arrow of time

[Gary Oberbrunner]

"Time’s Arrow Traced to Quantum Source"

https://www.simonsfoundation.org/quanta/20140416-times-arrow-traced-to-quantum-source/

--
Gary

[Allen Francom]

thx - well written

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[Bruno Marchal]

Hi Allen, hi Gary,

On 17 Apr 2014, at 16:53, Allen Francom wrote:

thx - well written

On Thu, Apr 17, 2014 at 7:47 AM, Gary Oberbrunner <ga...@oberbrunner.com> wrote:

"Time’s Arrow Traced to Quantum Source"

https://www.simonsfoundation.org/quanta/20140416-times-arrow-traced-to-quantum-source/

--

Here is a reply I did to a remark by Richard Ruquist. You might be interested, and I think it generalizes Allen's idea to define space from time.

BTW, I apology as I have begun a thread, here, on the math used to extract physics from arithmetic "in the self-referential way", but it seems to have continued on the everything list (in between I moved and my mailing abilities were hostages of the electrical companies, for 1.5 month!). Sorry for possible inconvenience.

===================================================

On 17 Apr 2014, at 13:14, Richard Ruquist wrote:

Classical thermodynamics and heat transfer calculates the approach to equilibrium exactly AFAIK. Increasing the amount/range of statistics which I expect entanglement should do should then increase the rate of approach to equilibrium which apparently it does not, otherwise there would be empirical data to support the entanglement story, which apparently there is not. So I suggest that entanglement is just an alternative or more detailed explanation of classical thermodynamics.

The links is interesting. 

Actually I agree with you Richard, classical thermodynamic explains completely and exactly the heat transfer.

But of course there is a catch: the "world" seems to not be classical, and somehow, the quantum by itself put the classical explanation in doubt. That is a subtle point and to be honest I am not at ease here. For years I disbelieved (wrongly) in the possibility of quantum chaos. But I knew some physicists seemed worrying finding a quantum version of the thermodynamical classical explanation in the quantum frame. Comp leads to a sequence of similar problems.

Now the entanglement role in explaining the equilibrium exactly seems rather obvious to me, and I am not that astonished by the article and Lloyd's contribution. It seems to me it that this is just equivalent with the idea of avoiding collapse, which spreads the superposition quickly and "vastly" (by simple combinatorial use + the usual lienarities of QM), so that this is probably just the "classical" thermodynamical explanation in the MW context. (Which might not be your favorite reason why we agree on this!). Such an explanation of time might survived in the marriage between QM and GR. 

(And QM itself must be given by a first person plural equilibrium of that sort, at a relatively deeper level, if we take comp seriously enough).

When Lloyd says: "“The present can be defined by the process of becoming correlated with our surroundings.”", it is basically the indexical definition of time, and you can relate it to Everett relative state, and to the relative computational state in arithmetic. I think it is hardly avoidable in monist philosophies where there is ONE simple thing or principle, and the MANY is given by the internal views of that simple thing seen from inside. Lloyd, like everybody (except in this list), does not push that kind of logic as far as computationalism needs us to do.

Bruno

====

Gary

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http://iridia.ulb.ac.be/~marchal/

[Allen Francom]

Hi All,

We should wait for Stephen a little bit.  He is amassing some ammo.  Meanwhile, Miroljub makes the case 

that quantum mechanically, equilibrium is only ever "approached", never quite achieved.  i.e., some process

keeps on processing...  This relates to a number of other things I don't really want to open the can of worms

on at the moment but it does all go together and indeed very much in terms of "what is space anyway",

thought this may not be exactly fitting.  

( I think it sort of does, due to the required "decoherence time", if there is such, and Entanglement Relativity )

The "negligible" decoherence time, I see as necessarily repeating and thus not quite "negligible" or 

rather "not irrelevant" in some as yet to be elucidated case... say for example, this is so many 

seconds away from that, and that ... is indistinguishable from 'space', and right here is the 

machanical process that makes it so.  ( classical material has 'position'.  quantum material

has 'probability' of position "" )  Quickly enough repeated probability would enact a 

'relatively consistent position'.  How quickly ?   Sky is the limit at the moment because

( prove otherwise )

Here is one from Stephen regarding the instantaneous issue from slightly earlier today:

  A neat paper that I found while looking at the article that Allen posted:

http://math.rutgers.edu/~oldstein/papers/TypicalDecayLett03.pdf

Extremely quick thermalization in a macroscopic quantum system for a typical

nonequilibrium subspace

Sheldon Goldstein1

, Takashi Hara2

, and Hal Tasaki3

1Departments of Mathematics and Physics, Rutgers University,

110 Frelinghuysen Road, Piscataway, NJ 08854-8019, USA

2Faculty of Mathematics, Kyushu University, Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan

3Department of Physics, Gakushuin University, Mejiro, Toshima-ku, Tokyo 171-8588, Japan

(Dated: February 3, 2014)

The fact that macroscopic systems approach thermal equilibrium may seem puzzling, for example,

because it may seem to conflict with the time-reversibility of the microscopic dynamics. We here

prove that in a macroscopic quantum system for a typical choice of “nonequilibrium subspace”, any

initial state indeed thermalizes, and in fact does so very quickly, on the order of the Boltzmann time

τB := h/(kBT). Therefore what needs to be explained is, not that macroscopic systems approach

equilibrium, but that they do so slowly.

***

I should mention that papers like this tend to assume that the system does not have any structure that can change the rate of the thermalization effects.

[John Clark]

On Thu, Apr 17, 2014 at 12:36 PM, Bruno Marchal <mar...@ulb.ac.be> wrote:

> Actually I agree with you Richard, classical thermodynamic explains completely and exactly the heat transfer.

Yes but that's not sufficient to explain the Arrow Of Time. The laws of classical physics can explain how one particle in a system moving in a straight line much faster than average can transition into a system of lots of particles moving in lots of different directions that are moving only very slightly faster than they were before. And it can explain how even though the second system has as much energy as the first less work can be extracted from it because work is a force applied in a specific direction not in lots of different directions. And because there are more ways to be disordered than ordered the laws of classical physics can explain why Entropy will be greater tomorrow than it is today.

But it can not explain why Entropy was less yesterday than today, after all if there are far more disordered states than ordered ones the probability is overwhelming that the previous state of universe was one of those states. The only way out of this mess is to remember that the laws of physics are not all you need to know, you also need to know the initial conditions, you need to  assume that everything started out in a very low entropy state.

> But of course there is a catch: the "world" seems to not be classical

I'm not sure that's relevant.  It seems to me that by the mid 19th century physicists had everything they needed to have deduced that the Big Bang must have occurred, but unfortunately they did not.

  John K Clark

 

[Allen Francom]

A few thoughts for food while waiting:

>"“The present can be defined by the process of becoming correlated with our surroundings.”"

If the daisy-chain of information is broken then there is MWI and no explanation for "now" and "correlating" to begin with.

( remember Miroljub and Jasmina's POD+ER attack on Everett MWI - now in Springer )

That is to say, there is something about this "connective tissue" that is persistent even if everything is random chaos it is still "this universe".

The requirement of information (all) to be relative (connected) makes a universal "now".  And this is completely inescapable. (imnsho)

(Independent Reference Frame) is phoey in an absolute sense, thereby.

"Spacetime" is not Space And Time.  It is "spacetime" a whole new word.  A wholeness.

Remember Einstein himself was personally transitioning from Space and Time to "Spacetime" and thus had a remaining issue with "spooky action at a distance" and 'dice play'.

On Thu, Apr 17, 2014 at 11:36 AM, Bruno Marchal <mar...@ulb.ac.be> wrote:

[LizR]

I gave my views in a comment on the article's web site, but briefly, istm that saying time's arrow derives from the spreading of entanglement is no better than saying it derives from the increase of entropy. Assuming time symmetry of physics, as I believe QM does, these are both emergent phenomena and need to be explained via boundary conditions on the system in question (i.e. the universe). You can't derive asymmetry from symmetry unless the system is forced to make some arbitrary choice to reach minimum energy, but there is no indication I can see that symmetry splitting is involved.

[Bruno Marchal]

On 17 Apr 2014, at 23:50, LizR wrote:

I gave my views in a comment on the article's web site, but briefly, istm that saying time's arrow derives from the spreading of entanglement is no better than saying it derives from the increase of entropy. Assuming time symmetry of physics, as I believe QM does, these are both emergent phenomena and need to be explained via boundary conditions on the system in question (i.e. the universe). You can't derive asymmetry from symmetry unless the system is forced to make some arbitrary choice to reach minimum energy, but there is no indication I can see that symmetry splitting is involved.

I am not sure I understand your point. You can derive asymmetry from symmetry in the MW, or in the WM-duplication. Of course we keep the 3p symmetry, but the appearance of asymmetry seems to me completely explained by self-multiplication. There is local creation of information, despite information remains constant in the big 3p picture. May be I missed your argument.

Bruno

http://iridia.ulb.ac.be/~marchal/

[Bruno Marchal]

On 17 Apr 2014, at 19:29, Allen Francom wrote:

A few thoughts for food while waiting:

>"“The present can be defined by the process of becoming correlated with our surroundings.”"

If the daisy-chain of information is broken then there is MWI and no explanation for "now" and "correlating" to begin with.

( remember Miroljub and Jasmina's POD+ER attack on Everett MWI - now in Springer )

I don't see what is missing in the indexical explanation of the now and here.

That is to say, there is something about this "connective tissue" that is persistent even if everything is random chaos it is still "this universe".

