- #1
21joanna12
- 126
- 2
I'm looking at general relativity and particularly considering what happens at the Big Bang. I think the Friedman equation is [itex]H^2=\frac{8\pi G}{3}\rho[/itex] so I see that as the matter density goes to infinity, [itex]H[/itex] goes to infinity. According to this video (around 10:10), this is where the problem lies with GR's description of the Big Bang. The thing is I don't really get what the Hubble Parameter actually is, so I don't understand what the problem is with [itex]H[/itex] going to infinity. I know [itex]H[/itex] is [itex]\frac{\dot{a}}{a}[/itex], but I can't really find a description of what the scale factor is either. All I know is that it has something to do with the rate of expansion of the universe, although I don;t know how exactly they are linked.
Thank you in advance! :)
Thank you in advance! :)