All Questions
5
questions
3
votes
1
answer
312
views
How to compute Coulomb scattering rate(in early universe)?
I want to compare Coulomb scattering rate with Hubble's expansion rate.
To compute Coulomb scattering rate, I know that
$$ \Gamma = n_p\sigma v_{rel} $$
Here, $\sigma = \frac{e^{4}}{(4\pi\...
- 624
1
vote
2
answers
180
views
Kolb and Turner's expresion for number density Eqn. (3.46) and pressure in Eqn. (3.48)
Having defined the phase space distribution function $f(\textbf{r},\textbf{p},t)$ in $\mu-$space, one can express the information that there are $N$ particles in the volume $V$ through the condition \...
- 26.8k
4
votes
1
answer
1k
views
Boltzmann equation in cosmology
I have a question about the Boltzmann equation in cosmology.
Im trying to understand how this can hold? Where does the logarithmic terms come from?
It is explained quite well here http://www.damtp....
- 41
10
votes
7
answers
2k
views
Mathematically possible vs physically probable outcomes
A good buddy of mine and I have had a friendly debate about the origins of the current state of our universe (namely; Earth and life on Earth) and have fundamentally disagreed in our stances with ...
- 201
13
votes
2
answers
580
views
Can $10^{23}$ stars be treated with methods of statistical mechanics?
Statistical mechanics is used to describe systems with large number of particles ~$10^{23}$.
The observable universe contains between $10^{22}$ to $10^{24}$ stars. Can we treat those many stars as a ...
- 17.1k