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Observable universe

I know there is a limit on the size of the observable universe but does this mean we know that the universe is in fact at least this big?
Also, how do we know the universe is 13.7 billion years old?

Reply 1

teachercol

Observable means light form their has had time to reach us.

Age? Look up Hubble's law about the relationship between recession speed of galaxies and their distance.

Reply 2

Tomm1998

Hubbles constant is 42 miles / second / 3 million light years, this can be re-written as 22530/s/million light year which = 0.022530/s/light year divide this by the speed of light to get 7.51^-11. Now if you do the reciprocal you will get the age of the universe, so 1/7.51^-11 = 13.3 billion years old. This won't be exact because of the rounding.

Reply 3

littlepussycat

I suppose the maximum obsevervable universe is at the distance an object accelerating away from you in free space reaches light speed, due to Hubble acceleration, and appears to freeze in size and time at 13.7 BLY, according to Hubble's Constant. If Hubble's Constant is 72, then the observable universe is about 13.7 biliion light years in radius. That indicates 13.7 billion light years is NOT the age of the universe, and the universe age is either much smaller or infinite ?!!