Shouldn't we see faster expansion without dark energy

[KeplerJunior]

I understand that before we knew about dark energy we thought expansion would have slowed down since the big bang but we then discovered the universes expansion rate to be accelerating.

My question is, surely if the universe did expand faster at the big bang we would see it expand faster the further away we looked as you account for the limited speed of light so there would be no need for dark energy (ignoring missing mass etc.)

I'm sure I've missed something or got something wrong and that there is an explanation but i just wanted it to be clarified

 

[mathman]

You are confusing the rate of expansion with the velocity of far away galaxies. The rate was thought to slow down because of gravity, but it was found to be speeding up.

http://en.wikipedia.org/wiki/Accelerating_universe

 

[Drakkith]

Kepler, I *think* you are semi-correct. I believe when we looked out and measured lots of supernovas it turned out that galaxies closer to us were moving away faster than they should have been if the expansion had been slowing. Someone correct me if I'm wrong.

 

[KeplerJunior]

So the velocity of galaxies does increase the further away you look but that's not due to dark energy

 

[Drakkith]

So the velocity of galaxies does increase the further away you look but that's not due to dark energy

The expansion rate itself is what causes galaxies further away to have a higher velocity. The acceleration is actually an increase in the rate of expansion. I'm not sure if "acceleration" is the correct term for a rate of something. The rate is increasing over time, which we call acceleration.

 

[KeplerJunior]

Thanks so just that I'm clear galaxies having a higher velocity is just caused by the expansion of the universe the acceleration of the rate of expansion is not connected to that

 

[Drakkith]

Thanks so just that I'm clear galaxies having a higher velocity is just caused by the expansion of the universe the acceleration of the rate of expansion is not connected to that

Galaxies further away in distance having a higher velocity than those closer in distance is the result of expansion, yes.