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Author Topic:   Thermodynamics and The Universe
cavediver
Member (Idle past 1898 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 1 of 186 (382977)
02-06-2007 2:28 PM


In the recently closed thread, our new member EODoc made some claims regarding the nature of the universe, inspired by consideration of the laws of Thermodynamics. These are oft-repeated claims by the creationist crowd and I would like to propose a thread where we can discuss this.

I open with my reply to EODoc but would encourage others to join in with comments, questions and refutations :) Big Bang & Comsology of course!

In short, the fact that we exist demonstrates that possibility 1 cannot be true because if the universe is infinitely old then such a state (the heat death) would have already been reached.

Heat death is a state that exists in an open or flat Friedmann ( or closed Lemaitre :)) Robertson Walker universe. None of these are universes that have always existed. There are many possibilities for eternally existing universes that do not have thermodynamic problems. Next?

I hope you can see quite clearly that if the universe created itself then we have a little problem called the first law of thermodynamics. Let me know if you need me to expound on what the 1st law is in real terms.

Please do, as I would love to hear your ideas on thermodynamics in a closed universe. First off perhaps you would like to define "energy" as that seems rather important for your 1LoT. And what would happen to your 1LoT as your definition of energy breaks down and becomes fairly meaningless (as all mine do when we get back toward t=0 in a F(L)RW universe)

I hope you can see quite clearly that if the universe created itself then we have a little problem called the first law of thermodynamics

No, on the contrary, the 1LoT has the problems when we enter regions of the universe where naive ideas of energy and heat and such-like make little to no sense.

I don't think you can argue against this except by saying that the laws of thermodynamics don't apply to the universe as a whole but it would be hard to make such an argument based on known science

Thermodynamics applies to systems of multitudes of classical particles. To consider the Universe as a whole is to have one very unclassical particle. How exactly does Thermod even begin to apply?


Replies to this message:
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AdminNosy
Administrator
Posts: 4754
From: Vancouver, BC, Canada
Joined: 11-11-2003


Message 2 of 186 (382989)
02-06-2007 2:58 PM


Thread moved here from the Proposed New Topics forum.
  
happy_atheist
Member (Idle past 3169 days)
Posts: 326
Joined: 08-21-2004


Message 3 of 186 (383002)
02-06-2007 4:02 PM
Reply to: Message 1 by cavediver
02-06-2007 2:28 PM


cavediver writes:

Thermodynamics applies to systems of multitudes of classical particles.

This was one of the most amazing things I saw when I was studying physics. I hated thermodynamics, but when I took a statistical mechanics course and saw the well known 'laws' drop out from simple quantumn mechanics (ha!) and some approximations that can only be made with extremely large numbers of particles it was quite eye opening. I only wish I'd been better at physics overall so I could have made a go of it. Seeing this thread again has made me want to go find my physics texts and start learning all over again!

But it does bring to light how hard it is for a non-physicist to grasp how their every-day point-of-view governed by common sense rules is totally non-applicable to the universe as a whole. I certainly look forward to EODoc's response (or anyone else who decides to take the challenge).


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Chiroptera
Member
Posts: 6800
From: Oklahoma
Joined: 09-28-2003
Member Rating: 7.2


Message 4 of 186 (383010)
02-06-2007 4:36 PM
Reply to: Message 1 by cavediver
02-06-2007 2:28 PM


Hey, cavediver. Wave me off if this is getting off of the topic you wanted to discuss.

I do find it amusing that people try to apply "physical laws", which are used to describe phenomena within the universe, to the "creation of the universe" (whatever that even means!) itself.

Take the law of conservation of energy, for example. Even beside the very good points you made, the law of conservation of energy simply states that at each point in time, the energy of a closed system will remain the same. Well, the "creation of the universe" certainly does not violate this. "Before" the universe existed, there was no time -- hell, "before the universe existed" is itself a nonsensical phrase. "Before" the creation of the universe, there were no "points of time". So even in a classical universe existing for a finite amount of time, there is no violation of the law of conservation of energy: there was no point in time when the energy content of the universe was different.

God, what a weird topic. This is going to wear out the quote key on my keyboard.


This world can take my money and time/ But it sure can't take my soul. -- Joe Ely
This message is a reply to:
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cavediver
Member (Idle past 1898 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 5 of 186 (383200)
02-07-2007 1:12 PM
Reply to: Message 4 by Chiroptera
02-06-2007 4:36 PM


I do find it amusing that people try to apply "physical laws", which are used to describe phenomena within the universe, to the "creation of the universe"

Yep, though scientists have been guilty of this in trying to explain creation ex nihilo in terms of pair-creation and the like!

