now, he has offered no evidence that he can (and that might even be an understatement). I am not insisting upon discussing the paper demystifier mentioned, arXiv:1011.4173v1, I just think that the authors are barking up the wrong three (and if someone cares, I could explain that in more detail, but I have no strong desire to do so).

Flying a white flag is one of the universal symbols of surrender... does that clarify my original post?

 

[Careful]

Flying a white flag is one of the universal symbols of surrender... does that clarify my original post?

No, because you seem to imply that I surrender. Or you suggest that he made that error on purpose which I would find quite unlikely. I mean, he cites papers of a single author who has written about this issue, so I assume this author would have an answer to the simple objections I raise. I just glanced into this paper and looked for the argument why interacting systems with a different thermodynamic arrow of time shoud allign their time directions... hmmm the physical idea behind it is not quite ok, I would say, although the math looks superficially ok.

 

[ThomasT]

But if our common sense experience of the world is time asymmetric (I know we remember the past and wonder about the future) in the way we perceive causality, what sense does it make to talk about an objective reality where time is symmetric?

None, imho. I don't know of any compelling reason to think that the time asymmetry of our experience is not rooted in the fundamental dynamics of our universe, and in quantum level phenomena that aren't amenable to our sensory perception.

However, time asymmetry is a somewhat easy solution to some foundational problems. So, some philosopers and physicists adopt this approach.

The truth is, currently, anybody's guess. But it's good to keep in mind that the basic equations of motion of physics aren't correctly identified as time symmetric. Rather, they're time independent. They're equations of 'motion', not of 'time'. And insofar as they might describe a real 'time evolution', then that evolution proceeds in a particular 'direction' and is time asymmetric.

Everything that's actually known about the evolution of our universe suggests that its evolution is asymmetric (which would necessarily apply to the evolution of any of our universe's subsystems).

 

[Careful]

None, imho. I don't know of any compelling reason to think that the time asymmetry of our experience is not rooted in the fundamental dynamics of our universe, and in quantum level phenomena that aren't amenable to our sensory perception.

However, time asymmetry is a somewhat easy solution to some foundational problems. So, some philosopers and physicists adopt this approach.

The truth is, currently, anybody's guess. But it's good to keep in mind that the basic equations of motion of physics aren't correctly identified as time symmetric. Rather, they're time independent. They're equations of 'motion', not of 'time'. And insofar as they might describe a real 'time evolution', then that evolution proceeds in a particular 'direction' and is time asymmetric.

Everything that's actually known about the evolution of our universe suggests that its evolution is asymmetric (which would necessarily apply to the evolution of any of our universe's subsystems).

This might sound weird to you and I am not going to explain myself any further, but my guess is that microscopic physics is fundamentally time symmetric, but macroscopic physics might be *fundamentally* time assymetric. So, as I said, I am not going to explain the mechanism I have in mind to cause such a ''phase'' transition.

 

[ThomasT]

This might sound weird to you and I am not going to explain myself any further, but my guess is that microscopic physics is fundamentally time symmetric, but macroscopic physics might be *fundamentally* time assymetric. So, as I said, I am not going to explain the mechanism I have in mind to cause such a ''phase'' transition.

Intriguing.

 

[ThomasT]

...my guess is that microscopic physics is fundamentally time symmetric ...

And, my guess is that it isn't. I start by assuming that there's a fundamental (wave evolution) dynamic. Sort of a cellular automata approach except that there are no 'cells' to begin with. Just a seamless, homogenous, isotropic medium with some 'disturbances' introduced. There are no original organizational or survival rules other than the fundamental wave dynamic. Some interesting 'creatures' have emerged, as have some higher order organizing principles, or dynamics.

Anyway, good luck with your approach. As far as anybody knows, it might well be the right one.

 

[Careful]

And, my guess is that it isn't. I start by assuming that there's a fundamental (wave evolution) dynamic. Sort of a cellular automata approach except that there are no 'cells' to begin with. Just a seamless, homogenous, isotropic medium with some 'disturbances' introduced. There are no original organizational or survival rules other than the fundamental wave dynamic. Some interesting 'creatures' have emerged, as have some higher order organizing principles, or dynamics.

Anyway, good luck with your approach. As far as anybody knows, it might well be the right one.

Are you then not getting into trouble with relativity? Moreover, one would expect generically to get out the wrong S-matrix since many amplitudes of different scattering processes are connected by time symmetry. How do you explain that? The point of my line of thought is that it is consistent with observations, yours *might* get into trouble fairly quickly.

 

[ThomasT]

Are you then not getting into trouble with relativity?

It's just a fundamental wave dynamic allowed to iterate in a medium. The principles (and constraints) of relativity don't really apply. There are no internal observers. It's a 'birds eye' view. Propagational speed is limited by the computer's processing power.

