Question

An astrophysics question....

Answer 1

The scale factor a(t) describes the expansion of the Universe.
By considering how the redshift of light depends on the scale factor,
calculate how the present-day physical separation of galaxies com-
pares with their separation when light left galaxies we see today at
redshift 1?

Answer 2

Any help would be really appreciated! :)

Answer 3

well since light always travells at c then if we know how far away the galaxies were when the light we have just recieved we ejected the we can calcutale the time elapsed as x/c. therefore (x/c)a will correspond to the expansion of the universe in that time. we can therefore work out if we know the distance between two galaxies. (probably could be calculated using a little trig and our distance from the teo galaxies)we can work out by what that distance has increased. if we let y= the distane between two galaxies then y1=(x/c)ay. this could be extended to the seperation of all the galaxies in question. (i think... my astrophysics is not hat great)

i have no idea how much sense that makes but at least i tried.