Relativistic Effects on our Observations of the Universe

  • #1

Main Question or Discussion Point

While observing the Sun, which is 8 light-minutes 12 light-seconds away from us. We (by visible and invisible spectrum of the electromagnetic radiation) observe its state 8.20 minutes ago. Special relativity forbids any information to travel at speeds greater than that of light. This should apply to the information that a mass exists at a particular distance, which is mediated by gravitons. Thus, by all means, the information about Sun that we have is 8.2 minutes old.

If we apply this to Deneb, a star 1.4k light-years away from Earth, its state at a time 1.4k years will we see. Then to the M87 galaxy - 55 ± 1 Mly - its state at a time 55 ± 1M years ago.

How do we model the universe at present (for computations) when we have information that is older further the body away from us? More importantly, how can we compare two objects at different times?
 
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Answers and Replies

  • #2
Chronos
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Correct! EM radiation emitted by all objects in the universe are time delayed due to the finite speed of light. The computation process is, as you surmised, complicated - and further complicated by redshift.
 
  • #3
The computation process is, as you surmised, complicated - and further complicated by redshift.
I would like to have a basic idea of the concept. What would be the error graph when approximate data is extrapolated to such large values?

Maybe I'm thinking far ahead of my current knowledge (which I would rate as beginner), however, if the newly created matter is not accounted in this model, by any chance could our mysterious dark matter be what is created but cannot be observed because of the time delay, which, I could expect to get answer to even in my thread about https://www.physicsforums.com/showthread.php?p=2854997" , which I could relate to motion of the spin-2 and massless gravitons in "certain" conditions.
 
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  • #4
Janus
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I would like to have a basic idea of the concept. What would be the error graph when approximate data is extrapolated to such large values?

Maybe I'm thinking far ahead of my current knowledge (which I would rate as beginner), however, if the newly created matter is not accounted in this model, by any chance could our mysterious dark matter be what is created but cannot be observed because of the time delay, which, I could expect to get answer to even in my thread about https://www.physicsforums.com/showthread.php?p=2854997" , which I could relate to motion of the spin-2 and massless gravitons in "certain" conditions.

Exactly what "newly created matter" are you referring to?.

Even if we accepted the idea of such matter springing from nothing, we wouldn't see the effect it has on other objects any sooner than we would see it.
 
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