Moreover, one would expect generically to get out the wrong S-matrix since many amplitudes of different scattering processes are connected by time symmetry. How do you explain that?

S-matrix doesn't apply.

The point of my line of thought is that it is consistent with observations, yours *might* get into trouble fairly quickly.

Well, so are my fundamental conceptual assumptions "consistent with observations", but so far all I can say is that I still don't know if it's a good approach to understanding our universe, nature, reality.

 

[Careful]

It's just a fundamental wave dynamic allowed to iterate in a medium. The principles (and constraints) of relativity don't really apply. There are no internal observers. It's a 'birds eye' view. Propagational speed is limited by the computer's processing power.

S-matrix doesn't apply.

Well, so far I can say that I still don't understand our universe, nature, reality.

? What do you mean by the principles of relativity don't really apply?? They are the most sacred principles of modern physics. Well, it might be that your theory does not contain an S matrix at the fundamental level, that's perfectly ok (I would say it is even good), but still you would need to retrieve the standard S-matrix to a good approximation. THAT's what I was asking for.

 

[ThomasT]

? What do you mean by the principles of relativity don't really apply??

No internal observers. No relativity principles necessary.

They are the most sacred principles of modern physics.

Yes, because modern physics is conducted by internal observers.

... but still you would need to retrieve the standard S-matrix to a good approximation.

It isn't an exercise in constructing a physically viable mathematical theory. It's an exercise in understanding what sorts of particulate regimes, persistent bounded wave structures, etc. might emerge from a single fundamental wave dynamic.

 

[ThomasT]

Back to the OP's question. Yes, temporal symmetry solves lots of problems. Is it the truth? Is it the best approach? I don't think so. But, at this point it's really just a matter of taste, isn't it?

 

[Careful]

Back to the OP's question. Yes, temporal symmetry solves lots of problems. Is it the truth? Is it the best approach? I don't think so. But, at this point it's really just a matter of taste, isn't it?

No I don't agree, there is experimental support for the idea from elementary particle physics (at those scales!). There are however, contra-indications coming from macro-physics (whether, it is a fundamental issue or not at *those* scales, I would say, might a matter of taste so far).

 

[ThomasT]

No I don't agree, there is experimental support for the idea from elementary particle physics (at those scales!).

For what idea? That the experimental evolutions are time-symmetric, or that some aspect of the formalism describing the experiments is invariant wrt time reversal?

There are however, contra-indications coming from macro-physics (whether, it is a fundamental issue or not at *those* scales, I would say, might a matter of taste so far).

Contra-indications to what coming from macrophysics? The time-asymmetry of macrophysical phenomena?

 

[ThomasT]

The point of my line of thought is that it is consistent with observations.

I was thinking about this statement some more. Actually I don't think that it is consistent with observations. As far as I know, all 'observations' indicate time asymmetry. But I'm quite open to being corrected on this.

 

[Careful]

For what idea? That the experimental evolutions are time-symmetric, or that some aspect of the formalism describing the experiments is invariant wrt time reversal?

Contra-indications to what coming from macrophysics? The time-asymmetry of macrophysical phenomena?

Ok, at this point we should say *exactly* what we mean; people mean usually several things with time-reversal invariance. What I mean (and that is the only sensible point of view) is that time-reversal invariance simply means you are working with a Hamiltonian system where H does not explicitely depend upon time. You might work with an explicit time dependent H or like Prigogine did generalize away to nonholonomic mechanics (there exists no energy whatsoever). It seems that both these options have to satisfy severe constraints in order to agree with experiment (which does not mean that I think they are wrong). Another thing people might mean is that you work with a conventional time independent Hamiltonian and then, we know that the CPT theorem has to hold to high accuracy (because gravity is weak). In this framework, the anti-unitary T operator is known not to be an exact symmetry but it is only known to be violated very weakly in the weak interactions. So, again, you would face severe difficulties here if you do not start from a Lagrangian framework in which the T violating terms come with small couplings.

Cheers,

Careful

 

[Careful]

I was thinking about this statement some more. Actually I don't think that it is consistent with observations. As far as I know, all 'observations' indicate time asymmetry. But I'm quite open to being corrected on this.

Again, it depends upon what you mean with this (let's clarify it first ok?). When I say that microphysics is to a good degree time symmetric, then I intend to say that the conventional time independent Hamiltonian picture with it's CPT invariance works rather well. For macrophysics, I would agree that it doesn't and what I have in mind approaches better the first two options I mentioned (so the time dependent Hamiltonian and/or Prigogine scheme).

