How is universe 13 billion yr old and farthest light is 13 billion light yrs away?

2010-10-07 8:12 pm
Light from farthest star is 13 billion yrs old as it traveled that distance. that star surely took 100x that time to actually travel to that spot. so the universe should be 100 X 13 billion yrs old. How is this not so?

回答 (8)

2010-10-07 8:42 pm
✔ 最佳答案
I understand your question and it is still hard for me to wrap my head around it. Here is a couple entries I found:

"The object you mention was only 4 billion (not 13 billion) light years from us when it emitted the light we see 13 billion years later. We and the object are separating from each other (not flying together) at about 1.8 times the speed of light. Although this appears to break the speed-limit law, it doesn't. "

So this is how we can see an object that is only 1 billion years old, 13 billion years later.

"This is the problem of defining a distance in an expanding universe: Two galaxies are near to each other when the universe is only 1 billion years old. The first galaxy emits a pulse of light. The second galaxy does not receive the pulse until the universe is 14 billion years old. By this time, the galaxies are separated by about 26 billion light years; the pulse of light has been traveling for 13 billion years; and the view the people receive in the second galaxy is an image of the first galaxy when it was only 1 billion years old and when it was only about 2 billion light years away. "

check the source links below, there are some good pictures that may help.
2016-06-03 3:31 pm
The universe is a finite entity,it has a beginning and an end. Everything started in the same place. A galaxy 1 billion light years away had to go there,developing,then it's light had to come back for 1 billion years. The Hubble deep field pictures show galaxies 13.5 billion light years away. These galaxies don't exist now. A galaxy is an end stage in the evolution of the universe,as they develop a galactic center,space is processed such that a red shift is generated. If this red shift is interpreted incorrectly it would indicate a universe much bigger and older than it is. The milky way is a good example. The galactic center is not inhabited by a black hole,it is driven by some sort of neutron star activity. If you could view our galaxy from any direction,you would observe a red shift indicating it was accelerating away. This would be the same for an observer on either side. This would explain why the outer arms rotate locked in step with the galactic center. It would also explain why dark matter is not needed to stop the arms from flying off. The universe is not a chaotic entity but it would be if it had no limit to it's size. A chaotic universe could not even come to an end.
2010-10-07 9:21 pm
actually the only reason we say the universe is 13 billion years old is because the oldest light to have reached us took thirteen billion years to get here, but space itself is moving out faster than stars which make it possible to suppose that there are stars farther away from us that we will never see because the light is beng pushed back by the expansion of space faster than the distnce it is actually travelling

i understand if its a difficult proccess to wrap your head around
參考: history channel
2010-10-07 9:04 pm
Well the star that is 13 billion light years away doesnt really exist we are just seeing it's image, we are looking into it's past. 100x? Where did you get that number!!
2010-10-07 8:34 pm
The star 13bil/lyrs away from us is a look into the past. That star doesn't even exist "now" really, only the light traveling from it does.

You would assume that would have to be one of the first stars to have formed.

Either way, all calculations of when the universe started its expansion phase...are estimations.
2010-10-07 8:25 pm
13 billion light years away? x100? Err ... No.
2010-10-07 8:20 pm
Where do you get the idea that the star took 100 x 13 billion years (or any time) to travel to that spot? The first stars formed a few million years after the big bang. The light from them started toward us right away. At that time, the distance from the star to us was pretty short. But as the light traveled, the space between the star and us expanded (something like going down an up escalator). After 13 billion years, the light finally got to us.
2010-10-07 8:15 pm
You have to remember that light didn't exist until well after the Big Bang.

And, the farthest stars are moving away from us at speeds approaching the speed of light (up to 99%).


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