If the hubble space telescope is seeing the early universe?
Noname asked:
Forgive my ignorance at this.
If the hubble space telescope is seeing the early universe from billions of light years away, is our galaxy traveling at almost the speed of light away from the point where big bang occurred?
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Forgive my ignorance at this.
If the hubble space telescope is seeing the early universe from billions of light years away, is our galaxy traveling at almost the speed of light away from the point where big bang occurred?
for example:
an explosion or a black hole was detected by hubble from around 14 billion light years away and our galaxy was already at this point(here). So we are seeing what is happening at 14 billion years ago at yet our galaxy must have came from that part where the explosion begins..
Sorry bout that, can’t explain further.
May 13th, 2009 at 7:28 am
We’re not moving that fast.
Here’s a scenario:
Man1 switches on lightbulb at Point A.
Man2 stands 1 “light minutes” away from Point A (call it Point B)
Man2 will observe the lightbulb switching on one minute after the event occurs
Man2 could be standing still, or moving away, or moving towards…. it wont matter… as long at PointB is one “light minute” away from PointA and PointB is where Man2 is, then Man2 will see the light one minute later
May 14th, 2009 at 12:28 pm
it’s not necessarily that our whole galaxy is traveling at the speed of light, but that the light from other galaxies 14 billion light-years away is reaching us (14 billion years later).
Remember that the other galaxies are traveling too! It’s not just that Galaxy A is racing away from galaxy B, but rather that Galaxies A and B are racing away *from each other*. We may be 14 billion light-years away from each other NOW, but neither galaxy is at the originating point in space, we’ve been blasted off in different directions, so it didn’t take 14 billion years to reach the current distance.
May 17th, 2009 at 10:48 pm
The galaxies of the universe are traveling away from each other much as raisin in a loaf of rising bread dough (except for galaxies in a local family group that may be converging as the Milky Way and Andromeda). Those galaxies farthest away are traveling at the greatest speed away from us (similar to fast and slow cars moving away in opposite directions from a toll booth). However, it requires almost infinite energy for matter to approach the speed of light and we and the distant galaxies are likely each traveling at somewhat near half the speed of light in opposite directions. Some of the light from our galaxies is reaching the distant galaxy as some of its light is reaching us and both streams of photons were emitted about 14 billion years ago and have traveled uninterrupted at the speed of light.
May 18th, 2009 at 10:24 am
You’re mistaken in that our galaxy is traveling at almost the speed of light away from the point where the big bang occurred. The big bang created space itself, so the big bang occurred everywhere; it’s just that “everywhere” is expanding, and was once very small compared to today. The dopler shift of the cosmic microwave background shows we are only moving 0.2% the speed of light with respect to the original big bang.
So any direction we look, we are still looking at the big bang; just different areas of it in earlier eras, since looking through space also means looking through time. But 14 billion years ago the universe was also very small; so for very large units, “light years” implies less actual distance than it does for today’s universe.
May 20th, 2009 at 9:40 pm
There is no “point where the Big Bang occurred”. The Big Bang occurred everywhere in our Universe.
The parts of the Universe that are distant from us are expanding away from us at very high speed. In fact, most of the Universe is expanding away from us faster than the speed of light, and is therefore “beyond our event horizon”.
From the point of view of those places, we are expanding away from them at very high speed. The situation is entirely symmetrical.
Furthermore, the situation is complicated by relativistic time contraction. From our point of view, time on those distant galaxies passes much more slowly than our time (and vice versa). So to us, those distant galaxies appear to evolve more slowly, and look younger. Similarly, we appear younger to them, and evolving slowly.
Surrounding us in all directions, 13.7 billion lightyears away, we see the Big Bang happening. The time dilation there is infinite (stopping the precise moment) and we cannot see beyond that surface, our “event horizon”. That surface is moving away from us at the speed of light. Of course if you could go 13.7 billion lightyears away in an instant (perhaps through a wormhole), you would find that at that location, everything “now” looks like the galaxies and stars that are near the Milky Way (having evolved for 13.7 billion years), and when you looked back in the direction of the Milky Way, you would see the matter that will go on to make up the Earth emerging from the Big Bang.
By the way, General Relativity does not forbid relative motions greater than the speed of light, as long as the two objects are sufficiently far apart that causality paradoxes are avoided.
May 23rd, 2009 at 2:54 pm
Well you are sort of correct — the Universe has been measured to be AT LEAST 156 billion light years wide– due to the expansion during the last 13.7 billion years–
Read this– for a good explanation–