QuestionExploring the Hubble Constant: Calculating Distance and Limitations

AI Thread Summary
The discussion revolves around calculating the distance to a galaxy receding at the speed of light using a Hubble constant value of 65 km/s/Mpc. The calculation attempts to convert units and apply the formula v = Hd, resulting in a distance of approximately 46,000 Mpc. However, a calculation error is noted, as the final result does not match the expected outcome. The conversation highlights the significance of this distance, especially considering the implications of the galaxy's recession velocity being equal to the speed of light. Questions are raised about the possibility of observing galaxies beyond this calculated distance.
_Mayday_
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The Question

One possible value for the Hubble constant is 65Kms Mpc. Calculate in Mpc, the distance from Earth for agalaxy trallening at the speed of light, 3.0\times10^{8}

Attempt

v=Hd

v=3\times10^8

H= 65Km s Mpc

First I will convert the constant to ms so that I have both in S.I. units.

v=3\times10^8 ms

H= 6.5 \times10^4 ms Mpc

Now I will just plug these values in!

\frac{3\times10^8}{6.5 \times10^4} = 4.6\times10^4 Mpc

Question
State what this distance represents.

Answer

This is the distance the galaxy is away from earth?

_Mayday_
 
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Sorry, is this poorly set out? Is there something I have not included?
 
You've made a slip in the final calculation (3x10^8)/(6.4x10^4) is not 4.6x10^4, that aside your method is correct.

The significance of your answer is more than just the distance to a galaxy in this case because the recession velocity is the speed of light.

Could the recession velocity be higher than this?
Could we see any galaxies beyond this one?
 
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