Le 22/11/2015 20:38, Phillip Helbig (undress to reply) a écrit :
If I go into a cafe and see three people more than 2 metres tall, I
would be surprised. If I surveyed all the people in a large country, I
wouldn't be.

Mr Helbig

At time t = 956 My after the supposed big bang, ALL galaxies are BABY
galaxies. They can't have more than 700-750My, if I follow SOME logic.

First stars can form only about 180My after the "bang" since we must
wait until the CMB drops around 50kelvins.

Yes, I know about statistics, but how can a galaxy in only 750My grow
from zero to TWICE the Milky Way???

Yes, if you measure the height of all babies in earth you are bound to
find exceptionally big babies but... what would you say if you found a
baby of 3.4m height???

Statistical fluke?

No, you would say: This is not a baby!

There are LIMITS imposed on the growth of galaxies by physical laws that
make galaxies of just 750My and that enormous size IMPOSSIBLE you see?

jacob

[[Mod. note -- Physical laws do indeed place limits on how fast galaxies
can form and grow. If we had solid and well-validated theoretical models
of galaxy formation/growth we could probably compute those limits.

But I don't think we have this level of understanding (yet). We sort
understand the main ingredients that go into galaxy formation/growth,
but I don't think we know all the parameters (density? temperature?
pressure? chemical composition? magnetic fields? turbulence? ambient
generation-I stellar population environment?) well enough to put
reliable limits on just how fast/slow formation and growth occur.
Nor do we have good observational data (yet) on very young galaxies
to help constrain these theoretical models.

So how do we know that 750 My isn't enough time?
-- jt]]