Is the Expansion Rate Truly Accelerating?

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SUMMARY

The discussion centers on the concept of the accelerating expansion rate of the universe, specifically addressing how this affects the movement of distant celestial objects. Participants clarify that the acceleration refers to the rate of expansion itself, not merely the distance of objects from Earth. As a result, the time required for an object to move from 10 billion light years to 11 billion light years will indeed increase over time, reflecting the implications of an accelerating expansion rate.

PREREQUISITES
  • Understanding of cosmological principles, particularly the expansion of the universe.
  • Familiarity with the concept of redshift and its relation to distance and velocity.
  • Basic knowledge of the speed of light and its implications in cosmology.
  • Awareness of the implications of dark energy on cosmic expansion.
NEXT STEPS
  • Research the role of dark energy in the accelerating expansion of the universe.
  • Study the concept of redshift and its measurement in cosmology.
  • Explore the implications of the Friedmann equations on cosmic expansion.
  • Learn about observational evidence supporting the accelerating expansion, such as Type Ia supernovae data.
USEFUL FOR

Astronomers, astrophysicists, and students of cosmology who are interested in understanding the dynamics of the universe's expansion and its implications for distant celestial objects.

thetexan
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I'm studying about accelerating expansion rate.

I am reading that the rate of expansion is accelerating. Now the farther objects are from us the faster they are moving away from us due to expansion. Farther and farther, faster and faster. But that would occur even if the expansion rate is steady. Are they saying that the rate of the expansion itself it accelerating? And won't that mean that the time it takes for an object to move from say 10 billion light years to 11 billion light years from us will be longer now that say a billion years from now?

tex
 
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"the rate of expansion is accelerating" is not comparing different distances, it is comparing different times for the same object. If we consider an object where the distance increases by c/2 today, its distance will increase slightly faster tomorrow.
thetexan said:
And won't that mean that the time it takes for an object to move from say 10 billion light years to 11 billion light years from us will be longer now that say a billion years from now?
That is yet another comparison, because there we would track different objects.
 

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