Age of Universe: Dist. to Big Bang vs New Star

[Gonçalo]

Question

When astronomers find a new star, say 15 billion light years away, why do they immediately relate that distance with the age of the Universe (the distance to the Big Bang point)?

--->cause if the Universe were like a balloon, and the Earth and the star were in the the surface of that ballon, their distance could be much bigger than the distance of the Earth to the Big Bang point!...

 

[MathematicalPhysicist]

Originally posted by Gonçalo
Question

When astronomers find a new star, say 15 billion light years away, why do they immediately relate that distance with the age of the Universe (the distance to the Big Bang point)?

--->cause if the Universe were like a balloon, and the Earth and the star were in the the surface of that ballon, their distance could be much bigger than the distance of the Earth to the Big Bang point!...

if the big bang were let's say around 20 billion years (im considering a time frame which is longer than the star's life span) (which is not but for the sake of the argument it is) old then the distance between the Earth and the big bang would be bigger than the 15 year old star.

 

[Sariaht]

Originally posted by loop quantum gravity
if the big bang were let's say around 20 billion years (im considering a time frame which is longer than the star's life span) (which is not but for the sake of the argument it is) old then the distance between the Earth and the big bang would be bigger than the 15 year old star.

If the 15 year old star was, oh, let's say markoolio, would that make any difference?

Will he burn stronger than any other star?

 

[MathematicalPhysicist]

sorry it's should be 15 billion year old star.

 

[polarstarus]

Actually the whole universe is only about 13.2 billion years old so no star is that old.

 

[Phobos]

There is no distance in space "to the Big Bang point". The Big Bang occurred simultaneously at every point in the universe. It was not an explosion of stuff into the void, it was (in part) the creation & rapid expansion of space itself.

When astronomers see a distant object (e.g., billions of light years away) they relate it to the age of the universe (currently calculated to be 13.7 billion years plus or minus a bit) because the speed of light is finite, and as such, the further away we look, the older the image we see. Since the Big Bang occurred 13.7 billion years ago, we cannot see anything further than 13.7 billion light years away because light from parts of the universe more distant than that has not reached us yet.

And since the Big Bang was the beginning of the entire universe, nothing in the universe can be older than that. (at least, the "visible universe"..i.e., the stuff within our 13.7 billion mile viewing range)

For more info, post questions to the regular forum...
https://www.physicsforums.com/forumdisplay.php?s=&daysprune=&forumid=71