It is still this appearance of a universe, like in the WM-duplication. 

The requirement of information (all) to be relative (connected) makes a universal "now".  And this is completely inescapable. (imnsho)

The global information is not temporal at all, it is not a now, it is just out of the time category, like the fact that 15 is smaller than 17.

(Independent Reference Frame) is phoey in an absolute sense, thereby.

I agree. That's why the big things is not a physical reference frame. But it can still be a simple mathematical reality (like arithmetical truth), from which all the dependent reference frames becomes accessible from the creature inside.

"Spacetime" is not Space And Time.  It is "spacetime" a whole new word.  A wholeness.

Remember Einstein himself was personally transitioning from Space and Time to "Spacetime" and thus had a remaining issue with "spooky action at a distance" and 'dice play'.

Which is reasonable enough with QM, but are explained, it seems to me, by Everett and/or computationalism.

Bruno

http://iridia.ulb.ac.be/~marchal/

[LizR]

On 18 April 2014 19:01, Bruno Marchal <mar...@ulb.ac.be> wrote:

On 17 Apr 2014, at 23:50, LizR wrote:

I gave my views in a comment on the article's web site, but briefly, istm that saying time's arrow derives from the spreading of entanglement is no better than saying it derives from the increase of entropy. Assuming time symmetry of physics, as I believe QM does, these are both emergent phenomena and need to be explained via boundary conditions on the system in question (i.e. the universe). You can't derive asymmetry from symmetry unless the system is forced to make some arbitrary choice to reach minimum energy, but there is no indication I can see that symmetry splitting is involved.

I am not sure I understand your point. You can derive asymmetry from symmetry in the MW, or in the WM-duplication. Of course we keep the 3p symmetry, but the appearance of asymmetry seems to me completely explained by self-multiplication. There is local creation of information, despite information remains constant in the big 3p picture. May be I missed your argument.

I'm not sure I understand you argument. How do you derive asymmetry from symmetry in the MW? (Bearing in mind that worlds can combine in the MW, and would do so as much as they split at equilibrium.)

I'll come back to the WM once I understand the MW case.

[Gary Oberbrunner]

On Fri, Apr 18, 2014 at 3:01 AM, Bruno Marchal <mar...@ulb.ac.be> wrote:

On 17 Apr 2014, at 23:50, LizR wrote:

I gave my views in a comment on the article's web site, but briefly, istm that saying time's arrow derives from the spreading of entanglement is no better than saying it derives from the increase of entropy. Assuming time symmetry of physics, as I believe QM does, these are both emergent phenomena and need to be explained via boundary conditions on the system in question (i.e. the universe). You can't derive asymmetry from symmetry unless the system is forced to make some arbitrary choice to reach minimum energy, but there is no indication I can see that symmetry splitting is involved.

I am not sure I understand your point. You can derive asymmetry from symmetry in the MW, or in the WM-duplication. Of course we keep the 3p symmetry, but the appearance of asymmetry seems to me completely explained by self-multiplication. There is local creation of information, despite information remains constant in the big 3p picture. May be I missed your argument.

 

Saying that duplication machines exist, but merging machines (2->1) don't, begs the question I think.  If you run the film backwards you get self-merging instead of self-multiplication. Each of you can predict that you will be the sole survivor of the merge, and you will both be correct (as your histories will of necessity converge).  Of course there is still the statistical-likelihood argument, but that's just the classical-physics number-of-available-states argument.  (Which I already think is compelling, but that's a different story.)

--
Gary

[Bill Taylor]

On Friday, April 18, 2014 5:29:07 AM UTC+12, John K Clark wrote:

But it can not explain why Entropy was less yesterday than today, after all if there are far more disordered states than ordered ones the probability is overwhelming that the previous state of universe was one of those states. The only way out of this mess is to remember that the laws of physics are not all you need to know, you also need to know the initial conditions, you need to  assume that everything started out in a very low entropy state.

Yes of course; but as I've noted before, this hardly counts as a true *explanation*
of the Arrow of Time.  It is at best, the "formal cause" of the AoT, whereas
an "explanation" would include the (more explicative) "efficient cause".
i.e. Just how does it GET from state(t) to state(t+dt).

As noted earlier, claiming the AoT is explained by the fact that the system
started with very low entropy, is like asking "why does a rock roll down a hill"
and giving the answer as: "because it started at the top"!

Surely the analogy here is very tight, and obvious?  OC the explanation
given is a sine qua non of the effect to be explained, but equally surely
is it not avoiding at least half of the issue?  In the case of the rock,
we not only would be happy to know it started at the top, but we'd
also like to know about gravity, the topography, initial instability
and perturbations (quakes and storms), local basins of stability
and so on.  Only then would we *fully* understand what "makes"
the rock fall down the hill.

In the case of the AoT, where is this secondary but perhaps more vital
information?  It is to some extent involved with standard astrophysics,
nuclear resonances, internal gravity and so forth, but as I've noted
before, the *chief mechanism* for *driving* the AoT, is the widespread
effect of "radiative reduction".  That is, whenever there's a bang of
any kind, much of the effect *radiates away* and reduces in effects
by the inverse square law.  The effects of almost any change in
the universe, radiate spherically outward, AND THESE EFFECTS
DO NOT REVERSE, by the simple abstract formal nature of radiation.

There are countless irreversible processes in the universe:-
radiation emitting from stars, from particle movements in
galactic or local magnetic fields, from decay, accident, friction,
and rocks falling down hills.
(And OC rock strata being slowly forced UP again, at the expense
of the earth's interior energy, the decay of U_235.)   And if one
analyses closer and closer into these processes, one will find that
they ALL involve radiating away energy (or information) from
a central point in a spherical shell pattern.  And to set up
a pattern that *radiates inward* so as to (locally, briefly)
result in a reversal of the AoT is so fantastically, wildly
improbable that in effect, it never happens.   Unless, OC, some
intelligent being, running a diabolically cunning experiment,
manages to do so, with enormous squandering of resources.

This efficient cause of the AoT seems so blindingly obvious to me,
that I am baffled as to why people have such a hard time cottoning
onto it.  Now it may be, OC, that the quoted paper's account
of entanglement of equipment and environment can also be
seen in this way.  Personally I'm dubious - AFAICS it's
actually the opposite that does it, i.e. decoherence rather
than entanglement.   But perhaps these are just 2 sides of
the same coin, though it seems to me that the paper's authors
have actually got the wrong end of the stick somehow.

But then, what do I know? - a simple mathematician.

Bright-beamed Bill

Q:  Why are speedy stars often ejected from galaxies?
A:  Because they started inside them!

Q2:  Why did the chicken cross the road?
A2:      <this is your test question!>

[Gary Oberbrunner]

On Fri, Apr 18, 2014 at 9:05 AM, Bill Taylor <shirt...@hotmail.com> wrote:

And to set up
a pattern that *radiates inward* so as to (locally, briefly)
result in a reversal of the AoT is so fantastically, wildly
improbable that in effect, it never happens. 

This is the core of it.  It's the number-of-available-states argument in another guise.  Spherical radiation is only one aspect; so's photon emission in random directions and at random times, and so on.  No matter what the starting state, there are more less-ordered states accessible from that state than more-ordered states, so most state transitions from any given state will be toward less-ordered states.

And yes, the paper approaches it from the co-entanglement perspective, but it's the same thing as decoherence.  (Once the experimenter's entangled with the cat, the whole system is in a superposition, which is another way of saying it's decohered into multiple worlds.  Both of them are really just ways of rejecting collapse without saying that explicitly; saying "superposition" just allows them to not come down squarely on the MWI side and muddy their argument IMHO.  It's still the number-of-available-states argument AFAICT, though they seem to have some kind of new theoretical underpinning, which I don't completely understand yet.

--
Gary

[Allen Francom]

Well, here is a thought...

If you run QM "backwards" you still have to operate uncertainty principle.  So QM'ically, you get entropy no matter "what direction of time" you try to "move" in.

Therefore, QM-time, is necessarily "forward only" no matter what you do.

;)

[Allen Francom]

>>"“The present can be defined by the process of becoming correlated with our surroundings.”"
>>If the daisy-chain of information is broken then there is MWI and no explanation for "now" and >>"correlating" to begin with.
>>( remember Miroljub and Jasmina's POD+ER attack on Everett MWI - now in Springer )

>I don't see what is missing in the indexical explanation of the now and here.

I'm saying something to emphasise "no branching" and completed
daisy-chain of hand-shakes throughout. ( this also makes for first
principle of ability for 'collision detection' to work ala "same time,
same place". there is not an fully independent time, or "local now"
other-wise it would be out of phase with somebody else and "ghostly"
and no collision detection - ever )

I have yet to convince M and J of the striking resemblance of Everett
MWI to spatial space "operating by way of the same assumed magic" but
I'm getting closer... To my reasoning, the end of the branching is
the same as the end of the spatial space. Leaving only temporal
interaction for all effects to ride upon "appear in", etc.,

[Bruno Marchal]

Lol!

Normally Washington/Moscow WM-duplication is simpler than the quantum mechanical many worlds MW, but they are close, especially if, like Quentin and I guess others, I thought that was clear for you, you relate the first person indeterminacy and the quantum self-entanglement:

me x (cat-dead + cat-alive) = (me x cat-dead + me x cat-alive) , which evolves by the SWE into 

(me-seeing-the-cat-dead x cat-dead + me-seeing the cat-alive x cat-alive).  "x" is the tensor product.

