How do physicists use redshift to determine the expansion of the universe?

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SUMMARY

Physicists utilize redshift to determine the expansion of the universe, concluding that most galaxies are moving away from the Milky Way, indicating universal expansion. The Doppler effect is significant only when observing galaxies that are not gravitationally bound to us, such as the Andromeda galaxy, which is currently blueshifted. The discussion clarifies that the universe can be infinite while still expanding, as expansion refers to the relative movement of galaxies rather than a physical expansion into pre-existing space. The observable universe is finite, limited by the speed of light, yet the nature of the unobservable universe remains a topic of debate.

PREREQUISITES
  • Understanding of redshift and its implications in cosmology
  • Familiarity with the Doppler effect in astrophysics
  • Knowledge of the Hubble constant and its significance in measuring cosmic expansion
  • Basic concepts of the observable versus unobservable universe
NEXT STEPS
  • Research the implications of the Hubble constant on cosmic expansion rates
  • Explore the concept of redshift in relation to different types of galaxies
  • Study the differences between observable and unobservable universe theories
  • Investigate the role of gravitational binding in galaxy movement and redshift
USEFUL FOR

Astronomers, cosmologists, physics students, and anyone interested in understanding the dynamics of the universe's expansion and the implications of redshift in astrophysical observations.

  • #31
But, is there such thing as infinite in physics?
 
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  • #32
Arifz said:
But, is there such thing as infinite in physics?

only one thing is infinite, that is universe...the emptiness

physics is to deal with singularities like matter energy stuff like that which spawned out of nowhere in the emptiness

Bigger picture of universe go beyond physics
 
  • #34

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