The expanding universe and space?

[Gilded]

I think I'm becoming one of those people who read lots about quantum mechanics etc. and doesn't really understand the basics too well and goes around asking silly questions.

 

Anyway, zero point energy (of vacuum). If you assume that when the universe expands more space is created and a certain volume of space or vacuum contains a certain amount of ground state energy, then doesn't this increase the overall energy of the universe, seemingly "out of nowhere"?

[Martin]

I think I'm becoming one of those people who read lots about quantum mechanics etc. and doesn't really understand the basics too well and goes around asking silly questions.

 

Anyway' date=' zero point energy (of vacuum). If you assume that when the universe expands more space is created and a certain volume of space or vacuum contains a certain amount of ground state energy, then doesn't this increase the overall energy of the universe, seemingly "out of nowhere"?[/quote']

 

yes.

 

there is no global energy conservation law in the context of cosmology.

so the expansion of space does add to the total energy of the universe (according to the usual LambdaCDM model in cosmology) and this does not contradict any proven conservation law

 

BTW the dark energy density is approximately 0.6 joules per cubic kilometer

 

so if the universe at present has a finite spatial volume, the dark energy in it represents a certain finite amount of energy, and if the expansion then adds one cubic kilometer to the volume, this then adds 0.6 joules to the sum.

 

============================

 

the CMB has also LOST energy since the moment of recombination with the CMB photons were released. it has lost energy by the fact that each photon has been redshifted by a factor of 1100.

 

this has reduced the energy of each photon by a factor of 1100

 

so the CMB (cosmic microwave background) now has only 1/1100 of the energy that it originally did.

 

this energy has not gone anywhere (as far as cosmologists know) it has simply been eliminated

 

this does not violate a proven conservation law because in Gen Rel, which is the basis of cosmology, there is no proven global conservation of energy law.

 

this is very interesting and you have asked an extremely good question.

 

It just happens that the amount of energy lost by the CMB in the course of its history is roughly on the same order of magnitude as the extra energy produced by expansion, if space really contains the estimated dark energy.

This is purely coincidental AFAIK

 

sorry I cant say more about it

[GutZ]

I think I'm becoming one of those people who read lots about quantum mechanics etc. and doesn't really understand the basics too well and goes around asking silly questions.

 

That would be me! I will trumph your question so don't feel bad.

 

Is there a preferred energy to space ratio or balance in respects to cosmology?

[Martin]

That would be me! I will trump your question so don't feel bad.

 

Is there a preferred energy to space ratio or balance in respects to cosmology?

 

Someone else may answer differently depending on how they understand the idea of a "preferred" ratio.

 

I would say the answer is no, there is not.

 

If the cosmological constant Lambda is actually constant (as in the standard cosmology model it is)

 

And if it is legitimate to think of it as represented by a dark energy density (as a lot of people do assume it is.)

 

then the ratio of energy to space will keep on DECREASING indefinitely but it will be asymptotic. It will approach a limit. It wont decrease to zero. It will make a soft landing so to speak, at the level of about 0.6 joules per cubic kilometer

 

That is considering matter and energy of ALL KINDS and totaling it up as energy equivalent.

 

the thing is the universe is (according to the most common mainstream model called "Lambda-CDM") NOT supposed to stop expanding.

 

so every kind of matter and energy (except dark energy) THINS OUT MORE AND MORE until in hundreds of billions of years there is almost nothing, everything is all thinned out so much that space seems almost empty, EXCEPT for dark energy which has a constant density.

 

I dont like talking about the far far distant future because I think science has a history of making mistakes and is very likely to be wrong in these very longrange projections. So I dont worry about it.

 

but they do have this Lambda-CDM model that is widely accepted by working cosmologists at the moment---some people call it the "consensus" model or the "concordance" model because there is such a lot of agreement. and like it or not this model does make a longrange prediction (as well as more exciting things what I think are more interesting)

and this longrange prediction is (in my view) dismal and boring.

 

I dont advocate it, I just report.

 

maybe you could say that the endpoint limit that it approaches is a kind of "preferred" equilibrium but that seems sort of horrible to me, it is like saying the universe prefers emptiness----ugh, dont want to think about it