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How do astronomers look at historic CMB?

  1. Dec 18, 2008 #1
    How do astronomers "look" at historic CMB?

    I have a few question regarding CMB (Cosmic Microwave Background):

    I am confused, when I look at this
    [​IMG]
    is this a 360 degree view or a normal one sided view?

    As recent study that shown the universe is flat, do astronomer did consider at which where the top and bottom side should laid when we are looking at CMB photo? I mean that the is "top and bottom" difference of our flat universe?

    And, how can we observed this historic CMB?
    [​IMG]
    I don't understand, thinking logically, since these radiation happened long time ago, how can we still can observed them? The easiest reason I can think about is that matters formed at far greater light speed expelled from big bang point and then re-observed the background radiation emitting of bid bang period. I know my idea here should be wrong, tell me whats really going on.
     
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  3. Dec 18, 2008 #2

    cristo

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    Re: How do astronomers "look" at historic CMB?

    It's an all-sky map; i.e. a three dimensional image projected into two dimensions. In order to recover the third dimension, imagine curling the edges of the picture out of the screen so as to make a ball with the picture on the inside. We are then at the centre of the inside of this ball.

    Firstly, you should note that we do not definitively know whether the universe is flat, open or closed. I think the predominant opinion is that the universe is flat, but a closed universe has not been ruled out. I'm not entirely sure what your second question is; has my previous comment, that the CMB map is a 3D image projected onto a 2D surface answered it?

    I think your problem here is that you are talking about the 'big bang point.' Presumably, by this you mean a "point from which the universe has expanded." If so, then it should be noted that such a point does/did not exist. There is no centre of the expansion, and thus the CMB was formed everywhere in space and the photons have been losing energy ever since.
     
  4. Dec 18, 2008 #3
    Re: How do astronomers "look" at historic CMB?


    cristo .. can you explain more about the interpretation of the word "flat" that is being referred to here ?

    I have a strong definition of the term flat to me as in geometry a 2 dimensional plane .. The flat plane being of zero scalar dimension .. same logic as how a geometric "point" has no size and a "line" has no width by definition .

    Yet , surely the Universe as we know it is not completely flat .. so i can only assume it is absurdo facto and that "flat" does not mean flat but means flattened ? .. or something like that ..

    cheers
     
  5. Dec 18, 2008 #4

    HallsofIvy

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    Re: How do astronomers "look" at historic CMB?

    "Flat" means 0 total curvature- the metric tensor for the universe can be diagonalized- and does NOT imply 2 dimensions.
     
  6. Dec 18, 2008 #5
    Re: How do astronomers "look" at historic CMB?

    Cool .. thank you , HallsofIvy


    So by Zero total curvature .. does this equate to zero apparent distortion ?

    i.e zero total curvature = zero measurement bias ?
     
  7. Dec 19, 2008 #6
    Re: How do astronomers "look" at historic CMB?

    You mean, is actually a cooling of initial radiation of universe and its not coming out from any point/radiation of source? Weird, how come its shooting all around... I thought it blasted AWAY from the Bang.
     
  8. Dec 19, 2008 #7

    marcus

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    Re: How do astronomers "look" at historic CMB?

    That's a common misconception about the standard Big Bang picture.
    Check out the Lineweaver Scientific American article. "Common Misconceptions about the B.B." Princeton uses it as reading material for their astro course. Link is in my sig.

    People generally get these misconceptions from popularization and also the misleading terminology. Fred Hoyle who made up the term Big Bang hated the idea and wanted to discredit it, he had a competing steady state model which was losing out. He did his worst by inventing a deceptive but catchy name that gives everybody the wrong mental picture. Journalists liked the sound of it---no turning back, it's in the language.

    At some stage everybody has to work to overcome endemic misconceptions. You aren't the only one. Reading Lineweaver's article will help, that's what it was intended for.

    there is no point of origin in space, so there is no "AWAY" directions

    all matter, throughout all space, was at one time the source of CMB for somebody. The CMB we are getting now happens to be from matter that is a certain definite distance away so the timing is right. If it was nearer the light would have been here and gone already. If it was farther the light wouldn't have gotten here yet. The matter we are getting CMB from today is located on what is called the "surface of last scattering"---a spherical surface of all the points a certain distance from here.

    If there are people living now out there at that distance, on our surface of last scattering, then our matter was source to some of the CMB that they are now getting. the emission of the CMB happened simultaneously all over the universe, throughout all space, at a given moment.

    if there is anything you don't understand, ask and keep on asking until you get it.
    But do have a look at the Lineweaver SciAm article.
    Also Einstein-online is good. Links to both are in my signature.
     
    Last edited: Dec 19, 2008
  9. Dec 19, 2008 #8
    Re: How do astronomers "look" at historic CMB?

    Howdy marcus ,

    Just read the Einstein Online page The shape of space .. was pleasantly surprised at its brevity and to be honest simplicity .. followed quickly through the Cosmic sound - curvature and the microwave background radiation page and enjoyed the rigor there even more ..

    Can you shed some insight into why the issue of this rather curious inquiry into the curvature of Space was ever taken seriously .

