Information lost at the Big Crunch?

[Suekdccia]

TL;DR Summary

Would it be possible to truly erase information if the Big Bang ended in a Big Crunch?

Let's imagine for a moment that the universe stopped expanding somehow (even though the evidence we have suggests this is not going to happen) and gravity made it contract until reaching a Big Crunch state.

According to our actual understanding of physics and our current working models, Is it possible that the information about the universe (the information about its physical states and laws of physics) is lost at the Big Crunch? In what conditions at the Big Crunch would the information be "erased" and in what conditions it may survive? For example, if the entropy or the density st the Big Crunch is too big, information would be lost?...

 

[anorlunda]

What definition of information are you using? Without a physical definition, the question can't be answered.

Try reading this PF Insights article first. Pay close attention to the difference between information and knowledge, because almost all confusion in this topic results from loose definitions of information.

https://www.physicsforums.com/insights/how-to-better-define-information-in-physics/

For example, we think the universe is electrically neutral. The number of positive charges equals the number of negative charges. That's information. If the universe is still neutral after a crunch, isn't that conserving that information?

 

[Suekdccia]

What definition of information are you using? Without a physical definition, the question can't be answered.

Try reading this PF Insights article first. Pay close attention to the difference between information and knowledge, because almost all confusion in this topic results from loose definitions of information.

https://www.physicsforums.com/insights/how-to-better-define-information-in-physics/

For example, we think the universe is electrically neutral. The number of positive charges equals the number of negative charges. That's information. If the universe is still neutral after a crunch, isn't that conserving that information?

I basically asked this question after reading a couple of authors describing John Wheeler's idea of Mutability [1] where he basically defended a Big Crunch-Big Bang oscillatory model where all the laws of physics (even the most fundamental ones) would change between cycles.

These authors (Clement Vidal [2] and Paul Davies [3]) describe that this is possible if the Big Crunch is such an extreme event that would reprocess all the information of the universe and would therefore change the physical laws of the universe. They seem to refer to information as entropy but I am not sure.

Therefore I am asking: What would be necessary to happen at the Big Crunch to erase all the information about the physical states of the universe? What conditions would be necessary to eliminated that information and reshape the laws of physics?

[1]: https://doi.org/10.1007/978-94-010-2602-4_9

[2]: https://books.google.com/books?id=6... assume that the densities" "wheeler"&f=false

[3]: https://books.google.com/books?id=W...reme physical state that information"&f=false

 

[PeterDonis]

What would be necessary to happen at the Big Crunch to erase all the information about the physical states of the universe? What conditions would be necessary to eliminated that information and reshape the laws of physics?

These questions are unanswerable because the whole idea you refer to is speculative and is not based on any existing theory of physics. Which means the answer is purely a matter of opinion. That is off topic in this forum.

Thread closed.