Talk about entropy and cyclical cosmology from spacetime thread

[Michael Mooney]

Moderation Note: The following 10 posts were moved from What is "spacetime" really? where they were off topic and deserving of their own thread.

Originally Posted by Pyrotex

The Cosmos is, by definition, a closed system, as it is "all that is".
Entropy is NOT the sum total of all matter and energy as implied by MM.
Entropy is a measure of order/disorder of that matter and energy.
If a Cosmos had all its matter and energy at one point, then entropy would be maximum.
If a Cosmos had all its matter and energy equally spread out everywhere, with no gradients, then entropy would be minimum.

First, you have it backwards.
From The Free Dictionary on Entropy:

"1. Symbol S For a closed thermodynamic system, a quantitative measure of the amount of thermal energy not available to do work.
2. A measure of the disorder or randomness in a closed system.
3. A measure of the loss of information in a transmitted message.
4. The tendency for all matter and energy in the universe to evolve toward a state of inert uniformity.
5. Inevitable and steady deterioration of a system or society.

So, if the universe just kept expanding and dissipating matter/energy, " toward a state of inert uniformity"... it would just "run down"... the state of maximum entropy.

If, on the other hand, there is enough mass in the universe (the "missing matter/energy" is found) all of it will be "caught in the universal gravitational net" (at the extreme of its expansive phase) and brought back for another in a perpetual series of bangs and crunches.

Actually I know very well what entropy is and I never implied that "Entropy is... the sum total of all matter and energy"
The sum total of all matter and energy in the universe is never increased or diminished. It is presently in the process of expanding *toward* maximum entropy, but if there is enough mass for *critical cosmic mass* for gravitational reversal, it will all come back and start over again... with *no loss.*

Michael

[maddog]

Originally Posted by Michael Mooney

First, you have it backwards.
From The Free Dictionary on Entropy:

Pyrotex,

This has to be one for the History books, yet here is where I agree with Michael, Entropy
is measured against a Closed System. Thus it would be fine to consider the Entropy
of the Universe (as long as it was "Closed"). With a lot of models today considering
other geometries than closed, proper boundary condition may need be laid out (that I
have seen not).

maddog

[modest]

Originally Posted by maddog

Pyrotex,

This has to be one for the History books, yet here is where I agree with Michael, Entropy
is measured against a Closed System. Thus it would be fine to consider the Entropy
of the Universe (as long as it was "Closed"). With a lot of models today considering
other geometries than closed, proper boundary condition may need be laid out (that I
have seen not).

maddog

I have to agree with Pyrotex and it's a very well-known problem with models of an eternal (as in no beginning) cosmos. Entropy can only increase and the entropy of the visible universe is not at a maximum. Hoyle's steady state model solves this problem by allowing new hydrogen to spontaneously be generated as the universe expands, but this in turn breaks the first law of thermodynamics (conservation of energy). Anyone claiming there is no beginning to the matter in the universe is ultimately faced with an entropy problem.

I don't think allowing the universe to be open can solve this problem.

~modest

[Michael Mooney]

Me:

I have consistently argued that more simple "dark matter"* is being found all the time with better detectors, so that6 the "missing matter problem" against reversal/implosion may not be a "problem much longer. (*Ordinary matter not emitting or reflecting light.)
And then, as in the quote above... whatever "dark energy" and "dark matter" might be (??) could add to the equation for viable critical cosmic mass.

Modest:

I'm afraid this is a subject you can't really gloss over with a few loose phrases. Dark energy (i.e. the cosmological constant / Lambda) which the wiki article mentions is an entirely different thing from dark matter. Rather than being an enigmatic concept which fixes your broken philosophy, it is an energy density attributed to empty space. As such, I'm sure you would reject it ardently if you knew anything about it.

Modest,
You continue *as always* to misrepresent what I write.
I didn't "gloss over" "dark energy" and "dark matter." I don't understand what they (theoretically) are... or even *if* they "are," as clearly indicated in my parenthetical (??.)

One** of the classic objection to a cyclic cosmos is the "missing matter problem" which is becoming less of a "problem" all the time as more matter is being detected, as I clearly stated above.... with or without the help of "mystery matter/energy" in its latest theoretical incarnation as "dark matter/energy."

Another is the "entropy" objection, which I have again addressed just above in reply to Pyrotex.

Yet another objection (to the classical "Bang/Crunch" theory) is the dynamic of the "Bang" itself... which I have addresssed in brief several times on this thread as the "multiple bangs and crunches cosmic juggling act" as a series of up-scaled supernovae-like bangs sending out cosmic matter like "supernova remnants" even as more matter is collapsing inward.

I think it was Pyrotex who observed that this thread is a bungled up mess, and I volunteered that your consistent mangling of my meaning is a primary cause.... and I cited the most recent example at the time.
Again I ask you to get off my case, as you show no comprehension of my meaning intended in any given post, as above.
Michael

[maddog]

Originally Posted by modest

I have to agree with Pyrotex and it's a very well-known problem with models of an eternal (as in no beginning) cosmos. Entropy can only increase and the entropy of the visible universe is not at a maximum. Hoyle's steady state model solves this problem by allowing new hydrogen to spontaneously be generated as the universe expands, but this in turn breaks the first law of thermodynamics (conservation of energy). Anyone claiming there is no beginning to the matter in the universe is ultimately faced with an entropy problem.

I don't think allowing the universe to be open can solve this problem.

~modest

Modest,

I was only pointing out the issue with Entropy and Boundary Conditions. Yes for matter and
the Universe as we know it to be, Entropy always increases (for the most part).

