<p>While deriving the epoch of matter-radiation equality, we assume the transition from radiation dominated universe to matter dominated universe as instantaneous. But how instantaneous is this transition really?</p>

CC BY-SA 4.0
2020-07-18T14:59:17.737Z
But you don't make that assumption at all.
ProfRob
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2020-07-19T07:16:07.507Z
Are there any examples anywhere where somebody makes "use" of the instantaneousness? As far as I know, the transition times are only used to argue that simpler models leaving out non-dominant contents are decent fits sufficiently before and after the transition.
Anders Sandberg
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2020-07-20T09:22:19.150Z
Well, I found Andrew Liddle uses this assumption in his book "An Introduction to Modern Cosmology"- Second Edition, Ch-11. Quoting "We now have enough information to calculate the full temperature versus time relationship for the Universe, assuming an instantaneous transition between radiation domination and matter domination."
Arnab Chowdhury
<cosmology><radiation><matter>
Transition of Domination in the Universe
Arnab Chowdhury
# Transition of Domination in the Universe

(Asked by: username_0 on 2020-07-18)

While deriving the epoch of matter-radiation equality, we assume the transition from radiation dominated universe to matter dominated universe as instantaneous. But how instantaneous is this transition really?

**Tags:** cosmology, radiation, matter
> **Comments:**
> **username_1**: But you don't make that assumption at all.  
> **username_2**: Are there any examples anywhere where somebody makes "use" of the instantaneousness? As far as I know, the transition times are only used to argue that simpler models leaving out non-dominant contents are decent fits sufficiently before and after the transition.  
> **username_0**: Well, I found Andrew Liddle uses this assumption in his book "An Introduction to Modern Cosmology"- Second Edition, Ch-11. Quoting "We now have enough information to calculate the full temperature versus time relationship for the Universe, assuming an instantaneous transition between radiation domination and matter domination."  

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