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

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Physicists use redshift measurements to conclude that most galaxies are moving away from our galaxy, indicating that the universe is expanding. The discussion highlights the confusion surrounding redshift, with some questioning why redshift is observed universally rather than a mix of redshift and blueshift. It is clarified that while galaxies like Andromeda are blueshifted due to their proximity, the majority of distant galaxies exhibit redshift due to the universe's expansion. The concept of an expanding universe is explained as the movement of objects away from each other, which can occur even in an infinite universe. The conversation also touches on the nature of the observable versus unobservable universe, emphasizing that causality may not apply uniformly across these regions.
  • #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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