Abstracting from the many states of the particles around me in the cat, which multiplies the possibilities, that case can be seen as a self-duplication of the WM type. The situation is 3p symmetrical and reversible, in both the classical self-duplication and the quantum self-superposition. In the 3p view, no bit of information has been created, nor destroyed. But in the 1p of the experiencers (me looking at the cat), both get one bit of information, they know and can verify by repetitive measurement that the cat is dead, relatively to him, or alive, relatively to the second him. 

For a precise account of time, we might need to solve the marriage GR+QM, but it seems to me that to explain the phenomenological quantum entropic decoherence (the "arrow of time"?), such entanglement provides it by the general big number combinatorial laws.

The measure problem in comp (but also in QM+GR) is the information inflation that such theories are facing.

Bruno

[Bruno Marchal]

On 18 Apr 2014, at 15:05, Bill Taylor wrote:

This efficient cause of the AoT seems so blindingly obvious to me,
that I am baffled as to why people have such a hard time cottoning
onto it.  Now it may be, OC, that the quoted paper's account
of entanglement of equipment and environment can also be
seen in this way.  Personally I'm dubious - AFAICS it's
actually the opposite that does it, i.e. decoherence rather
than entanglement.   But perhaps these are just 2 sides of
the same coin, though it seems to me that the paper's authors
have actually got the wrong end of the stick somehow.

OK. 

Note that decoherence is the first person view of a self-entanglement with some particles or environment, in the "MWI" (QM without collapse).

Bruno

http://iridia.ulb.ac.be/~marchal/

[LizR]

On 18 Apr 2014, at 15:05, Bill Taylor wrote:

This efficient cause of the AoT seems so blindingly obvious to me,
that I am baffled as to why people have such a hard time cottoning
onto it.  Now it may be, OC, that the quoted paper's account
of entanglement of equipment and environment can also be
seen in this way.  Personally I'm dubious - AFAICS it's
actually the opposite that does it, i.e. decoherence rather
than entanglement.   But perhaps these are just 2 sides of
the same coin, though it seems to me that the paper's authors
have actually got the wrong end of the stick somehow.

The radiation / dissipation / decoherence / entanglement / whatever argument seems blindingly obvious to us because we're so used to living in a world ruled by the second law, but it fails in logical and physical terms unless it addresses what put the universe into this state so everything could run downhill from there. Before I go any further this is based on the assumption, and so far the observation, that the laws of physics are (99.9%) time symmetric. If they aren't, then obviously that gives us an asymmetry that causes the AOT, end of story.

So one needs to know why a situation arose in which radiation etc are more likely in one time direction than the other. Bill's argument is equivalent to the rock starting at the top of a hill UNLESS he explains how the universe comes to be set up that way, and the obvious explanation (blindingly obvious in fact) is the expansion of the universe. Without that everything would be in a state of high temperature (the Planck temperature, in fact) in which all processes would work equally well in either time direction, so no AOT. Or if one magically stopped the expansion at (say) one second after the big bang, the plasmaball would quickly thermalize, and again no AOT. Basically each system we know of that contributes negative entropy to the universe as we now observe it resulted from a time-symmetric process which became "frozen out" at some point in the big bang due to the expansion of the universe.

So...

...given a thermalised quark-gluon plasma that would remain as it was forever unless the universe expanded...

...the expansion cools it, and it turns into nuclei. This is a time-symmetric process ABOVE the temperature at which the nuclei froze out, but the expansion caused the process to become asymmetric as the temperature fell. The same is true of all the succeeding steps, so I won't both to keep repeating it.

Given a thermalised cloud of nuclei and electrons that would remain as it was forever unless the universe expanded some more...

...the expansion cools it, and it turns into atoms.

...Given a thermalised cloud of atoms...

...the expansion cools it, and it (eventually) turns into clumps, which later become stars, galaxies, planets and people. A simple way to visualise this - the big bang fireball was effectively a large star at one point, which eventually split up into lots of smaller stars separated by empty space, the empty space being created by the cosmic expansion.

Each step provides negative entropy, and depends on the expansion of the universe. Hence given time symmetric laws of physics and an expanding universe, we get an entropy gradient. The origin of the AOT is the expansion of the universe, which is the next thing that needs to be explained in the causal (or ontological) chain.

Any explanation which just states "it's obvious that entropy works this-a-way because that's how it appear to us" - or variants involving dissipation, radiation, entanglement, decoherence or invisible pink unicorns - is a non-explanation, imho, because it misses how that situation became privileged.

[Russell Standish]

On Sat, Apr 19, 2014 at 10:48:58AM +1200, LizR wrote:
> >
> > The radiation / dissipation / decoherence / entanglement / whatever
> argument seems blindingly obvious to us because we're so used to living in
> a world ruled by the second law, but it fails in logical and physical terms

> *unless* it addresses what put the universe into this state so everything

It seems obvious to me that the combination of anthropic principle,
occam's razor and evolution gives us the explanation that the
beginning must have been simple, and evolved to the current complex
state required for the AP via the expansion of state space and the
operation of the second law.

What other reasoning gives a priveleged situation at the beginning of
time?

It also neatly retrodicts the expansion of the universe...

Cheers

--

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[LizR]

This is true, and it is an alternative approach. But if one is sticking purely with the physics / materialist camp, then the AoT emerges naturally from the expansion of the universe, and radiative dissipation, our sense of time flowing, etc are a consequence, not a cause of the AoT. (And the original thermalized quark-gluon plasma arises naturally from eternal inflation, as far as I can tell from Max Tegmark's latest book.)

Deducing the AoT from comp/ToN* etc is an alternative which I wasn't trying to address. My post was purely in the physical / materialist camp, since it was in reply to a post which was also in that camp.

I will have a look into the comp/ToN approach when I have a bit more time. It seems fairly clear that a UD will generate time indexically, since (istm) more complex states will appear to have arisen from simpler ones. Is that a fair comment? But it's far from clear to me (as yet) that the basic assumptions of comp are correct (specifically "yes doctor" ... or that humans having beliefs is equivalent to a formal system in which one can show something like []p & p, with apologies to Bruno if I got that wrong off the top of my head).

This is not to say that I believe comp/ToN to be wrong, I just haven't got my head around it/them enough to have a definite opinion (beyond "they seem fascinating and worth further effort"). Whereas the physical emergence of the AoT from the cosmic expansion seems "blindingly obvious".

-- Laser-eyed Liz

*didn't he discover X-rays or something?

[John Clark]

On Fri, Apr 18, 2014 at 9:05 AM, Bill Taylor <shirt...@hotmail.com> wrote:

> As noted earlier, claiming the AoT is explained by the fact that the system started with very low entropy, is like asking "why does a rock roll down a hill" and giving the answer as: "because it started at the top"!

Yes and that is an excellent answer. But why the exclamation point?  

> Surely the analogy here is very tight, and obvious? 

Yes it is obvious and a first rate analogy. Understanding how the laws of gravity operate is necessary but not sufficient to explain why the rock moved as it did, no matter how profound your understanding of the laws of physics you can't explain anything unless you also know the initial conditions, in this case that the rock started out at the top of the hill.  

 

> as I've noted before, the *chief mechanism* for *driving* the AoT, is the widespread effect of "radiative reduction".  That is, whenever there's a bang of
any kind, much of the effect *radiates away* and reduces in effects by the inverse square law.  The effects of almost any change in
the universe, radiate spherically outward, AND THESE EFFECTS DO NOT REVERSE,

That is incorrect. The fundamental laws of physics could be reversed and everything would still be perfectly logical provided that EVERYTHING is reversed, including the physical processes going on on the observers brain.  Consider a red hot iron ball the size of a golf ball at the center of a cold iron shell the size of a basketball, as a forward thinking physicist who remembers the past you know that a spherical stream of photons will leave the hot iron golf ball and hit the cold iron basketball, and so as time progress the golf ball will become significantly colder and the basketball will become slightly warmer, and although the total energy will be the same it will become increasingly difficult to extract work out of the system, and this is perfectly consistent with the well known law of physics that says heat always moves from hot to cold or to put it another way entropy always increases.

And this situation is entirely symmetrical, you just have to play fair and reverse everything. As a backward thinking physicist who remembers the future you know that a spherical stream of photons will leave the cold iron golf ball and hit the hot iron basketball, and so as time progress the golf ball will become significantly hotter and the basketball will become slightly colder, and although the total energy will be the same it will become increasingly easier to extract work out of the system and this is perfectly consistent with the well known law of physics that says heat always moves from cold to hot or to put it another way entropy always decreases.

Or consider a different example, open a bottle of perfume and observe how the molecules of the fragrance diffuse until they evenly fill the air of the entire room. But how would things look to you if everything were reversed? For a start you would remember the future but the past you could only conjecture about, so you would remember that in the distant future, that is to say a long way from your "now", perfume molecules "were" evenly distributed throughout the room, and you would remember that in the more recent future the molecules were only in the lower right part of the room, and you would remember that in the even more recent future (very close to your "now") all the molecules were confined inside one small perfume bottle. You would then conclude that entropy always decreases or remains the same. And as to how the bottle of perfume got into that room in the first place.... well, you can make educated guesses but essentially the past is unknowable.

And yet as good as my argument is the fact remains that is NOT how we observe the world,  our brain and thus our minds work in one direction but not in the other, so we never observe entropy decreasing. But why not? If the answer can't be found in the fundamental laws of physics then there is only one other place a explanation for time's asymmetry could be found, the initial conditions.

  John K Clark

[Gary Oberbrunner]

On Sat, Apr 19, 2014 at 12:37 AM, John Clark <johnk...@gmail.com> wrote:

there is only one other place a explanation for time's asymmetry could be found, the initial conditions.