Careful

 

[ThomasT]

Again, it depends upon what you mean with this (let's clarify it first ok?). When I say that microphysics is to a good degree time symmetric, then I intend to say that the conventional time independent Hamiltonian picture with it's CPT invariance works rather well.

Ok, this makes sense to me. The problem is that it isn't really an indication (at least certainly not a definitive one) that (sub)microphysical phenomena are time-symmetric.

You seem to be looking for a formalism that works ok, whereas my interest is in understanding the (apparent) time-asymmetric evolution of our universe (and its subsystems).

For macrophysics, I would agree that it doesn't and what I have in mind approaches better the first two options I mentioned (so the time dependent Hamiltonian and/or Prigogine scheme). Careful

So, I'm wondering, why not apply this approach to (sub)microscopic systems as well?

 

[Careful]

You seem to be looking for a formalism that works ok, whereas my interest is in understanding the (apparent) time-asymmetric evolution of our universe (and its subsystems).

You should not mix two things here: if you would stick to conventional physics as we know it today, then the only explanation for localized entropy increases/decreases I can cook up is by looking at the initial values. People seem to agree that those would have to be rather special to give our macroscopic universe and I agree with amongst others Bob Wald that it is rather pointless to look for dynamical theories which would explain those. So, there really is at the moment no hint for a better explanation and we seem to get lost in anthropic reasoning. On the other hand, if some fundamental assymetry would creep in on the *macroscopic* scale, we have a much better chance at getting there.

So, I'm wondering, why not apply this approach to (sub)microscopic systems as well?

Because it would violate Lorentz invariance. Nobody says that Lorentz invariance has to hold for large objects, because then gravity is dominant and it brakes global Lorentz invariance brutally. However, for tiny things like electrons or photons Lorentz invariance holds to a much higher degree and *might* only get violated at energy scales close to the Planck energy.
That's why.

Cheers,

Careful

 

[ThomasT]

You should not mix two things here: if you would stick to conventional physics as we know it today, then the only explanation for localized entropy increases/decreases I can cook up is by looking at the initial values.

Values are unimportant wrt fundamental dynamics. Values are emergent. Values will be more or less unpredictable.

Suppose you come up with a TOE based on your approach. Will you be able to predict anything with it? Probably not. Neither will I with my approach. But which one will lead to a better understanding of nature, of the evolution of our universe?

I'll reply to the rest of your statements in about 30 minutes as I have to run an errand.

 

[ThomasT]

People seem to agree that those would have to be rather special to give our macroscopic universe ...

I agree with this. But those 'values' didn't come from nothing, and our universe is 'evolving'.

... and I agree with amongst others Bob Wald that it is rather pointless to look for dynamical theories which would explain those.

I agree that an understanding wrt a fundamental dynamic(s) will probably not account for specific observed values as currently formulated. And who is Bob Wald?

So, there really is at the moment no hint for a better explanation and we seem to get lost in anthropic reasoning.

I would tend to agree with this also. But looking for an understanding via a fundamental dynamic(s) is about as far from anthropic reasoning we can get. Don't you think?

On the other hand, if some fundamental assymetry would creep in on the *macroscopic* scale, we have a much better chance at getting there.

Sure. That's another reason to look for it, or assume it, at the (sub)microscopic scale.

Because it would violate Lorentz invariance. Nobody says that Lorentz invariance has to hold for large objects, because then gravity is dominant and it brakes global Lorentz invariance brutally. However, for tiny things like electrons or photons Lorentz invariance holds to a much higher degree and *might* only get violated at energy scales close to the Planck energy.

Well, yes. If the aim is to explain certain values, then that will require a value-laden approach. However, if the aim is to 'understand' the emergence of complex, time-asymmetric, evolving systems in general, then a time-asymmetric fundamental (wave?) dynamic(s) would seem to be the approach to take, imho.

 

[ThomasT]

By the way, I'm researching Bob Wald now.

 

[ThomasT]

OK, that, Bob Wald. His stuff is over my head. Probably your stuff (that you are reluctant to reveal) is over my head too. No problem. I've enjoyed our conversation. Anything further that you might want to enlighten me wrt is appreciated. Thanks.

 

[Careful]

OK, that, Bob Wald. His stuff is over my head. Probably your stuff (that you are reluctant to reveal) is over my head too. No problem. I've enjoyed our conversation. Anything further that you might want to enlighten me wrt is appreciated. Thanks.

This is a good stopping point

 

[Careful]

However, if the aim is to 'understand' the emergence of complex, time-asymmetric, evolving systems in general, then a time-asymmetric fundamental (wave?) dynamic(s) would seem to be the approach to take, imho.

I know why you believe this conclusion is ''unavoidable'' if you insist upon a fundamental time assymetric dynamics at the macroscopic scale. But it really isn't: that is all I have to say.