> Basically, the hydrogen-helium abundance helps us to model the expansion rate of the early universe. If it had been faster, there would be more neutrons and more helium. If it had been slower, more of the free neutrons would have decayed before the deuterium stability point and there would be less helium.
> If it had been faster ...
> If it had been slower ...
Isn't the inflation conceived to be as fast and long as necessary so that inputs to baryogenesis give result with hydrogen to helium ratios that are in line with experimental data?
As I understand it, something like the big bang produces mostly light elements -- hydrogen and helium. Everything else is produced in the stellar fusion machine plus supernovas.
So, by the time that the heavier elements are forming, the big bang has been done with and forgotten about for at least, like a microsecond. ;-)
I was referring to creation of hydrogen, helium and traces of some others like lithium.
Thinking about what you said I think necessary condition to get big bang hydrogen/helium ratio is that although there must be very high energy density we must not have too much of gravitational confinement because that would spark fusion and mess up the ratio bringing to closer to what we have currently in the universe.
> Basically, the hydrogen-helium abundance helps us to model the expansion rate of the early universe. If it had been faster, there would be more neutrons and more helium. If it had been slower, more of the free neutrons would have decayed before the deuterium stability point and there would be less helium.