... you mean the final conditions, surely. :-) :-) :-)

(More correctly perhaps, the boundary conditions taken as a whole, both spatial and temporal.)

--
Gary

[John Clark]

On Sat, Apr 19, 2014 at 8:53 AM, Gary Oberbrunner <ga...@oberbrunner.com> wrote:

 

>> there is only one other place a explanation for time's asymmetry could be found, the initial conditions.

> ... you mean the final conditions, surely. :-) :-) :-)

Yes, if you're a reverse thinking physicist. 

> (More correctly perhaps, the boundary conditions taken as a whole, both spatial and temporal.)

I prefer initial conditions because boundary conditions implies that there are two special states at both ends of the timeline that can not be derived from the laws of physics, and as far as we know there is only one.

  John K Clark

 

[Gary Oberbrunner]

On Sat, Apr 19, 2014 at 10:16 AM, John Clark <johnk...@gmail.com> wrote:

On Sat, Apr 19, 2014 at 8:53 AM, Gary Oberbrunner <ga...@oberbrunner.com> wrote:

 

>> there is only one other place a explanation for time's asymmetry could be found, the initial conditions.

> ... you mean the final conditions, surely. :-) :-) :-)

Yes, if you're a reverse thinking physicist. 

Exactly.  Either works in either case, though.  The equations work out the same.

 

> (More correctly perhaps, the boundary conditions taken as a whole, both spatial and temporal.)

I prefer initial conditions because boundary conditions implies that there are two special states at both ends of the timeline that can not be derived from the laws of physics, and as far as we know there is only one.

True, if everything is linear (which it is, as far as we can tell).  If there's any nonlinearity you need more boundary conditions -- either value and derivative at start, or value at start and end (for quadratic) and so on.

 

--
Gary

[LizR]

Did I say initial? I meant boundary, because you need both a big bang and timeline infinity.

--

[Bruno Marchal]

"yes doctor" is a way to express mechanism or computationalism, without committing any ontological commitment. It is just the idea that the brain or the body does not rely on something non Turing emulable, in the matter of preserving my consciousness. 

This entails, for the ideally correct case that we need to derive the physical laws from arithmetic.  That entails that the brain, at the correct substitution level, can be seen as a formal system, like any computer. This gives the box [] for the beliefs (the part which I attempted two times to explain recently), and then the []p & p is Theatetetus' idea, which fits nicely with many data.

If comp is true, we will never know it, although we might find it very plausible, in case we practice it every day, like when going everyday on mars by teleportation. But even that will not constitute a public truth, and a personal experience proves nothing.

Keep in mind that comp is not proposed as a theory to explain things, but as a fertile source of new problems: notably the problem of reducing physics to arithmetic. Comp suggests strongly that the mystics and Platonists might just be less wrong than the Aristotelians, on nature's nature, and in that sense it suggests the shape of the mind-body problem.

Bruno

This is not to say that I believe comp/ToN to be wrong, I just haven't got my head around it/them enough to have a definite opinion (beyond "they seem fascinating and worth further effort"). Whereas the physical emergence of the AoT from the cosmic expansion seems "blindingly obvious".

-- Laser-eyed Liz

*didn't he discover X-rays or something?

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[Bill Taylor]

On Saturday, April 19, 2014 1:25:41 AM UTC+12, Gary O wrote:

This is the core of it.  It's the number-of-available-states argument in another guise.

Hmmm.
 

 Spherical radiation is only one aspect; so's photon emission in random directions and at random times,

Well, those two things are identical in MWI.

| And yes, the paper approaches it from the co-entanglement perspective, but it's the same thing as decoherence.
| (Once the experimenter's entangled with the cat, the whole system is in a superposition,
| which is another way of saying it's decohered into multiple worlds.

Nice way of looking at it; thanks for that.    -- Bouncy Bill

[Bill Taylor]

On Saturday, April 19, 2014 10:48:58 AM UTC+12, Liz R wrote:

The radiation / dissipation / decoherence / entanglement / whatever argument seems blindingly obvious to us because we're so used to living in a world ruled by the second law, but it fails in logical and physical terms unless it addresses what put the universe into this state so everything could run downhill from there.

Well, no-one's going to come out and say "Let there be light!", are they!

| So one needs to know why a situation arose

Even using the word "arose" is kind of prejudging things - "let there be light" is arosement

| Bill's argument is equivalent to the rock starting at the top of a hill

So you're agreeing with me?

| UNLESS he explains how the universe comes to be set up that way,

"To be set up" - very deimorpjic again!

| and the obvious explanation (blindingly obvious in fact) is the expansion of the universe.

This is obvious once we know about expansion, but priorly there are other possible cases.

| Without that everything would be in a state of high temperature (the Planck temperature, in fact)

NOT necessarily, in fact.

| in which all processes would work equally well in either time direction, so no AOT.

That is correct.  But there are ways OTHER than expansion that the gods could have used.
You seem to be *equating* expansion with AOT, but it is not so.
Expansion will imply an AOT, but not vice versa.      <-----[my essential point!!]
It is a sufficient condition but not a necessary one.

| Hence given time symmetric laws of physics and an expanding universe, we get an entropy gradient.

You have still overlooked the point I am making - the importance also of UNIFORMITY,
i.e. homogeneity in the universe.

| The origin of the AOT is the expansion of the universe,

As it happens; but it didn't NEED to be that way.

| which is the next thing that needs to be explained in the causal (or ontological) chain.

Too simple an approach. 
What needs explanation is, why expansion rather than heterogeneity?
And maybe other possibilities too.

For example:  the universe could have been finite and static,
i.e. non-expanding - say just a 3-D torus where stuff "going out"
one side "comes back in" the other.  BUT, rather than starting out
(effectively) uniform, it could have started out with one half
having high entropy, and the other half having high ordering.
(I hate the word "negentropy"!)   I suspect this option for the universe
would be very appealing to Zoroastrians and diabolists!

Then, for a long time, entropy would be leaking from one side
to the other, running lots of life-enhancing effects while doing so.
The length of the "long time" would depend on the size of
the universe and the difference of entropies between the halves;
just as in our universe it depends on the energy density at some
specified temperature.

So, in summary, the AOT can be "caused" by various things,
expansion is one, non-uniformity is another, perhaps pink unicorns
is yet another - not much work has been done on that yet.

So complaining of "lack of imagination" about a dissipation/hysteresis
explanation of things isn't much of an intellectual mistake, compared
with the lack of imagination about "causes" of the AOT, leading to
implicit identification of AOT with expansion.   Very bad thinking.
And in the meantime, WHATEVER the origin of changing entropy,
(and entropy is OC the *key* discovery here), the METHOD of
entropy lowering, involving all those things I mentioned, that physics
has studied in detail over the centuries, is still crucial.

Just as the study of gravity, topography, hillside gradient and
basins of stability, are crucial to understanding why a rock rolls
down a hill.  Sure it would be nice to know how it got to start
at the top, but we are wondering about it rolling down,   i.e. AOT!

Battering Bill

** I do not expect any backing down, OC, but uncommitted
** 3rd parties might be thought provoked.

[LizR]

On 20 April 2014 21:01, Bruno Marchal <mar...@ulb.ac.be> wrote:

"yes doctor" is a way to express mechanism or computationalism, without committing any ontological commitment. It is just the idea that the brain or the body does not rely on something non Turing emulable, in the matter of preserving my consciousness. 

Yes I know. I just have some trouble getting my head around the idea, and even more all it entails. I do find it a beautiful idea, but it is just a bit mind boggling.

I just finished your book ("The Amoeba's Secret") which I found very interesting, and rather moving in places.

 

This entails, for the ideally correct case that we need to derive the physical laws from arithmetic.  That entails that the brain, at the correct substitution level, can be seen as a formal system, like any computer. This gives the box [] for the beliefs (the part which I attempted two times to explain recently), and then the []p & p is Theatetetus' idea, which fits nicely with many data.

Yes, but the mind-boggling part means that I find it hard to believe that my beliefs, which are often fairly complex and variable, are reducible to "[]p & p". This is probably just me being silly, or perhaps it's a failure of the imagination. (Also it was a day with an R in it.)

If comp is true, we will never know it, although we might find it very plausible, in case we practice it every day, like when going everyday on mars by teleportation. But even that will not constitute a public truth, and a personal experience proves nothing.

Keep in mind that comp is not proposed as a theory to explain things, but as a fertile source of new problems: notably the problem of reducing physics to arithmetic. Comp suggests strongly that the mystics and Platonists might just be less wrong than the Aristotelians, on nature's nature, and in that sense it suggests the shape of the mind-body problem.

Don't get me wrong, I think it's a wonderful theory, even if non explanatory - and insofar as I understand it - but I beg leave to put on a materialist hat when discussing the arrow of time, and to at least pretend they are "non-overlapping magisteria" for the sake of the discussion.

[LizR]

On 20 April 2014 23:55, Bill Taylor <shirt...@hotmail.com> wrote:

Just as the study of gravity, topography, hillside gradient and
basins of stability, are crucial to understanding why a rock rolls
down a hill.  Sure it would be nice to know how it got to start
at the top, but we are wondering about it rolling down,   i.e. AOT!

Well we're talking at cross purposes then, you're interested in the processes that occur due to the AOT and I'm wondering where it originates (ontologically). So more non-overlapping magisteria.

