I Influence of Dark Energy and curvature in photon-baryon fluid?

[DoobleD]

When I read explanations about the early Universe and the oscillations of the photon-baryon fluid before recombination, effects of the cosmological constant and of the curvature of the Universe on the fluid are never discussed. Only dark matter, baryons, and photons are mentionned.

Dark energy and curvature have no impact on the fluid ?

I'm just looking for a simple answer, with at most some qualitative explanation if someone has that. The maths involved in the baryon-photon fluid oscillations are quite hard to tackle for me.

 

[mfb]

If dark energy is the cosmological constant, it is completely negligible in the early universe.

 

[PeterDonis]

Dark energy and curvature have no impact on the fluid ?

As @mfb said, dark energy is negligible in the early universe; the reason is that its energy density is so small. The energy density of dark energy is constant as the universe expands, so it was the same in the early universe as it is now; but the energy density of baryons and photons was much, much larger.

By "curvature", do you mean spatial curvature? If so, it is zero in our current best fit model; that's why it doesn't appear in the explanations you are reading.

 

[DoobleD]

Thanks for the answers.

 

[kimbyd]

Furthermore, if dark energy is not a cosmological constant, it still has to be negligible in the early universe. Otherwise it would disrupt Big Bang Nucleosynthesis, leading to a different mix of light elements in the early universe.