Scientist are always saying that they can see back in time in terms of the light that has traveled from distant stars and galaxies. If we see light freom a star that is 1 billion light years away then it is said that that light is 1 billion years old therefore we can see 1 billion years ago. I dont get this concept. If we can see as far back as ten billion light years then how are we seeing this light? How did we as observers get to where we are in the ubiverse before the light that was created billions of years before the earth was even formed? We didnt travel faster than the light that we are seeing so how is this possible? Maybe I'm confused?
2006-09-06 01:18:30 · 9 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
If light was emitted 1 light year away it takes a year for that light to get to us...if it happen 10 billion light years away then it takes 10 billion years for us to see it, but the earth hasnt been here for ten billion years so how do we see it? That my question, How did we get in a position to see light that has been traveling for 10 billion years? Unless our planet has been here for that long..The universe is expanding did wee expand faster than that light to beat it and actually see it.. How do we see light that far back in time ?
2006-09-06 01:28:59 · update #1
Look at it like this:
An event occurs.
Light comes from that event, either it's emitted or reflected.
You, an observer, see that light, and thus observe the event, some time later. If you're right next to the object, that time is virtually nil, you see it instantaneously.
However, if you're a light year away from that event, it will take a year before you can see it. Thus, you're watching something that occurred 1 year back in time.
Now the farther away things are, the farther back in time you see, b/c it took so long for the light to arrive.
The flaky question is, what's happening NOW? We know things are out there, but what has been going on in their billions of years of history?
2006-09-06 01:25:11 · answer #1 · answered by Iridium190 5 · 0⤊ 0⤋
Yes, this can be confusing, but I will try to explain even though I am not a scientist. Light travels through space and time. Just like anything else, it takes time to travel from here to there. One light year is the distance light travels in a year. (don't know the actual mileage, but it is immense).
What we see when we look up at these stars is the light that they have emitted a possible 1 billion years ago. These stars are unimaginably far away, and the light has been traveling all that time.
it's a little difficult to explain without knowing off-hand the age of the Earth, but during all those years since that the light originally emitted from that far away star, things occur at this end of the universe, and by the time that light reaches us, what originally existed here has changed drastically.
This is the best I can do. Hope it helps
2006-09-06 08:39:15 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Light travels 186,000 miles per second or 6 trillion miles per year. It takes light 8 1/3 minutes to get to the earth from the sun. If the sun suddenly blew up we wouldn't know it for 8 1/3 minutes. Then there would be a flash and we'd all be gone.
If a supernova 10 million light years away blows up we don't see the light for 10 million years because it takes that long to get here. So when we finally see it it's like looking back in time 10 million years to when it actually blew up.
The furthest Hubble can see is about 13 billion light years away. So we're seeing stars and galaxies as they were forming 13 billion years ago, which is only 700 million years after the Big Bang.
2006-09-06 08:35:33 · answer #3 · answered by yadayada 2 · 0⤊ 0⤋
I think that there's a distinction between DISTANCE away and AGE of a star. We see light from distant galaxies and stars because they were formed billions of years ago. Light from these objects go in all directions. With the expanding universe, the light moves faster than the galaxy does so it 'overtakes' it's position in the universe and gives evidence to it's age by it's spectrum.
A star that is 10 billion years old doesn't necessarily mean that it's 10 billion light years away. That old starlight is coming to us extremely red-shifted (something that light does when it moves away from the viewer) and so we see it as it was in the past. Think of it as a 'trail' of light that has been left for us to see.
The Sun itself that we see right now, is how the sun looked 9 minutes ago. It takes that long for the light to reach us. Same idea for stars that are WAY out there.
excellent question
2006-09-06 08:26:48 · answer #4 · answered by words_smith_4u 6 · 0⤊ 0⤋
Say light from an object has travelled 10 billion light years. That means that we see the object as it was 10 billion years ago. That doesn't mean that at the time the light was emitted the object itself was 10 billion years old.
2006-09-06 08:30:52 · answer #5 · answered by Morgy 4 · 0⤊ 0⤋
the earth doesn't have to be here in order for the light to travel here. it's the same as saying there is no sunlight on a deserted island because there are no people to see it?
2006-09-07 09:38:55 · answer #6 · answered by ? 5 · 0⤊ 0⤋
to be frank.. they have been talking abt this concept since last 20 years.. but havent been able to make it practical... so i think theoretically it is possible but not practically... for humans atleast...
2006-09-06 08:27:12 · answer #7 · answered by Anonymous · 0⤊ 0⤋
i don't get your question
2006-09-06 09:00:07 · answer #8 · answered by shotgunsherriffs 3 · 0⤊ 0⤋
WHAT???
2006-09-06 08:25:14 · answer #9 · answered by Donny C 2 · 0⤊ 1⤋