Quantum Arrow of Time Solution

[Fra]

I just skimmed the first page and I think the core issues here is the same as the various interpretations of probability.

As we know, entropy is a constructed (unique or not) measure of missing information, or alternatively a kind of measure of the probability of a macrostate given incomplete knowledge about the microstates, or a measure of the complexion number. If we take the subjective probability view here, then clearly also this entorpy measure is subjective (or observer relative), and thus there is a contradiction in imagining.

A frequent observation of entropy decreasing processes would be as to say that we frequently observer improbable events. Well, if we do repeatadly observer so called "improbable" events, then clearly the prior is revised and at some point it is not improbable anymore.

Anyway this all fits well, within a evolutionary view. If the observers are the ones that ENCODE the entropy measures, there should be an evolutionary selection in favour of "constructive codes". A encoding system that consistentely chooses to encode and retain only the most improbable events, would be extremely unfit/non-constructive and would not be very ubiquitous.

I think what he says that "physics cannot study those processes where entropy has decreased" is sensible if we interpret is as

"it's improbable that physical observers has evolved and persisted, that encodes it's own environment as improbable"

If anyone thinks this looks circular, then the circling, is the progress of evolution - there isn't necessarily a beginning and an end to everything. The physical basis of the measure "improbably past" as seen by any observer, simply doesn't exists in the actual past, since the observer itself is a result of evolution itself. So there is no need to pick infinitely unlikely initial conditions, since the complexion number itself, is reduced to triviality in the past, along with the observers.

/Fredrik

 

[Dmitry67]

Exactly! This is also the basis of this comment:
http://xxx.lanl.gov/abs/0912.1947

No, if 'forward flow' is dominating then 'backward observers' are not stable or not formed at all.

 

[Fra]

About the human brain, there are some brain research indicating that the brain is evolved in order to "predict the future", and NOT in order to "remember the past". Clearly there is a difference in survival values between these to traits. An biological organism that in absurdum try to say rememeber only hte most recent past like a "recording device" would be easily put out of competition.

The brain "forgets" or even "modifies" part of the "actual time history", for the benefit of the "expected future". Remembering certain things, has a survival value, and since the brain is limited, remembering everything is not an option. This is why expectations of the future, can distort human memories of the atcual past.

But if entire community or physical environment works like this, there is no objection notion of the "actual past", and at some point it does not matter.

/Fredrik

 

[Demystifier]

No, if 'forward flow' is dominating then 'backward observers' are not stable or not formed at all.

You are missing the point. The paper by Maccone attempts to explain WHY "forward flow is dominating", or more generally, WHY one direction has a different role than the other one. Not to say what are the consequences IF it does, but to explain WHY it does so in the first place.

The Maccone paper fails to do what it attempts to do because it uses a circular argument; it "explains" the time arrow from an assumption that a time arrow already exists.

 

[ThomasT]

The paper seems to me to be an unnecessarily circuitous way of answering the question of why we observe an arrow of time. I agree with those who think that a new, fundamental law of motion is needed. That is, insofar as the current laws of physics are time-symmetric, then they're not describing the fundamental motion.

So, what might be a plausible candidate for such a fundamental law?

It seems to me that an expanding spherical wave shell is worth considering -- and preferable to the current ambiguities of 2nd LoT interpretations.

So, in this view, the radiative arrow of time is the fundamental arrow of time. Disturbances propagate away from their sources. In an ideal, absolutely contiguous, homogeneous medium, the propagation from a point source is isotropic, describing a perfect sphere and the rate and extent expansion is proportional to the energy imparted at the origin of the disturbance. Energy disperses, and dissipates.

Such a fundamental law of motion (the basic wave mechanic) is easy to illustrate in everyday circumstances. Drop a pebble into a smooth pool of water. As the surface wave expands more or less unidirectionally, the energy imparted by the pebble disperses along the wave front and dissipates (the amplitude of the surface wave steadily decreases).

Of course, if such a fundamental law of motion is postulated, then the question of why all waves in all media conform, more or less, to this general dynamic is obviated -- and the arrow of time (and I think maybe some other puzzling foundational issues as well), on any and all scales, is simply and physically accounted for in a readily understandable way.