 

[Bill Taylor]

On Saturday, April 19, 2014 4:37:38 PM UTC+12, John K Clark wrote:

> As noted earlier, claiming the AoT is explained by the fact that the system started with very low entropy, is like asking "why does a rock roll down a hill" and giving the answer as: "because it started at the top"!

Yes and that is an excellent answer. But why the exclamation point?  

Because most people would NOT regard that as an "explanation"
of the rock rolling down the hill.  Merely a "pre-condition",
not an explanation.

As usual, our debates reduce to usages of English words, but I think I'm
on the sensible side here - the side the whole world is on, except for
AOT physicists.  As so often, the specialist distorts everyday words
so far from their everyday meanings, that they become lies, in effect,
just to support a particular case.

"Starting at the top" is NOT an explantion of rolling down, it is merely
a pre-condition.  Search your heart, Luke. and you will know it to be true!

 
>> The effects of almost any change in the universe,
>> radiate spherically outward, AND THESE EFFECTS DO NOT REVERSE,

That is incorrect.

Actually it IS correct, in QM, (though your point holds classically I suppose.)
One could reverse every single photon, graviton, neutrino and particle in
the universe, and it would NOT run back up to the Big Bang (now Crunch).
The uncertainty principle stops it!  Everywhere and everywhen, 2-particle
interactions would have slightly different outcomes, or actually "incomes".
So in the large, everything would mostly go in film-reverse for a little while,
but the one-way entropic local effects would revert to low-to-high entropy
very soon, and things would still continue to decay as before.

I doubt if even a pebble could be ripple-shot out of a pool, if the pool
were big enough!  Entropy would soon sludge the effect out.

-- Tendentious Taylor

Q:  Why did the chicken cross the road?
A:  Because it started on this side!

 

[Bill Taylor]

On Monday, April 21, 2014 12:11:28 AM UTC+12, Liz R wrote:

On 20 April 2014 23:55, Bill Taylor <shirt...@hotmail.com> wrote:

 

Just as the study of gravity, topography, hillside gradient and
basins of stability, are crucial to understanding why a rock rolls
down a hill.  Sure it would be nice to know how it got to start
at the top, but we are wondering about it rolling down,   i.e. AOT!

Well we're talking at cross purposes then, you're interested in the processes that occur due to the AOT

No, that is NOT so - that's just you grabbing the subject matter by fiat.

MY account, with its stress on friction, dissipation, hysteresis,
and (chiefly) radiation, is (in effect) an account of what entropy IS,
why it works the way it does, and why things go from low to high.
The mere fact that there are more high-entropy states than
low-entropy states, is not in itself a sufficient account.

As I explained (seemingly successfully) to John Clark some while ago,
as well as the number of states of the various kinds, one must also
know about the transition probabilities from state to state -
and that is EXACTLY what my radiation account deals with
(admittedly in a very simple-minded and non-mathematical way).

But YOUR top-of-the-hil account explains NOTHING,.
You don't even know what entropy IS, hardly, until you
understand local and brief micro-changes, the transition
probabilities, which your account is BLIND to.

I am saying what AOT actually "IS" - you're merely observing
that the measurement of it needs to start high because it
always falls, which is hardly a profound observation!

-- Withering Wills

[John Clark]

On Sun, Apr 20, 2014 at 8:14 AM, Bill Taylor <shirt...@hotmail.com> wrote:

>>> As noted earlier, claiming the AoT is explained by the fact that the system started with very low entropy, is like asking "why does a rock roll down a hill" and giving the answer as: "because it started at the top"!

>> Yes and that is an excellent answer. But why the exclamation point?  

> Because most people would NOT regard that as an "explanation"

 

So what? Most people, even most graduates of ivy league liberal arts universities, can't even explain why seasons exist. And it would be silly to say that if you knew what state a system was in today you could predict what it's state would be tomorrow if you didn't know the laws of physics; that would be as silly as saying that if you knew the laws of physics you could predict what state a system would be in tomorrow even if you didn't know what state it was in right now.

> "Starting at the top" is NOT an explantion of rolling down

It's part of an explanation, necessary but not sufficient. And I could say exactly the same thing about the laws of physics.

 > it is merely a pre-condition.

A precondition yes, but what's with the "merely"?

 

>>>The effects of almost any change in the universe, radiate spherically outward, AND THESE EFFECTS DO NOT REVERSE,

>> That is incorrect.

> Actually it IS correct, in QM, (though your point holds classically I suppose.)

Mathematically the Schrodinger Wave Equation works as well in the forward direction as the backward and it is completely deterministic; true that doesn't mean that the actual physical object the wave is associated with is deterministic too because Schrodinger can only provide probabilities not certainties. But Schrodinger is equally fuzzy and probabilistic going in one direction along the timeline as in the opposite direction, it's symmetrical in that regard. So how can it give us a preferred direction, how can it generate the Arrow of Time?
 

> One could reverse every single photon, graviton, neutrino and particle in the universe, and [...]

And then you would have exactly as much difficulty in figuring out the past as we have in figuring out the future. So I ask again how does this produce the Arrow of Time? It can't, so it must come from initial conditions. 

If the laws of physics were the same but the Big Bang was a state on maximum entropy instead of very very low entropy then time would not exist, entropy would not change because it was already as high as it could get. To use your analogy, once the rock you started rolling down the hill reaches the bottom friction will soon bring it to a stop because there is no longer a force being applied to keep it moving. And once everything winds down and reaches a state of maximum entropy it will be the heat death of the universe.

  John K Clark

[Bruno Marchal]

On 20 Apr 2014, at 14:09, LizR wrote:

On 20 April 2014 21:01, Bruno Marchal <mar...@ulb.ac.be> wrote:

"yes doctor" is a way to express mechanism or computationalism, without committing any ontological commitment. It is just the idea that the brain or the body does not rely on something non Turing emulable, in the matter of preserving my consciousness. 

Yes I know. I just have some trouble getting my head around the idea, and even more all it entails. I do find it a beautiful idea, but it is just a bit mind boggling.

I just finished your book ("The Amoeba's Secret") which I found very interesting, and rather moving in places.

Yeah ... I feel a bit sorry for that. Also. But that's life.

 

This entails, for the ideally correct case that we need to derive the physical laws from arithmetic.  That entails that the brain, at the correct substitution level, can be seen as a formal system, like any computer. This gives the box [] for the beliefs (the part which I attempted two times to explain recently), and then the []p & p is Theatetetus' idea, which fits nicely with many data.

Yes, but the mind-boggling part means that I find it hard to believe that my beliefs, which are often fairly complex and variable, are reducible to "[]p & p". This is probably just me being silly, or perhaps it's a failure of the imagination. (Also it was a day with an R in it.)

We humans, are Löbian, as far as we are arithmetically correct, notably when discussing with the surgeon on our third person description, and that is all what we need to derive physics from machine self-reference. it would make not sense to interview an incorrect machine.

But we, as concrete human with a complex life, are almost never correct, and we do have a large supplementary non-monotonic(*) layer, where we *can* revise many beliefs, thanks to God. We are "variable" machines, but still Löbian at our correct level, for the matter of ... living in some plausible material world.

It would be nice to derive that non-monotonic layer from the hypostases, and that might be possible, but this if for the next generations ...

(*) A logic is monotonic if adding an axiom extends only the set of theorems. A logic is non monotonic if the addition of a "axiom" makes an older axiom wrong, forcing you to revise a belief, and lose "theorems". You can still be *locally* Löbian, and that is what count for the physics.

If comp is true, we will never know it, although we might find it very plausible, in case we practice it every day, like when going everyday on mars by teleportation. But even that will not constitute a public truth, and a personal experience proves nothing.

Keep in mind that comp is not proposed as a theory to explain things, but as a fertile source of new problems: notably the problem of reducing physics to arithmetic. Comp suggests strongly that the mystics and Platonists might just be less wrong than the Aristotelians, on nature's nature, and in that sense it suggests the shape of the mind-body problem.

Don't get me wrong, I think it's a wonderful theory, even if non explanatory - and insofar as I understand it - but I beg leave to put on a materialist hat when discussing the arrow of time, and to at least pretend they are "non-overlapping magisteria" for the sake of the discussion.

No problem, I was only oblivious of the spelling of the month :)

Bruno

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[Bill Taylor]

On Monday, April 21, 2014 5:21:31 AM UTC+12, John K Clark wrote:

> "Starting at the top" is NOT an explanation of rolling down

It's part of an explanation, necessary but not sufficient.

I'm glad we agree on this!

 

>>>The effects of almost any change in the universe, radiate spherically outward, AND THESE EFFECTS DO NOT REVERSE,

>> That is incorrect.

> Actually it IS correct, in QM, (though your point holds classically I suppose.)

Mathematically the Schrodinger Wave Equation works as well in the forward direction as the backward and it is completely deterministic; true that doesn't mean that the actual physical object the wave is associated with is deterministic too because Schrodinger can only provide probabilities not certainties.

So again, you agree with me!
 

But Schrodinger is equally fuzzy and probabilistic going in one direction along the timeline as in the opposite direction, it's symmetrical in that regard. So how can it give us a preferred direction, how can it generate the Arrow of Time?

The probabilistic nature of it enforces the direction.
As I said, if one magically reverses all, it would not rewind exactly.

|  If the laws of physics were the same but the Big Bang was a state on maximum entropy instead of very very low entropy then time would not exist,

Well, it would be unmeasurable/undetectable "from outside",
so I guess in a positivistic sense it would "not exist".
But we agree there would be no detectable change.

Thank you for your support.

