RE: Is the universe infinite?
November 17, 2014 at 4:10 pm
(This post was last modified: November 17, 2014 at 4:16 pm by Alex K.)
Hi!
First of all, it is not known whether the universe is spatially finite or infinite. Temporally, the matter is unclear as the mechanisms behind the early big bang such as inflation are not tested well enough.
The quoted statements about entropy sounds like standard statistical mechanics. However, I would like to point out that the second law is a law only on average and for a large number of degrees of freedom involved. Its violation is merely extremely improbable, and as the number of involved degrees of freedom such as particles tends to infinity, the probability tends to zero. It could be violated statistically, for example if you have a box full of gas, and by accident all molecules randomly flying about gather in one half of it. This can in principle happen and corresponds to a strong decrease in entropy. The probability is 1/2 for one particle, 1/4 for two, 1/1024 for ten, and you can guess what it is for one mole of gas with 10^23 molecules. Still, it is merely extremely unlikely, not absolutely forbidden that entropy suddenly decreases like this.
Another matter is the embedding of all that in an expanding or contracting spacetime - then, things are not so obvious any more.
So I'd answer your fourth question in the affirmative, but I don't think a balance needs to be strictly kept.
I don't quite understand how you conclude that the universe is infinite.
Btw, why don't you write an intro post!
First of all, it is not known whether the universe is spatially finite or infinite. Temporally, the matter is unclear as the mechanisms behind the early big bang such as inflation are not tested well enough.
The quoted statements about entropy sounds like standard statistical mechanics. However, I would like to point out that the second law is a law only on average and for a large number of degrees of freedom involved. Its violation is merely extremely improbable, and as the number of involved degrees of freedom such as particles tends to infinity, the probability tends to zero. It could be violated statistically, for example if you have a box full of gas, and by accident all molecules randomly flying about gather in one half of it. This can in principle happen and corresponds to a strong decrease in entropy. The probability is 1/2 for one particle, 1/4 for two, 1/1024 for ten, and you can guess what it is for one mole of gas with 10^23 molecules. Still, it is merely extremely unlikely, not absolutely forbidden that entropy suddenly decreases like this.
Another matter is the embedding of all that in an expanding or contracting spacetime - then, things are not so obvious any more.
So I'd answer your fourth question in the affirmative, but I don't think a balance needs to be strictly kept.
I don't quite understand how you conclude that the universe is infinite.
Btw, why don't you write an intro post!
The fool hath said in his heart, There is a God. They are corrupt, they have done abominable works, there is none that doeth good.
Psalm 14, KJV revised edition
