Eternal Return

steenpat

I'm sure this topic has been talked about ad infinitum, but I'd like to suggest a new angle.
Here, I will be referencing the work of Nietzsche (actually from Indian philosophers originally), and the concept which posits that the universe has been recurring, and will continue to recur, in a self-similar form an infinite number of times across infinite time and or infinite space.
(http://en.wikipedia.org/wiki/Eternal_return)

Poincare's theorem of recurrence is what gives strength to this concept, as it states that certain systems will, after a sufficiently long time, return to a state very close to the initial state. (http://en.wikipedia.org/wiki/Poincare_recurrence)

However, according to some critics, the second law of thermodynamics says this can't happen since entropy can never decrease. (same wiki entry but no citation).

Now, is it necessary that entropy would need to decrease in order for a recurrence to happen? Assuming the state of the universe has a finite amount of configurations, and that energy is conserved, given a long enough time frame then could these configurations come close to their original form once more as a natural progression of the system?

It seems that current cosmology models would destroy this concept by the simple fact that the universe will reach a heat death scenario (http://en.wikipedia.org/wiki/Heat_death), in which case it doesn't seem like any matter will be around to make reconfigurations possible in the future.

But, if quantum fluctuations can create more big bangs, and this can seemingly happen an infinite amount of times without any restriction, it would seem inevitable that everything would recur arbitrarily close, wouldn't it? (http://elshamah.heavenforum.com/t65-...m-fluctuations)

I don't know if my reasoning is correct, maybe someone else can add a little input. I suppose that Poincare recurrence if possible, doesn't describe Eternal Return so much as Eternal Alternatives.

baywax

Philosophically it occurs to me that if the entire universe is responsible (ie: is the origin) for one wave of energy... then the opposite could well be true as well. This may coincide with the idea of quantum fluctuations. However, the signature contained in one wave of energy may well be all that is needed to start another universe that, not too surprisingly, would resemble the one that contained the wave(icle).

apeiron

You'll note that the wiki article actually says...

So this is where the expansion/cooling of the universe bites. The volume expands and everything gets too spread out to ever find itself again in the same arrangement.

As it also gets too cold, then there is no free energy field to fluctuate. The likelihood of spontaneous creation would be as infinitesimal as the universe was infinite (in size and coldness).

steenpat

That would seem to be the result. However, it's left unanswered questions such as, how was the Big Bang possible in the first place? It would seem like the Big Bang and the second law are somehow at a paradox, or at the quantum level the second law can be violated somehow.

ZapperZ

Isn't this really a question on the physical validity of the Big Bang? If it is, then this is not a philosophy question, but rather a question that you should get clarified from those with expertise in cosmology ( ---> points to the Cosmology).

Zz.

steenpat

I suppose so. Didn't mean to get off-track; just adding on to the previous comment in support for my original thesis.

apeiron

This is kind of jumbling quite a few questions together.

The second law only states what will happen to entropic gradients - they will get dissipated, run down to their lowest state. But the big bang is about how a gradient even existed in the first place.

Eternal return does appear in violation of the second law in that it seems to say that the same gradient keeps reappearing, ready to be degraded all over again.

People still like to think the universe could re-collapse under its own gravity and so recreate its initial conditions, setting up a cyclic story. But dark energy has made that harder to argue now.

But I am prejudiced against recurence in general - it seems an ugly idea because it is just going around in circles and not getting anywhere!

bobc2

But there is also dark matter.

At a more fundamental level, the concept of causality is not fleshed out. Physics doesn't really want to include the more fundamental aspects of this question, and the philosophers are still nibbling around the edges.

The fundamental question is how do you have a flow of events for the universe--from the big bang to the big crunch (or whatever cosmological model posed)--when the universe actually appears to be a static 4-dimensional structure populated by 4-dimensional objects. Things in the universe did not actually occur in some time sequence--it was all there at the same time. Our perception of the continuous sequence of events actually is not a necesary part of physics, those things so far have to do with philosophy and religion (consciousness, absolute time, etc.).

So, back to the original question posed, putting the question in the context of 4-D objects, one would ask if the 4-dimensional univers resembles something like a single link of sausage, or does it resemble multiple links tied back onto itself--all of those sausages having been created at the same instant.

Notice there is no "bang" in the sense of some dynamic event. The bang is just a point at one end of a sausage link.

But where do the dynamics and laws of physics come from? In principle it can all be represented, mathematically, with geometrical descriptions relating the many faceted geometric patterns and symmetries of the 4-dimensional fabric.

apeiron

Which would be relevant how? Over enough time it would clump into blackholes and be radiated away.

Special relativity may make the timing of events observer-dependent, but locality is preserved. If a cause is in your past light cone, no observer can find it in your future. The temperature of the CMB also serves as a suitable univeral clock.

So while the speculation about recurrence can be constrained by relativity - just as it should be by thermodynamics and QM - I don't see it has much bite here.