-- Balancing Bill

**  When blackberries are red they're still green.

[John Clark]

On Sun, Apr 20, 2014 at 9:48 PM, Bill Taylor <shirt...@hotmail.com> wrote:

>>> "Starting at the top" is NOT an explanation of rolling down

>> It's part of an explanation, necessary but not sufficient.

> I'm glad we agree on this!

And do you also agree with me that the laws of physics are necessary but not sufficient to explain why the ball is moving as it is?

>> Mathematically the Schrodinger Wave Equation works as well in the forward direction as the backward and it is completely deterministic; true that doesn't mean that the actual physical object the wave is associated with is deterministic too because Schrodinger can only provide probabilities not certainties.

> So again, you agree with me!

I would prefer to phrase it as you agree with me.

>>  But Schrodinger is equally fuzzy and probabilistic going in one direction along the timeline as in the opposite direction, it's symmetrical in that regard. So how can it give us a preferred direction, how can it generate the Arrow of Time?

> The probabilistic nature of it enforces the direction.

I don't see how.

> As I said, if one magically reverses all, it would not rewind exactly.

It's true that things wouldn't rewind exactly, but things don't wind exactly either; mathematically Schrodinger's Wave Equation makes predictions that are equally fuzzy in both time directions. So how does that produce asymmetry in time or in anything else?

And if you conclude that the entropy tomorrow will almost certainly be larger than what it is today because there are vastly more disordered states than ordered ones then why couldn't you use the exact same logic and conclude that yesterday was almost certainly in one of those far more numerous disordered high entropy states?  Why couldn't you conclude that both tomorrow and yesterday will be (or were) almost certainly in a higher entropy state than today? There is only one reason this conclusion is false, it takes the laws of physics into account but ignores something of equal importance, initial conditions.

  John K Clark

 

|  If the laws of physics were the same but the Big Bang was a state on maximum entropy instead of very very low entropy then time would not exist,

Well, it would be unmeasurable/undetectable "from outside",
so I guess in a positivistic sense it would "not exist".
But we agree there would be no detectable change.

Thank you for your support.

-- Balancing Bill

**  When blackberries are red they're still green.

[LizR]

On 22 April 2014 04:57, John Clark <johnk...@gmail.com> wrote:

And if you conclude that the entropy tomorrow will almost certainly be larger than what it is today because there are vastly more disordered states than ordered ones then why couldn't you use the exact same logic and conclude that yesterday was almost certainly in one of those far more numerous disordered high entropy states?  Why couldn't you conclude that both tomorrow and yesterday will be (or were) almost certainly in a higher entropy state than today? There is only one reason this conclusion is false, it takes the laws of physics into account but ignores something of equal importance, initial conditions.

Exactly what I said.  :-)

You should take into account final conditions as well (i.e. all boundary conditions) because it's possible a Gold universe would include time reversal. Big Bang plus endless expansion appears to be sufficient to create an arrow of time. The various stages of "freezing out negative entropy" from time-symmetric processes in the early big bang are well understood (if not normally phrased in quite that way).

[Kermit Rose]

On 4/21/2014 4:06 PM, LizR wrote:

On 22 April 2014 04:57, John Clark <johnk...@gmail.com> wrote:

And if you conclude that the entropy tomorrow will almost certainly be larger than what it is today because there are vastly more disordered states than ordered ones then why couldn't you use the exact same logic and conclude that yesterday was almost certainly in one of those far more numerous disordered high entropy states?  Why couldn't you conclude that both tomorrow and yesterday will be (or were) almost certainly in a higher entropy state than today? There is only one reason this conclusion is false, it takes the laws of physics into account but ignores something of equal importance, initial conditions.

Huh?????????????????????????????????/  You have completely lost me.


If you can conclude that the entropy tomorrow will almost certainly be larger than what it is today, for what ever reason,
then you can conclude that the entropy today is almost certainly larger than what is was yesterday, which means
that the entropy yesterday is almost certainly smaller than what is is today.


Kermit

[LizR]

Since you have mis-attributed that quote to me, I will attempt to reply.

John is restating Boltzman's argument that if one has time symmetric laws of physics, then without any other conditions being imposed, it is a priori most likely that their time evolution from a low entropy state will be to higher entropy states in both the past and future directions. This is what the 2nd law tells us will happen in the absence of any other constraints (i.e. with no boundary conditions).

This is the same argument that gives us "Boltzman brains" in a sufficiently long lived universe at thermodynamic equilibrium. Boltman used it to attempt to explain the order in the universe, which is where the idea of a Boltzman brain originates (in a universe at thermodynamic equilibrium, it is vastly more likely for a brain - or enough of one - to come into existence long enough to give me this instant of consciousness than it is for, say, the Earth to come into existence, or the observable universe). The fact that this appears paradoxical is a good reason to suspect that there is more to time's arrow than meets the eye, as King Harold might have put it. The "more to it" is either that the laws of physics somehow mandate it in a yet to be discovered manner, or if the laws of physics are time symmetric, that there is some boundary condition(s) which mandate it. I don't know of a third alternative.

Stated otherwise: you can only conclude that entropy will increase in one time direction if it is somehow fixed to be very low at some point in (what seems to us to be) the remote past.

[Bill Taylor]

On Tuesday, April 22, 2014 4:57:41 AM UTC+12, John K Clark wrote:

>>> "Starting at the top" is NOT an explanation of rolling down

>> It's part of an explanation, necessary but not sufficient.

> I'm glad we agree on this!

And do you also agree with me that the laws of physics are necessary but not sufficient to explain why the ball is moving as it is?

 
SOME laws of physics probably are.  But it is quite possible to imagine
other laws of physics that would produce the same gross result.

>>  But Schrodinger is equally fuzzy and probabilistic going in one direction along the timeline as in the opposite direction,

it's symmetrical in that regard. So how can it give us a preferred direction, how can it generate the Arrow of Time?

> The probabilistic nature of it enforces the direction.

I don't see how.

That's what I've been explaining these last few posts, and in an earlier thread.

> As I said, if one magically reverses all, it would not rewind exactly.

Here, OC, I meant "exactly the same in reverse".

> It's true that things wouldn't rewind exactly, but things don't wind exactly either;

They don't wind *predictably*, if that's what you mean. Similarly, they
are not precisely retrodictable, which is what I think you go on to say:-

| mathematically Schrodinger's Wave Equation makes predictions that are equally fuzzy in both time directions.

Not once the probabilistic nature of their predictions is factored in !
The retrodictions and predictions then may be quite different.

> And if you conclude that the entropy tomorrow will almost certainly be larger than what it is today

I do.

> because there are vastly more disordered states than ordered ones

But NOT because of that!  I have addressed this point several times, and you
have failed to acknowledge it, except with an apparent consent by silence.

The NUMBER of disordered states is in itself NO GUARANTEE of their popularity.
Equally vital, in fact more so, are the transition probabilities, as I keep stressing.
These are essential in any stochastic processes.  Crudely speaking, there are
four types:  ord to ord, ord to dis, dis to ord, dis to dis.  That is a vast
oversimplification OC; but you have persitrently and obdurately failed to
recognize that they might even exist!

An even greater oversimplification, is what I have clumsily attempted to
illustrate with my various scenarios of dissipating effects - these are all
crude illustrations of the general effects of these transition probabilities.

-- Tiring T.

**  The math is done right, but is the right math done?

[Gary Oberbrunner]

On Mon, Apr 21, 2014 at 10:41 PM, Bill Taylor <shirt...@hotmail.com> wrote:

The NUMBER of disordered states is in itself NO GUARANTEE of their popularity.
Equally vital, in fact more so, are the transition probabilities,

I think if you count the states properly (applying a measure), the probabilities just fall out.  I.e. it's the same to say that there are two possible outcomes A and B of probabilities 1/4 and 3/4, as to say there are 4 possible outcomes of equal probability, and 3 of them are indistinguishable.  (Or that there are infinitely many, but 1/4 of them are indistinguishable and can be labeled A, and the other 3/4 are indistinguishable and can be labeled B.)

--
Gary

[Kermit Rose]

On 4/21/2014 8:28 PM, LizR wrote:
>
> Stated otherwise: you can only conclude that entropy will increase in
> one time direction if it is somehow fixed to be very low at some point
> in (what seems to us to be) the remote past.
>
>

My focus is as follows:

Since it is undeniable that entropy does increase in only one time
direction,
and we call "future" the time direction in which it increases,
then in the opposite direction, the past,
entropy must decrease.

Of course, a consequence of entropy decreasing in the time direction
past implies that the maximum entropy occurred at
the first moment of time.

If you are saying anything different than this, I am not able to follow you.

Note: This model of time does not preclude that at some distant points
of our space, time is running backward with respect to our time line.

Kermit

[John Clark]

On Mon, Apr 21, 2014 at 4:06 PM, LizR <liz...@gmail.com> wrote:

> You should take into account final conditions as well (i.e. all boundary conditions)

First of all we're not even sure the universe has a final boundary condition, and even if it does as far as we know it could be derived from the laws of physics and knowledge of the state of the universe as it is now; that is not the case at the other end of the timeline.

 

> Big Bang plus endless expansion appears to be sufficient to create an arrow of time.

Yes exactly, the Big Bang, that is to say initial conditions.

  John K Clark

[Allen Francom]

I like these thoughts.

Except, Boltzman would have nailed it before the last thought. Time
is not a dimension, it IS and "arrow", so to speak, no matter "what
direction" you might imagine it is forward only due to Heisenberg has
to be maintained in any such direction. Makes going backward a real
big trick, bordering "impossible". I said 'bordering'...