So even in a classical universe existing for a finite amount of time, there is no violation of the law of conservation of energy: there was no point in time when the energy content of the universe was different.

Nicely put... will use that myself :) It's easier than trying to explain the breakdown in definition of energy at the t=0 point.

God, what a weird topic. This is going to wear out the quote key on my keyboard.

:laugh: Yeah, noticed that myself a month or so back, where every fourth word I wrote was in "quotes"... I guess it's that or bring out the heavy maths. You may now appreciate what I meant a while back when I said that very few scientists actually have a real grasp of the Big Bang. All the bits for t > 10e-33s are easy, it's that bit from t=0 that gets you ;)


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cavediver
Member (Idle past 1898 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 6 of 186 (383205)
02-07-2007 1:23 PM
Reply to: Message 3 by happy_atheist
02-06-2007 4:02 PM


This was one of the most amazing things I saw when I was studying physics. I hated thermodynamics, but when I took a statistical mechanics course and saw the well known 'laws' drop out from simple quantumn mechanics (ha!) and some approximations that can only be made with extremely large numbers of particles it was quite eye opening.

Funny, I was exactly the same. I still hate traditional TD but stat mech is fascinating.

Seeing this thread again has made me want to go find my physics texts and start learning all over again!

Then my job is done :)

But it does bring to light how hard it is for a non-physicist to grasp how their every-day point-of-view governed by common sense rules is totally non-applicable to the universe as a whole

Quite. And it's not just the non-physicist. EODoc is a perfect example of a physicist (physical chemist) who is a complete fish-out-of-water when it comes to considering fundemental cosmology - no better and in fact considerably worse than many of the well-informed laymen who frequent EvC. To be fair, my knowledge of chemistry is pretty awful...


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Percy
Member
Posts: 18842
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.5


Message 7 of 186 (383240)
02-07-2007 2:42 PM
Reply to: Message 6 by cavediver
02-07-2007 1:23 PM


cavediver writes:

Quite. And it's not just the non-physicist. EODoc is a perfect example of a physicist (physical chemist) who is a complete fish-out-of-water when it comes to considering fundemental cosmology - no better and in fact considerably worse than many of the well-informed laymen who frequent EvC. To be fair, my knowledge of chemistry is pretty awful...

I fear we may have lost EODoc, I haven't seen him since AdminPD closed that other thread.

My knowledge of chemistry is pretty bad, too, but we are both cognizant of how little we know of chemistry. How does someone, anyone, reach the PhD level without passing association with so much knowledge as to force the realization of how little one knows. One thing you can say for EODoc, though - he sure wasn't afraid to make a mistake!

--Percy


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SplifChief
Junior Member (Idle past 4504 days)
Posts: 5
From: FL
Joined: 02-07-2007


Message 8 of 186 (383270)
02-07-2007 4:09 PM


Hi there. I know I am just jumping in, but I just wanted to contact you. I posted a question that admin said didn't justify a thread, but suggested that maybe you could answer.

How can the observable universe be larger than the age of the universe if nothing travels faster than the speed of light?

If for example 2 elements were relatively close at the BB, and now one is in our galaxy and the other in the far reaches of the observable universe, how could it have traveled more than 13+ light years away given the time it has been traveling?

Please excuse any misuse of terms, just trying to get my question across in an attempt to get past this mental block.

Thanks


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kuresu
Member (Idle past 768 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 9 of 186 (383275)
02-07-2007 4:22 PM
Reply to: Message 8 by SplifChief
02-07-2007 4:09 PM


i don't know if this answer is right, but . . .

our universe is 13 billion years old. let's picture the universe as a beach ball. the center of this ball is where the big bang occurred. light travels in all directions from the center. the universe (beach ball) is thus 26 light years in diameter. the age, then, is the radius.

again, not sure if this is the right answer, but . . .

oh, and welcome to the boards.


Question. Always Question.

" . . .and some nights I just pray to the god of sex and drugs and rock'n'roll"--meatloaf

Want to help give back to the world community? Did you know that your computer can help? Join the newest TeamEvC Climate Modelling to help improve climate predictions for a better tomorrow.


