Calculating Galaxy Distance for Light Speed using Hubble's Law

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    Hubble's law Law
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Discussion Overview

The discussion centers around calculating the distance to a galaxy where its recessional velocity equals the speed of light, using Hubble's Law. Participants explore the implications of this calculation and seek clarification on the necessary steps involved.

Discussion Character

  • Technical explanation, Mathematical reasoning, Debate/contested

Main Points Raised

  • One participant states that Hubble's Law can be used to determine the distance at which a galaxy's recessional velocity exceeds the speed of light.
  • Another participant seeks clarification on the specific distance required for a galaxy's recessional velocity to equal the speed of light.
  • A third participant reiterates the equation of Hubble's Law and suggests substituting the speed of light for the recessional velocity to solve for distance.

Areas of Agreement / Disagreement

Participants generally agree on the application of Hubble's Law to find the distance related to recessional velocity, but there is no consensus on the specific calculations or implications of reaching the speed of light.

Contextual Notes

The discussion does not resolve the mathematical steps required to calculate the distance, and assumptions regarding the values of Hubble's constant and the implications of recessional speeds approaching light speed remain unaddressed.

Einstein's Cat
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The recessional velocity of a galaxy can be calculated using Hubble's Law; the equation where Hubble's constant multiplied by the distance to the galaxy equals the recessional speed of that galaxy. Thus, what is the distance to a galaxy that is required so that the recessional velocity of that galaxy would be the speed of light. Any help would be very much appreciated and please correct any mistakes. Thank you.
 
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What do you need help with?
Hubble's law can be used to work out the kind of distance where the recession is faster than light - yes.
 
Simon Bridge said:
What do you need help with?
Hubble's law can be used to work out the kind of distance where the recession is faster than light - yes.
What I was asking is that what is the required distance so that the recessional velocity of the Galaxy would be exactally the speed of light?
 
But you know that - you wrote it down: v = Hd where H is the Hubble constant, d is the distance to the galaxy, and v is the recession speed.
So put v=c and use algebra to solve for d.
 

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