Meanwhile, entropy seems poorly understood when taken to the extremes
of either black hole or heat death.

In the later case, the ultimate expression of that idea is the failure
to be able to perform a measure of a distance, and bang, no 'size'
property to be made manifest... then what happens... Oh, I said
"bang" already... That's my guess.

--

- - - -
light...@gmail.com

[John Clark]

On Mon, Apr 21, 2014 at 10:41 PM, Bill Taylor <shirt...@hotmail.com> wrote:

>>>>> "Starting at the top" is NOT an explanation of rolling down

>>>>  It's part of an explanation, necessary but not sufficient.

>>>  I'm glad we agree on this!

>> And do you also agree with me that the laws of physics are necessary but not sufficient to explain why the ball is moving as it is?

 
> SOME laws of physics probably are. But it is quite possible to imagine other laws of physics that would produce the same gross result.

Then you're going even further than I am. I'm saying the laws of physics as we know them are necessary but not sufficient to explain why the ball is moving as it is, I'm saying you also need to know the initial conditions; but you're saying the laws of physics are not even necessary.  I think that's going one step too far.

>> mathematically Schrodinger's Wave Equation makes predictions that are equally fuzzy in both time directions.

> Not once the probabilistic nature of their predictions is factored in !

Probability must be factored in regardless of the direction you run Schrodinger's Wave Equation.

> The retrodictions and predictions then may be quite different.

Show me. I want a concrete example of time asymmetry in Schrodinger's Wave Equation.

> And if you conclude that the entropy tomorrow will almost certainly be larger than what it is today

> I do.

I'm glad to hear that.

 

>> because there are vastly more disordered states than ordered ones

> But NOT because of that! 

Why on earth not?! You keep pointing out (correctly) that there is a element of unpredictability or randomness (events without causes) associated with the laws of physics, so if there are vastly more disordered states than ordered ones then if you pick one at random the chances are overwhelming it will be one of those more disordered states. And we have always found that this turns out to be true, tomorrow always has had more entropy than today. . But by using the exact same logic we can conclude that the probability is overwhelming that things were also in one of those more disordered states yesterday. But however good the logic is we have NEVER found that to turn out to be true, yesterday has always had LESS Entropy than today not more as you'd expect. The question is why. The answer is initial conditions. 

> The NUMBER of disordered states is in itself NO GUARANTEE of their popularity.

If I can't convince you perhaps Caltech physicist Sean Carroll can. From http://www.preposterousuniverse.com/eternitytohere/faq.html

"The first mystery of the arrow of time is that it's nowhere to be found in the fundamental laws of physics. Those laws work perfectly well if we run processes backwards in time. [...]  An omelet is higher entropy than an egg because there are more ways to re-arrange its atoms while keeping it indisputably an omelet, than there are for the egg. That provides half of the explanation for the Second Law: entropy tends to increase because there are more ways to be high entropy than low entropy. The other half of the question still remains: why was the entropy ever low in the first place?"

Please note that Carrol is saying just what I've been saying over and over, the laws of physics can explain HALF of the Arrow of Time (why Entropy will be higher tomorrow than today)  but not the other half (why entropy was less yesterday than today).

More from Carroll:

"The observed macroscopic irreversibility is not a consequence of the fundamental laws of physics, it's a consequence of the particular configuration in which the universe finds itself. In particular, the unusual low-entropy conditions in the very early universe, near the Big Bang. Understanding the arrow of time is a matter of understanding the origin of the universe."

Please note that Carrol is saying just what I've been saying over and over, you can't explain the Arrow of Time without considering initial conditions, that is to say the Big Bang.

Carroll has more interesting stuff to say on this subject at:

http://preposterousuniverse.com/talks/time-colloq-07/time-colloq-07.pdf

  John K Clark

[John Clark]

On Mon, Apr 21, 2014 at 7:52 PM, Kermit Rose <ker...@polaris.net> wrote:

> If you can conclude that the entropy tomorrow will almost certainly be larger than what it is today, for what ever reason

The reason you can conclude it is important! There are vastly more high entropy states than low so the chances are overwhelming that the present state of the universe will almost certainly evolve into one of those higher entropy states.

> then you can conclude that the entropy today is almost certainly larger than what is was yesterday,

No.  There are vastly more high entropy states than low so the chances are overwhelming that the present state of the universe was almost certainly evolved from one of those higher entropy states. Except it didn't. Why? Initial conditions.

  John K Clark

[LizR]

On 23 April 2014 01:20, Kermit Rose <ker...@polaris.net> wrote:

On 4/21/2014 8:28 PM, LizR wrote:

Stated otherwise: you can only conclude that entropy will increase in one time direction if it is somehow fixed to be very low at some point in (what seems to us to be) the remote past.

My focus is as follows:

Since it is undeniable that entropy does increase in only one time direction,
and we call "future" the time direction in which it increases,
then in the opposite direction, the past,
entropy must decrease.

Of course, a consequence of entropy decreasing in the time direction past implies that the maximum entropy occurred at
the first moment of time.

If you are saying anything different than this, I am not able to follow you.

That's more or less it, except that it isn't a single point in time at which the entropy is minimal. It's slightly more complex, in that the expansion of the universe raises the entropy ceiling (maximum possible entropy in a given volume) and continues to do so indefinitely, though more and more slowly. (Effectively, more space means more potential states are available for matter to occupy). Hence the universe can come to thermodynamic equilibrium, and may well have done so in the Big Bang, but the expansion means that the entropy ceiling rises and the entropy of the universe, which was briefly maximised, finds itself no longer the maximum possible. The ceiling moves ahead of the thermalisation processes, which keep "trying" to catch up by generating atoms, radiating stars, broken eggs, etc. The AOT is the difference between the entropy ceiling and the actual entropy.

As I mentioned before, there are several physical processes involved that we know about. These cause various bound ("negative entropy") states of matter to emerge from unbound (time-symmetric) states as the universal temperature falls (or equivalently, as the universe gets larger). Hence, for example, quark soup can remain in a state of thermodynamic equilibrium indefinitely if it isn't expanding  / cooling, but itf it is, this reduces the collision energies to a point where bound states (nucleons) form. If you imagine nuclei falling into a big crunch the reverse would happen: nucleons would become unbound above a certain temperature / below a certain scale factor.

So the entropy gradient is generated by the universal expansion, which allows a series of more or less thermalised states (quark soup, nucleon soup, ion soup, atom soup, hydrogen soup) to cool until they turn into bound systems, thereby defining an arrow of time.

Some caveats...

1/ You'd expect gravity to mess this up, since it appears to behave time-asymmetrically, but since the big bang conspicuously didn't turn everything into black holes, I suspect there's more to the story that the GR view of gravity, which violates unitarity in singularities and hence must break down somewhere along the line. But we need a quantum gravity theory before we can get any further with that.

2/ Entropy is generally considered the result of coarse-graining - it's considered emergent, i.e. it can't be detected / doesn't exist on fine enough scales.Yet it appears to be a fundamental property of black holes, and of computation. How does this get integrated with Boltzman's conception of it as a measure of available vs occupied states? Does it, or are these different things? As far as I'm aware, no one knows.

Note: This model of time does not preclude that at some distant points of our space, time is running backward with respect to our time line.

It is in a sense inside black holes, which (according to GR) have a future directed spacelike singularity (like a reverse big bang). A black hole is a good model for how the laws of physics can cause time to go in either direction - stuff outside the event horizon is constrained by the entropy gradient generated by the big bang / cosmic expansion, while inside there is a future constraint which forces certain things to occur as matter approaches a certain point in space-time - loosely speaking, that is like time going backwards, forcing "unlikely" things to occur, like everything zeroing in on one location, something like the time reverse of gas escaping from a bottle.

[Kermit Rose]

On 4/22/2014 6:10 PM, LizR wrote:

On 23 April 2014 01:20, Kermit Rose <ker...@polaris.net> wrote:

On 4/21/2014 8:28 PM, LizR wrote:

Stated otherwise: you can only conclude that entropy will increase in one time direction

if it is somehow fixed to be very low at some point in (what seems to us to be) the remote past.

It as you say.  Entropy will always increase in the future time direction

ONLY IF  it was very low at some point in the remote past.

This means that Entropy always increasing implies that entropy was very low at some point in the remote past.

The language that John Clark was using made it look like he thought it was the other way around.

It looked like he thought that the low entropy in the remote past caused the higher entropy today.

It looked like he was confusing "if"  with "only if".


I give in the following a simple argument that if entropy always increases, then entropy was very low in the remote past.

In other words, I give in the following a simple argument that entropy always increases ONLY IF entropy was very low in the remote past.


Given:   Tomorrow, entropy will be higher than it is today.

Hypothesis:   Today is yesterday's tomorrow.

Conclusion:   Entropy is higher today than it was yesterday.

Conclusion:   Entropy was lower yesterday than it is today.


Kermit

[LizR]

On 23 April 2014 10:39, Kermit Rose <ker...@polaris.net> wrote:

Conclusion:   Entropy was lower yesterday than it is today.

Correct.

Entropy always increases or remains constant (to a VERY good approximation - remember it's a "coarse grained" concept).

However the maximum possible entropy - the "entropy ceiling" - also increases in an expanding universe. Hence in theory the universe can never (quite) run down (although a photon bath a fraction of a degree above absolute zero is pretty damn close to having run down)..

[Kermit Rose]

On 4/22/2014 7:11 PM, LizR wrote:

On 23 April 2014 10:39, Kermit Rose <ker...@polaris.net> wrote:

Conclusion:   Entropy was lower yesterday than it is today.