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NosyNed
Member
Posts: 8860
From: Canada
Joined: 04-04-2003
Member Rating: 4.8


Message 10 of 186 (383294)
02-07-2007 5:01 PM
Reply to: Message 8 by SplifChief
02-07-2007 4:09 PM


Expansion speed
If you had browsed, tediously, the cosmology threads you would find reference to the fact that the expansion of the universe is NOT anything moving through space (which is limited to light speed). It is the expansion of space itself. This is not limited to light speed.

The expansion between two points in space is proportional to the distance between them. At some point this means that two galaxies may be receding from each other at greater than light speed even if they are not moving.

If that is confusing try this analogy.

Put ants on a big sheet of rubber. Now stretch the rubber bigger and bigger. The ants get further apart without 'moving' (on the sheet) at all.

Ants that started further apart have more stretching rubber between them so they move apart faster than ants that started closer together.


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SplifChief
Junior Member (Idle past 4504 days)
Posts: 5
From: FL
Joined: 02-07-2007


Message 11 of 186 (383315)
02-07-2007 5:42 PM
Reply to: Message 10 by NosyNed
02-07-2007 5:01 PM


Re: Expansion speed
OK, so I think I've got it now. The expansion of space itself is not subject to any speed limitations.

Should this give the appearance of a stretching affect as we observe light from these galaxies moving with space at speeds greater than the speed of light?


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NosyNed
Member
Posts: 8860
From: Canada
Joined: 04-04-2003
Member Rating: 4.8


Message 12 of 186 (383318)
02-07-2007 5:48 PM
Reply to: Message 11 by SplifChief
02-07-2007 5:42 PM


Light stretching
Should this give the appearance of a stretching affect as we observe light from these galaxies moving with space at speeds greater than the speed of light?

Yes, this is the "red shift" you read about a lot. As the recession velocity goes up the light from a given galaxy is shifted (stretched) to longer and longer wave lengths. As the recession velocity approaches c (light speed) the wave length is stretched to infinity and the galaxy is no longer visible.

(warning: I'm an amateur so wait for cavediver's corrections before swallowing completely) :)


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Buzsaw
Inactive Member


Message 13 of 186 (383348)
02-07-2007 6:55 PM
Reply to: Message 4 by Chiroptera
02-06-2007 4:36 PM


Chiroptera writes:

So even in a classical universe existing for a finite amount of time, there is no violation of the law of conservation of energy: there was no point in time when the energy content of the universe was different.

1. The above statement as well as if the universe is a closed and finite system makes my point in another thread that there indeed was no before the universe and no outside of the universe if it is a closed, bordered and finite system. Thus our resident Biblical theists do indeed have the problem that I raised in my thread that the Biblical god in whom they believe could not possibly exist on the basis of such a universe.

2. I don't see how you can exempt laws of physics from the science of a system origin hypothesis which itself defies the the laws observed within the system. Isn't that what you are forbidding ID creatonists to do? Essentially you are assuming that the entire energy of the universe popped into existence suddenly from nothing. The only other alternative is that the Universe is infinite without beginning or end as we claim for the intelligent designer, the source of all existing energy.


BUZSAW B 4 U 2 C Y BUZ SAW ---- Jesus said, "When these things begin to come to pass, then look up, and lift up your heads, for your redemption draws near." Luke 21:28
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jar
Member
Posts: 31262
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.8


Message 14 of 186 (383354)
02-07-2007 7:05 PM
Reply to: Message 13 by Buzsaw
02-07-2007 6:55 PM


Thus our resident Biblical theists do indeed have the problem that I raised in my thread that the Biblical god in whom they believe could not possibly exist on the basis of such a universe.

ROTFLMAO

No problems for the GOD we believe in Buz, just for the little crappy goddlet you created and worship.

But what does any of that have to do with the Topic?


Aslan is not a Tame Lion
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Doddy
Member (Idle past 4164 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 15 of 186 (383362)
02-07-2007 7:32 PM
Reply to: Message 12 by NosyNed
02-07-2007 5:48 PM


Re: Light stretching
NosyNed writes:

As the recession velocity approaches c (light speed) the wave length is stretched to infinity and the galaxy is no longer visible.

I remember reading that this isn't true, but I can't remember the theoretical reasoning. But I do know that we can see galaxies outside of the Hubble sphere (which were receding superluminally when they emitted the photons that our telescopes can see).

I'll have to wait for the explanation too. Something about the Hubble sphere growing, I think...?


"Der Mensch kann was er will; er kann aber nicht wollen was er will." (Man can do what he wills but he cannot will what he wills.) - Arthur Schopenhauer
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