Entropy in big bang vs big crunch

In summary, the conversation discusses the concept of entropy in relation to the big bang and the big crunch. It is mentioned that there is no generally accepted explanation for the difference in entropy between the two events. The theory is linked to the absence of observed white holes in the universe. The conversation also delves into the concept of entropy and how it relates to the number of particles and forces present in a system. The speaker also mentions their own theory, which suggests that the difference in entropy can be explained by the expansion of spatial dimensions during the big bang.
  • #1
rjbeery
346
8
Is there a generally accepted Physics explanation of the apparent "small entropy" of the big bang vs the apparent "large entropy" of theoretical the big crunch?
 
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  • #2
AFAIK, there isn't a generally accepted explanation. If you want at least some good discussion on this though, it's gone over in some detail in Roger Penrose's 'The emperors new mind'. I would summarise his view but I'd need to refer to the book and have lent it out currently :(

I remember that it is linked to the theory as to why we have no observed white holes in the universe though (and why it's predicted that there will be none).
 
  • #3
Well isn't entropy the measure of how much much different states you can have in a system(i.e. the measure of chaos). That is - if I understand the concept correctly(Do I?).
Then it seems logical that at the time of the big bang when the number of particle types and fundamental forces was at its lowest(or so they say) and energy was distributed most evenly in space entropy was also small. And take today(going towards the big crunch can only make it worse) - we probably have as many particles as there are physicists :P
 
  • #4
Hmm, thanks for the response workmad3 but I've read The Emperor's New Mind (it's sitting right by my keyboard in fact) and I have not been left with the impression that Penrose even addressed the issue. When you get a chance please do refer to the book for me (with a page number), because there is a decent chance that he does answer the question but I just didn't "get it".

Anyway, I have my own answer, and wouldn't mind feedback. It is clear that the order of a point in dimensionless space is infinite, so entropy = zero at the big bang. I have seen some describe the big bang as not only an expansion of mass and energy, but also of spatial dimensions themselves - this would make it meaningless to ask what was "there" before the big bang occurred. However, if these dimensions persisted during a big crunch then it seems to me that entropy would approach infinity because the backdrop is now continuous and possibly infinite (i.e. the point has many/infinite locales).

In other words, entropy of a point in dimensionless space = zero, while entropy of a point in dimensioned space = infinity (or approaches infinity as the dimension grows, if one wants to reject the continuous nature of space)...
 

1. What is entropy in the context of the big bang and big crunch?

Entropy is a measure of the disorder or randomness in a system. In the context of the big bang and big crunch, it refers to the amount of disorder or randomness present in the universe at different stages of its evolution.

2. How does entropy change during the big bang and big crunch?

During the big bang, entropy is thought to have been very low, as the universe was highly ordered and uniform. As the universe expanded and cooled, entropy increased, leading to the formation of stars, galaxies, and other structures. In a big crunch scenario, entropy would decrease as the universe collapses back into a highly ordered state.

3. Does entropy play a role in determining the fate of the universe?

Yes, entropy is thought to play a crucial role in the eventual fate of the universe. The second law of thermodynamics states that entropy always increases in a closed system, which suggests that the universe will continue to expand and become more disordered over time. This is known as the "heat death" of the universe.

4. Can entropy be reversed in the big crunch scenario?

No, it is unlikely that entropy can be reversed in the big crunch scenario. The collapse of the universe into a highly ordered state would require a significant decrease in entropy, which goes against the second law of thermodynamics. However, some theories suggest that a big crunch may lead to a new big bang, restarting the cycle of expansion and increasing entropy.

5. How does entropy relate to the concept of time in the big bang and big crunch?

Entropy is closely related to the concept of time in the big bang and big crunch. As entropy increases, time moves forward and the universe becomes more disordered. In a big crunch scenario, time would seemingly reverse as the universe collapses and becomes more ordered. However, the concept of time in these scenarios is still a subject of debate among scientists.

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