The idea that reality just is a deterministic block is itself a radical ontological interpretation and can't be treated as something we should just believe here.

Or given dark energy now says no recollapse, a sausage that has a start but then no end!

And if you are arguing for block universes, then how does determinism bridge the singularity that GR would say pinches off each of your sausages?

bobc2

Why do you say it is a radical interpretation? Even when you invoke many universes to avoid determinism you still have not ridden yourself of the objective 4-D universe. You've just compounded the problem manyfold. And even if you invoke Berkely or Leibnitz you still have it--just in a different form. At best we can claim that the block universe really doesn't exist, but so far we just accept that there is a deep mystery about how nature pulls this off, i.e., having different observers living in different cross-sections of a 4-D universe without there actually being a block universe.

I should acknowledge "The Labyrinth of Time" in which Michael Lockwood, after asserting the strongest classical arguments for the block universe, goes on to present a quantum mechanical world view that gets around it.

I concede that is the prevailing view at this point. But we must be careful, because there still seems to be much to learn about what is out there in the universe and how it all behaves.

That's particularly easy for a block universe. In the absense of knowledge of how it came into being in the first place (maybe all at once, maybe putting in the complete world lines one after another, maybe starting at one end and working either backwards or forward...) it could have been constructed under one set of rules at the start and then another set of rules through the first 10-33 sec or so... That is, the construction did not have to be constrained to laws of physics as we know them. After all, we do not know whether an expansive hyperspace exists, nor would we have the foggiest idea of what laws or properties would be associated with such a construct.

To say nothing about a concept of time or consciousness.

Maui

A 4-D universe is not a universe(definitely not in the sense of a universe that can be spatially represented). At best, a 4D 'universe' is a plan, blueprint, script. How that script unfolds as we experience it is a different issue.

bobc2

Do you embrace the concept of an objective 3-D spatial universe?

Maui

An experienced objective 3-D spatial universe, yes.

bobc2

Careful. I assume you would want to avoid the road to solipsism. Do you acknowledge the existence of 3-D universes experienced by others?

If the universe must be experienced to exist, am I to take it that the universe did not exist, say 4 billion years ago, i.e., around the formation of the earth?

Or are you thinking more along the lines of a universe existence beginning with the Garden of Eden around 7000 years ago?

steenpat

The other problem I have with the second law of thermodynamics is that it assumes there actually is a macroscopic state. Given the fractal nature of the universe, it leaves that question open. I also concede that what we observe to be dark energy seems to be evidence against the possibility of any macroscopic collapse.

Eternal Return as a philosophical idea pertains to an individual's life. To paraphrase Nietszche, it could mean the existence of Heaven and Hell depending on your own life experience. I suppose my own existence has had its share of happy moments which I psychologically wish to relive, whether that is possible or not.

Given that time can be quantized infinitesimally, is there really a start?

brainstorm

The point of studying the idea of eternal return is not to evaluate whether its premises are physically possible. The point is to elaborate the logic of karma in a way that you can understand how it could be possible to experience the consequences of one's own actions as their recipient.

An eternal return universe would evolve according to all the known chains of cause and effect, including conscious and unconscious choices as causes for effects that go on to influence subsequent conditions. In this way, the world evolves various patterns of activities/behaviors. So, for example, if you walk up to your neighbor and kick him in the leg, he might be shocked at first but later decide to kick someone else in the leg when he gets upset at them because it became part of his vocabulary of violent-expressions. If this chain of cultural learning continues, many people will teach each other how to kick someone else in the leg by doing it to them.

Logically, if the universe repeats itself eternally, you would eventually be born again as a repetition of yourself, but in each iteration of your life, various aspects of different past events might be repeated - i.e. not every re-iteration of your life would occur in exactly the same way as the previous one. After all, the world keeps evolving according to the same physical laws and choices of actions that people make. But if kicking people in the leg remained popular until your "rebirth" in a future iteration of yourself, you might get kicked in the leg as a result of your own kicking of someone else in the leg in your previous life.

Since this is getting into reincarnation logic, it's worth mentioning that you can also look at the return of actions within the same lifetime. I.e. you could get kicked in the leg a year after you kicked your neighbor in the leg just because that action already circulated around back to you. To conclude, this is why Gandhi talked about "himsa" and "ahimsa" (i.e. violence and resistance-of-violence). He believed that the kick-in-the-leg would come back to you but so could the act of resisting violence. So if you got angry at your neighbor and just told him why you were angry, he might do the same, and someone who eventually got angry at you might just tell you why instead of kicking you.

JoeDawg

Just to clarify, Nietzsche's concept has nothing to do with rebirth or physics, or any kind of metaphysical recurrance. Nietzsche used the concept as an affirmation of life: Would you knowing what you know, live every minute of your life, no changes, over again... infinitely?

He was encouraging people, to live their lives 'as if' this was the case, and to refuse regret and embrace their life as it is lived. It had nothing to do with quantum fluctuations or karma.

Just sayin...