/sci/ - Science & Math

[Anonymous No.15842928]

If time dilation is real, then how would the universe have began 13.8 or 26.7 billion years ago? Wouldn't it have began at different times according to different observers?

[Anonymous No.15842947]

No idea. I'm still stuck on relativity. If observations of an event are made from two different star systems it makes sense that they would see the event at different times, and knowing the distance between those star systems and the years between observations (and the speed of light) should allow you to triangulate the position and actual year that this event happened at. Time dilation effects should complicate these calculations, but physics states that the position and time of this event are not reconcilable between the two star systems. Why not?

[Anonymous No.15843019]

What makes you think they didn't account for that when that calculation was made?

[Anonymous No.15843105]

yes you are completely correct, however galaxies and large structures are not moving very fast compared to the speed of light, so the differences are very small

[Anonymous No.15843217]

>>15842928
>Wouldn't it have began at different times according to different observers?
Time dilation as you learn it in special relativity is about proper times of a moving object being shorter than the naive coordinate time associated to an observer's frame. The proper time is physical and doesn't depend on observer.

In general relativity you pretty much never use this naive frame dependent time, so there is never an issue. The calculation of the age of the universe is looking at the proper time (the physical time) along a worldline that is passively moving with the expansion.

[El Arcón No.15843240]

Cosmology requires that use its models in the intended context. There still aren't any answers to the big picture mysteries.