Which statement is true about Redshift and the Hubble constant?

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SUMMARY

The correct statement regarding the Hubble constant and galaxy recession is A: "The apparent speed of recession of a galaxy is given by the product of the Hubble constant and the distance to the galaxy." Statement B is false as the further away a galaxy is, the higher its apparent speed of motion away from us. Statement C is also incorrect; the look-back time for a galaxy with a redshift of 5.37 is not accurately represented as 4.1 billion years. Statement D is false because space is expanding, meaning the distance between galaxies does not remain constant.

PREREQUISITES
  • Understanding of the Hubble constant and its implications in cosmology.
  • Familiarity with redshift and its significance in measuring cosmic distances.
  • Knowledge of look-back time and its calculation in astrophysics.
  • Basic concepts of the expanding universe theory.
NEXT STEPS
  • Research the Hubble constant and its role in cosmological models.
  • Learn how to calculate look-back time using redshift values with tools like Ned Wright's Javascript cosmology calculator.
  • Explore the implications of redshift on the understanding of galaxy motion and distance.
  • Study the concept of an expanding universe and its effects on cosmic structures.
USEFUL FOR

Astronomy students, astrophysicists, and anyone interested in understanding the dynamics of the universe and the implications of the Hubble constant on galaxy motion.

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Which statement is true?

A The apparent speed of recession of a galaxy is given by the product of the Hubble constant and the distance to the galaxy.

B The further away a galaxy is, the lower its apparent speed of motion away from us.

C A galaxy with a redshift of 5.37 is situated at a look-back time of 4.1 billion years.

D Space is expanding uniformly so that the distance between galaxies remains constant.
 
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Which statement(s) do you think is/are true and why?
 
I think statement A is true but I'm not 100% sure whether D is false and there is only one true statement.
 
Well, to rule out C you can have a look at Ned Wrights Javascript cosmology calculator to determine the lookback time. Just plug in 5.37 for the redhshift. The light travel time is the "lookback time".

http://www.astro.ucla.edu/~wright/CosmoCalc.html
 
Well, isn't it generally true that the farther a galaxy is from us, the faster it appears to be receding?
 
Yeah, I didn't think B or C were the answers.
I'm still stuck between whether A or D is the right answer and I really need help.
 
Does it make any sense for the distance between things to remain constant in an *expanding* universe?

When we say that a galaxy is moving away from us, what does that mean? Does it not mean that it is getting farther away with time?
 
Statement A is definitely correct.
 

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