I do remember a Biophysicist friend when I was in college and he was having Entropy
issues with any System he created where living things were included (Terrarium for
example). He found Entropy deviated from the predicted path for inanimate matter.
His professors had said his error was inappropriately applying his Boundary Conditions.
Of course that is slightly getting off topic.


maddog

[modest]

Originally Posted by maddog

Of course that is slightly getting off topic.

I agree. I myself am guilty of pulling this thread off topic lately. As I think this thread has been a good source of discussion and I think it deserves our respect in keeping it on topic, I will move any subsequent posts which focus on anything not related to "What is "spacetime" really?" elsewhere.

Michael, I'm sure you'll want to respond to some of the cosmology stuff I wrote above, and I'm sure that's fine. But, hopefully we can put a quick end to discussion of entropy and cyclic universe models and whatnot in this thread.

~modest

[modest]

Originally Posted by Michael Mooney

entropy... is not valid for cosmos as a whole... in which no energy/matter is ultimately lost.
Can you even 'wrap your head around" this difference?

Can you please provide a scientific reference supporting this claim? Doing so is a requirement of the Hypography site rules.

By my understanding the laws of thermodynamics work on the universe as a whole most especially because "no energy is ultimately lost" (it is a closed system). As the second law of thermodynamics is applied to the universe we find the universe will eventually reach a state commonly referred to as "heat death".

The heat death is a possible final state of the universe, in which it has "run down" to a state of no thermodynamic free energy to sustain motion or life. In physical terms, it has reached maximum entropy. The hypothesis of a universal heat death stems from the 1850s ideas of William Thomson, 1st Baron Kelvin who extrapolated the theory of heat views of mechanical energy loss in nature, as embodied in the first two laws of thermodynamics, to universal operation.

Heat death of the universe - Wikipedia, the free encyclopedia

~modest

[watcher]

michael,
entropy is unassailable.
in time the universe would simply spaced out
our universe is like an echo that fades away in a one way trip to oblivion.
but don't lose heart, your cyclic model is still feasible in a multi dimensional universe model. where rebirth of new universe happens and assures that existence in general would not cease.
ironically you are against multidimensionality of it.
so you see your ideas of space and time is not even compatible with your endless cycle cosmology.

[lawcat]

Originally Posted by modest

Can you please provide a scientific reference supporting this claim? Doing so is a requirement of the Hypography site rules.

By my understanding the laws of thermodynamics work on the universe as a whole most especially because "no energy is ultimately lost" (it is a closed system). As the second law of thermodynamics is applied to the universe we find the universe will eventually reach a state commonly referred to as "heat death".



~modest

True. Entropy is "unuseful" energy within environment. It is defined as a heat transfer relationship between two objects -- entropy = heat (kJ/kg)/ temperature (Kelvin).
For example, if 3000 Kj/kg of heat flow from planet A to planet B, and planet A has temperature T=300K, then entorpy of planet A is 3000kJ/kg/300K = 10 kJ/kgK (planet A has lost some useful energy).

If universe has mass and no-mass, then theoretically all mass energy can be converted to heat in no-mass. Then, mass would have maximum entropy, and no real useful energy.

I don't believe this can happen, for I believe that mas can be reconstituted, and created from space and time.

[Michael Mooney]

Originally Posted by modest

Can you please provide a scientific reference supporting this claim? Doing so is a requirement of the Hypography site rules.

By my understanding the laws of thermodynamics work on the universe as a whole most especially because "no energy is ultimately lost" (it is a closed system). As the second law of thermodynamics is applied to the universe we find the universe will eventually reach a state commonly referred to as "heat death".

~modest

I will provide the logical contex for the claim, then document sources for the classic "Bang/Crunch" cosmology if required.

Context: The universal law of conservation of matter and energy (and plasma as a transitional state) states that nothing is ever created or destroyed but only changes form.

The Merriam Webster Online Dictionary defines entropy, as applied to the universe as a whole as follows:

2 a: the degradation of the matter and energy in the universe to an ultimate state of inert uniformity b: a process of degradation or running down or a trend to disorder

The "universal gravitational net" part of the classic "Bang Crunch" cosmology states that if the "missing matter" is found (and that is happening... which will revive the supposedly debunked "bang/crunch") then all matter/energy/plasma in the universe will be ultimately pulled back into a Big Crunch in prep for the next Big Bang.
It is important to notice that nothing is lost in this model, and tho the model was supposed to have been debunked, the "found matter" to make "critical cosmic mass" for this gravitational reversal possible may well herald a revival of "my favorite cosmology" as above (and shared several times in this thread.)

Further contex... a reply to NomDePlume on the entropy issue:

This (the universal law of conservation of matter/energy) means that there is no loss of anything, cosmically speaking. So the second law of thermodynamics, so clearly valid for "isolated systems" in which there is "space" outside the system for, say heat to escape into... making the isolated system "lose steam" ... entropy... is not valid for cosmos as a whole... in which no energy/matter is ultimately lost.

So... entropy as above defined *will not happen* if the missing matter is found to bring it all back together for another in a perpetual series of bangs and crunches.
There would be no energy loss ultimately, and no " ultimate state of inert uniformity...(the)... process of degradation or running down or a trend to disorder.
The outer extreme of the expansion phase would, perhaps *approach* maximum entropy, but like the ultimate melodrama, the "gravitational net" powered by the required "critical cosmic density" would save the universe from such max entropy and bring it all back for the next "re-birth."

I agree that if the challenge against the bang/crunch model continues to insist that it is debunked by "expanding space" that a new thread will be required to continue the debate.

Still, such a debate must ultimately come back to what it is that "expands" if space retains its original meaning as emptiness... which it does in my vocabulary. (And if it disappears if the stuff in it disappears, what *was* it anyway?...)

Then (in such a thread) I will engage the *dogma* that "stuff" does not expand, explosion-wise out into infinite, empty space.

Michael