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I've been wondering about this thing.

The universe's radius is 46 gly. But a galaxy in 13.8 gly from us cannot be seen because it travels faster than the speed of light.

So is there a galaxy in, say, 30 billions light years away from us?

But before that, I'd like to know about this question below.

According to

https://en.wikipedia.org/wiki/Hubble's_law#Observed_values

Hubble constant is 67.6 km/s per mega parsec as of 13th July 2016 observed by https://en.wikipedia.org/wiki/Sloan_Digital_Sky_Survey

Wow, is it last week?

Now, what I want to know is this.

A. Is it true that a galaxy at ##300000/67.6 = 4437.87 mega parsec## or ##4437.87 * 3.26 = 14467## or 14.467 giga light years away from us travels almost at the speed of lightwrt us? Let's call itgalaxy A

B. Is it true that a galaxy at ####150000/67.6 = 2218.94 mega parsec## or ##2218.94 * 3.26 = 7233## or 7.233 giga light years away from us travels almost at 0.5cwrt us? Let's call itgalaxy B

3. Now relativity velocity addition would tell us that.

##v1=\frac{v3+v2}{1+v3.v2}## or

##v3=\frac{v2-v1}{v1.v2-1}##

Let

v1 = speed of galaxy A = 1wrt us

v2 = speed of galaxy B = 0.5wrt us

v3 = speed of galaxy Awrt galaxy B

Now if we put the number into equation.

##v3 = \frac{v2-v1}{v1.v2-1}##

##v3 = \frac{0.5-1}{0.5-1} = 1##

So? The speed of galaxy A wrt B is 1?

So, actually, because length is so contracted, then there's no galaxy at say 20 gly away from us? They are all compacted at around 14.4 giga light years away from us?

Thank you very much.

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# B Hubble flow and velocity addition

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