Nasa's new IR Telescope

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Posted:
in General Discussion edited January 2014
I saw on the BBC.co.uk website that NASA are launching an Infra-red telescope that they hope to be able see right back to the early universe.



I have a question, I cant quite get my head around



Its safe to say that the big bang theory is relatively well known and established.



Its a kind of difficult question to phrase, but why are we still able to see the light from the big-bang, After all, if its (light) taken 15 billion years to get to us, and we (Earth are 4 billion years old), at what point did we overtake the light?



Of course I know this is a stupid Question, and I dont think for 1 minute that we did overtake it, but imagining the blast from the big bang, the light would travel the furthest in any given time, and the mass less, radially from the centre. so when we look at where the event occured, we should see relatively little, like blackness. I know were not looking at the light thats already passed us as its moving away from us. Were not looking at the light at the far diameter of the blast radius, because that too is moving away from us. We seem to still be able too see light from the centre of the blast, and as light doesn't stay still, I dont really understand why we are still able to see it.



Hope that makes sense

Comments

  • Reply 1 of 8
    while not the answer to your specific question, some extra info may be found here and here



    and SIRTF is indeed a nifty new bird.
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  • Reply 2 of 8
    chu_bakkachu_bakka Posts: 1,793member
    Well... the best way to describe is... it takes millions of years for the light of stars that we can see with the naked eye to reach us... so the stars that you can see in the sky now... at this moment may not even exist any longer...



    So the further out you can see with these high powered eyes... the younger the star is... or was actually.



    I think I got that right.
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  • Reply 3 of 8
    Quote:

    Originally posted by chu_bakka

    Well... the best way to describe is... it takes millions of years for the light of stars that we can see with the naked eye to reach us... so the stars that you can see in the sky now... at this moment may not even exist any longer...



    So the further out you can see with these high powered eyes... the younger the star is... or was actually.



    I think I got that right.




    yes, but my point was, that I don't understand why we should still be able to see this specific light, after all, if it came from the same origin as us, it should have gone well past our scope of vision by now, and we should see a relative darkness in the centre of the blast.
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  • Reply 4 of 8
    chu_bakkachu_bakka Posts: 1,793member
    And my point is that we can't see even that far back...



    Plus if the universe is expanding we're moving away from the "center" all the time.
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  • Reply 5 of 8
    Quote:

    Originally posted by chu_bakka





    Plus if the universe is expanding we're moving away from the "center" all the time. [/B]



    Exactly, so why is there still light from this centre reaching us now?
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  • Reply 6 of 8
    x xx x Posts: 189member
    Quote:

    Originally posted by Anna Mated

    Its a kind of difficult question to phrase, but why are we still able to see the light from the big-bang



    Nevermind, thought you were talking about something else.
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  • Reply 7 of 8
    the first links i provided relate to cosmic background microwave as well as visible-spectrum light. some of the microwave anisotropy stuff is helping show the universe is still expanding, but at a decelerating rate, and some attempts to explain theoretical imbalances of energy level



    as for "big bang" light, no. we're not seeing that far back. star formation actually seems to be decreasing



    Quote:

    "Our analysis confirms that the age of star formation is drawing to a close", Heavens said in a statement. "The number of new stars being formed in the huge sample of galaxies we studied has been in decline for around 6 billion years."



    Similar results have come from studies involving more distant galaxies that are seen as they existed way back in time. Then and there, star formation was found to be far more prolific than in closer, more modern galaxies.




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  • Reply 8 of 8
    shetlineshetline Posts: 4,695member
    Quote:

    Originally posted by chu_bakka

    And my point is that we can't see even that far back...



    Plus if the universe is expanding we're moving away from the "center" all the time.




    Anywhere and everywhere is "center" of the Big Bang. You're at the center right now. You can't think about the big bang as if it were an event that happened out in the middle of some big empty space, expanding outward into a pre-existing emptiness. All of space itself was compressed into the tiny primordial point than was the beginning of our universe.



    These things are difficult to picture in your mind because you can't apply simple common-sense notions that stem from simple three-dimensional Euclidean geometry when you think about how the universe is shaped and how it's expanding.
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