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Looking into the past with telescopes

  1. May 8, 2010 #1
    If it were possible to build a telescope that could see light from ~14 billion lightyears, would we be able to observe the Big Bang?

    And if so, would this be the case irrespective of the direction the telescope is pointing?
     
  2. jcsd
  3. May 8, 2010 #2

    phyzguy

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    It IS possible, and we DO see the big bang. But because of the expansion of the universe, the light of the big bang is red-shifted all the way into the microwave region of the electromagnetic spectrum. It is called the CMB (Cosmic Microwave Background) and was discovered by Penzias and Wilson in the 1960's And yes, we say basically the same radiation no matter which direction we look.
     
  4. May 8, 2010 #3

    D H

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    Close, but not quite right.

    The CMBR is not light from the big bang. It is light from a few hundred thousand years (400,000 IIRC) after the big bang. We can't see older than that because for the first 400,000 years the universe was opaque.

    There are slight, very slight, variations in the CMBR. Those slight variations give us some insight into what happened before the universe became transparent. You have probably seen bad science in movies where people use infrared scanners to see people moving around inside a house. That is bad science (houses have insulation), but there are inklings of good science there. We can see through walls with IR, but things are more than a bit fuzzy. Similarly, scientists can see a bit beyond the surface of last scattering thanks to the not quite uniformness of the CMBR.
     
  5. May 8, 2010 #4

    phyzguy

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    Like many of the posts here, I find this simply too pedantic for someone trying to understand these issues for the first time. Suppose someone saw a flash of light from an explosion and asked, "Was that light from the explosion?", would you answer:

    (1) Yes, that flash was from the explosion.

    or

    (2) No, you can't see the explosion because the initial density of the expanding plasma is so high that the plasma is opaque so that you can't see the actual explosion. All you are seeing is the light that is emitted after the initial fireball of the explosion has expanded and cooled to the point where the light can escape from the expanding fireball.

    While the second answer is technically more accurate, and is the answer you should give to someone who is studying these things in detail, I think it only serves to confuse people who are trying to understand things at a basic level. The CMBR is the light from the big bang, just like the light you see from a firecracker is the light emitted by the firecracker, or the light emitted by a lightning bolt is the light emitted by the lightning bolt.
     
  6. May 10, 2010 #5
    You can't see the CMBR in an ordinary telescope - you need a radio telescope for that - or a TV. Tune it somewhere between the channels and some of the hiss, static and crackle will be the CMBR. At least that's what I've read.
    The Big Bang is not a great name for it, iit was coined by a fellow who was trying to make fun of the concept (Hoyle?) It was very small considering the size it is and the size it will be. As for making a bang, well if a tree falls in a forest and no one is around does it make a sound? In the early stages of its development the universe was opaque or 'foggy' even if you could see it, there would be nothing to see. It took around 400,000 years for this to clear. So the answer to your question is simply: No. Not even with the best optical scope.
     
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