Correct.

Entropy always increases or remains constant (to a VERY good approximation - remember it's a "coarse grained" concept).

However the maximum possible entropy - the "entropy ceiling" - also increases in an expanding universe. Hence in theory the universe can never (quite) run down (although a photon bath a fraction of a degree above absolute zero is pretty damn close to having run down)..

Thank you Liz.

The forever expanding universe concept does seem to require time asymmetry.

Kermit

[LizR]

On 23 April 2014 11:49, Kermit Rose <ker...@polaris.net> wrote:

Thank you Liz.

No worries :)

The forever expanding universe concept does seem to require time asymmetry.

It appears to be the most likely cause of it, given that the laws of physics are (almost) time symmetric there isn't anywhere else (much) for it to come from.

So that pushes the problem back to where does the expansion of the universe come from? It appears that both eternal inflation and a "comp / theory of nothing" approach can at least address this.

[Bill Taylor]

On Wednesday, April 23, 2014 5:47:41 AM UTC+12, John K Clark wrote:

>> And if you conclude that the entropy tomorrow will almost certainly be larger than 

what it is today because there are vastly more disordered states than ordered ones

> But NOT because of that! 

 ...if there are vastly more disordered states than ordered ones then if you pick one at random...

This is your stumbling block.  If you declare "at random", meaning (obviously, for you)
"at random with uniform probabilities", your conclusion would be correct.

However, your conclusion is incorrect, because the choice of successor state
is NOT uniformly random.  It is highly non-uniform, because of the non-uniformity
of the transition probabilities.  TRANSITION PROBABILITIES - a concept which
you have studiously avoided mentioning/acknowledging, and which I must thus
conclude you are unfamiliar with, or you would not make such egregious mistakes.

Find any book on stochastic processes, (especially Markov processes, though
OC the universe need not be Markov!), to find out what these are, and perhaps
get a glimmering of why they are vital to the matter.

the chances are overwhelming it will be one of those more disordered states.

They are, but not for the trivial numerical reason you suppose.

|  yesterday has always had LESS Entropy than today not more (as you'd expect).

It is NOT "as we would expect" !!   This is your problem.

In a stochastic process the probability of (a type of) predecessor state
is NOT necessarily merely determined by the number of states of that type.
This is what you are glibly assuming, on the basis of uniformity, and you
are WRONG.  Because of the high degree of skewness in transition
probabilities, predecessor states are MORE LIKELY to be even
lower entropy than current states - as Kermit has already noted,
and as I have been labouring to explain with my clumsy comments
about dissipation, hysteresis etc.  These latter matters are a gross
summary of the myriads of transition probabilities and their effects.

OC initial conditions are vital too; but transition probabilities are
even more so. Initial conditions can easily "wear off", in stochastic
processes, but transition probabilities are always with us, like the poor.

-- Transitioning Taylor

**  The transition probabilities you will always have with you,
**  but the initial conditions you will not always have with you.

[Bill Taylor]

On Wednesday, April 23, 2014 10:39:18 AM UTC+12, KermitRose wrote:

It as you say.  Entropy will always increase in the future time direction

 

True, AFAWK.  (Though Liz's point about gravity not yet being taken care of
is a good one, from a good post).
 

ONLY IF  it was very low at some point in the remote past.

True, to within ignoring googolpexly infinitesimal chances.

 
 |  This means that Entropy always increasing implies that entropy was very low at some point in the remote past.

Yep.

 |  The language that John Clark was using made it look like he thought it was the other way around.

Yes, he was and it is bad, though most do it, like Zeh.

 | It looked like he thought that the low entropy in the remote past caused the higher entropy today.

He would say this, I deny it, and it is indeed a very silly thing to say. 
It is transition probabilities which do the "causing".

 | It looked like he was confusing "if"  with "only if".

Perhaps, but it is better to say he was confusing "efficient cause" with "formal cause".
Trans probs are the former, and the bigbang/expansion could be seen as the latter.

  |   Today is yesterday's tomorrow.

Tomorrow and tomorrow and tomorrow, creeps on this petty pace from day to day.

-- William of Avon

[John Clark]

On Wed, Apr 23, 2014 at 12:50 AM, Bill Taylor <shirt...@hotmail.com> wrote:

>>if there are vastly more disordered states than ordered ones then if you pick one at random...
 

>This is your stumbling block.  If you declare "at random", meaning (obviously, for you) "at random with uniform probabilities", your conclusion would be correct.

 

Then I am correct period because the non-uniformity is the same in the forward time direction as the backward.
 

> However your conclusion is incorrect, because the choice of successor state is NOT uniformly random.  It is highly non-uniform, because of the non-uniformity of the transition probabilities.

 
Schrodinger's Wave Equation is reversible and completely deterministic and produces an exact output, but what it outputs are just probabilities of what something will do or has done.  So you can use Schrodinger to get a rough idea of what the electron you're looking at right now WILL BE doing one second from now, and you can also use it to get a EQUALLY rough idea of what the electron you're looking at right now WAS doing one second ago. The probabilities or uncertainty or fuzziness or whatever you want to call it is exactly the same in both time directions. So I ask you yet again, how can something as symmetrical as that produce something as unsymmetrical as the arrow of time?

 

> TRANSITION PROBABILITIES - a concept which you have studiously avoided mentioning/acknowledging

 

Then what sort of probabilities have I been talking about all this time? Non-transition probabilities? Or maybe transition non-probabilities?  OMG I think it was non-transition non-probabilities! 

 

> and which I must thus conclude you are unfamiliar with, or you would not make such egregious mistakes.
 

And I must thus conclude that Caltech physicist Sean Carroll made the same egregious mistakes that I did and lacks the profound understanding  of probabilities that you possess because he's saying the same sort of things that I am, such as:  

 
"An omelet is higher entropy than an egg because there are more ways to re-arrange its atoms while keeping it indisputably an omelet, than there are for the egg. That provides half of the explanation for the Second Law: entropy tends to increase because there are more ways to be high entropy than low entropy. The other half of the question still remains: why was the entropy ever low in the first place?"
 

And:

 
"The first mystery of the arrow of time is that it's nowhere to be found in the fundamental laws of physics. Those laws work perfectly well if we run processes backwards in time."
 

And:

 
"The observed macroscopic irreversibility is not a consequence of the fundamental laws of physics, it's a consequence of the particular configuration in which the universe finds itself. In particular, the unusual low-entropy conditions in the very early universe, near the Big Bang. Understanding the arrow of time is a matter of understanding the origin of the universe."
 

> Find any book on stochastic processes,

 
I would bet money I've been reading books on stochastic processes longer than you have; at any rate I have a hunch I understand it better than you.
 

 > especially Markov processes,

 
In a Markov chain as in the universe some transitions are more likely than others, but being a higher entropy state doesn't make it more likely or less likely that the laws of physics will put the world into that particular state, it's just that there are ENORMOUSLY more such high entropy states than low, so we'll almost certainly end up in one of those high entropy states. So that explains half of the Arrow of Time.
 
What about the other half? Well...by the same logic we almost certainly came from one of those far far more numerous high entropy states. The only trouble is we didn't. The reason we didn't has nothing to do with the laws of physics, it has to do with initial conditions.

 

> the universe need not be Markov!

 

It doesn't matter if it is or isn't, although one thing both Markov Chains and the universe have in common is that neither is symmetrical with regard to time. The question is why?

 

>> yesterday has always had LESS Entropy than today not more (as you'd expect).

 
> It is NOT "as we would expect" !!   This is your problem.

 

Explain to me why this isn't your problem too. The laws of physics will transform the present state of the universe into a different state tomorrow, and because there are VASTLY more states that have higher entropy than today than lower entropy than today it's virtually certain that the laws of physics will put the universe into one of those higher entropy states tomorrow, scientific notation is not powerful enough to describe the probability that they won't. But there is no grand conspiracy among the laws to do this, it's just that almost any change of any sort will almost certainly result in higher entropy because there are more of them. And if you have found another reason why entropy will be higher tomorrow than today I would very VERY much like to hear about it!
 
And it's the same in the other direction. Of all the states that the laws of physics could have transformed into the present state of the universe high entropy states outnumber low by a astronomical (much too weak a word but the best I could find) margin. And yet yesterday was in one of those extraordinary rare low entropy states! The only explanation is that yesterday was closer to the initial condition state than today and that initial condition (the Big Bang) was very low entropy. 

 

> In a stochastic process the probability of (a type of) predecessor state is NOT necessarily merely determined by the number of states of that type.

 

It would be unless there is a fundamental law that favors high entropy over low, but there is no such law. It is possible that all the air molecules in the room you're reading this in go to the other side of the room and you suffocate, and such a state is not one bit more unlikely than any other state for the air in your room to be in; but you are in little danger because such low entropy states are vastly outnumbered by much higher entropy states where the air is more evenly distributed. 

 

> Because of the high degree of skewness in transition probabilities

 

At the microscopic level not one of the fundamental laws of physics is skewed in the direction of more entropy or in the direction of less for that matter, and yet at a larger scale we always observe that entropy increases. But we know there are enormously more high entropy states than low, so the second law of thermodynamics can be explained if and only if the Big Bang was very low entropy. 

 

> The transition probabilities you will always have with you

 

No, if you just wait a while sometimes probabilities become certainties; there is not one chance in 100 million that I won the lottery last week, there is one chance in infinity, exactly zero percent probability.

 

> but the initial conditions you will not always have with you.

 

No, some initial conditions can have a infinitely (and not just very long) reach
 
 John K Clark