    The Einstein Online version refers that the readings taken from the CMB verify that Space is Flat .. which is no surprise to most of us i guess who seem to have no reason to suggest it was ever otherwise .. So why was it ever seriously considered to be a matter of contention .. is there some background to the issue - something that made people think it likely ?

    I have no problem with parallel universes .. orthogonal universes .. am quite happy to consider instantaneous communication , and a whole lot of other concepts that i find in many ways such productive places for the mind to dwell .. but i do not see any substance or significance to this Curvature of Space concept .
    So given apparently no reason for it to even be considered -
    Why was it ?
     
    Last edited: Dec 19, 2008
  10. Dec 19, 2008 #9
    Re: How do astronomers "look" at historic CMB?

    "Even astronomers frequently get it wrong"...
    **** this, I think there are A LOT of people being misunderstanding just like me. I felt myself funny that I thought scientist are wrong/blind at first and all of sudden what I found is actually a misunderstanding.:mad:

    Ok, since I make a point here. I am going to look around again about the origin universe creation model and related problems. By the way, it will be great full if anyone here can pass me some link.
     
  11. Dec 19, 2008 #10
    Re: How do astronomers "look" at historic CMB?

    These aren't mis-conceptions then but downright lies that are being forced onto the public psyche . Creating massive amounts of destructive confusion in minds purely for the purpose to deceive ..
    Do you think if it was a physical health matter not a mental health matter that it would be more acceptable ?

    Sort of like Richard Nixon in Physics on a grand scale ..

    And to admit defeat to a lie so readily shouldn't happen .

    Fact is that the philosophical comment is entirely relevant " a truth is never lost ,, its still there eternal - while all falsehoods are temporary and none too soon forgotten " .
     
  12. Dec 21, 2008 #11
    Re: How do astronomers "look" at historic CMB?

    OK , so here is George Snoot 14 min 30 sec in to his presentation saying " .. that the entire visible universe .. everything we can see in every direction with the hubble space telescope plus our other instruments was once in a region that was smaller than an atom .."

    So all the universes known visible matter vectors have ~point origin~ .. that is the hard science position right ??

    Goddamn it , why are you confusing the arguments Marcus ? -
     
  13. Dec 21, 2008 #12

    marcus

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    Re: How do astronomers "look" at historic CMB?

    I'm glad you watched the George Smoot TED talk. It's a great talk.
    Smoot's talk is consistent with Lineweaver's "Common Misconceptions" article in SciAm. Lineweaver is a bit more clear because it is written and in front of you with diagrams and he can take the time to spell out more detail and avoid ambiguity;

    So I would urge you to also read Lineweaver. He is also one of the short list of top worldclass cosmologists. Link's in my sig.

    See if you can find anything in Lineweaver that contradicts what I've been saying. (Though what I say is not the important thing, what matters is what he says.)

    I don't think Smoot says "point origin". I don't think he says there is a point in empty space---a point from which the visible universe expanded. Lineweaver for example takes the trouble to rule that out.

    I think Smoot says there was a moment of very high density. Smoot does not contradict the idea that the universe had infinite size at the moment of the big bang, he only says that the VISIBLE portion was concentrated at very high density.

    =================
    BTW if anyone wants to see where Smoot's illustrative "visible part of universe concentrated into less than atom-size region" comes from, here is a calculation. The matter in the visible piece of the universe (currently stuff out to 46 billion LY) is estimated at 10^70 joules, energy equiv. Two of us here just calculated that last week in some other thread.

    And the inverse of Planck density is hbar G^2/c^7.
    So all we need to do is multiply 10^70 joule by hbar G^2/c^7 and we will have the volume in cubic meters.
    Just paste this into Google and press return
    10^70 joule*hbar*G^2/c^7
    It will calculate the volume as a small fraction of a cubic meter.

    But to get the linear size we want the cube root of that so put this in:
    (10^70 joule*hbar*G^2/c^7)^(1/3)

    It will calculate the side of a cube with that volume, to be 3 x 10^-15 meter.

    That is 3 picometers. Closer to the size of the NUCLEUS of an atom than to the full size of an atom. But Smoot said "smaller" than the size of an atom, so no problem.

    In some modern bounce models the density can go up to roughly half Planck before the bounce occurs. In other models it only goes to a few percent Planck. Either of these cases would still be consistent with what Smoot said.

    But no "point origin". :smile:
    No big empty space with something exploding in it.
     
    Last edited: Dec 21, 2008
  14. Dec 21, 2008 #13

    cristo

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    Re: How do astronomers "look" at historic CMB?

    Exactly, Smoot never mentions a point origin of the the universe.

    That is indeed a great talk, marcus, thanks for the link!
     
  15. Dec 21, 2008 #14
    Re: How do astronomers "look" at historic CMB?

    Its not important point atom particle smaller than atom .. whatever ..

    The big bang universe then has a center location ,

    a co-ordinate position from which everything expanded out from

    yes or no ?
     
  16. Dec 21, 2008 #15

    marcus

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    Re: How do astronomers "look" at historic CMB?

    The answer is no. And Smoot did not say that. If he had said it he would be at odds with all his colleagues, they'd consider he had made a mistake.

    I've listened several times to the talk and agree with Cristo:
     
  17. Dec 21, 2008 #16
    Re: How do astronomers "look" at historic CMB?


    cheers .. have recorded the .wav sound bite transferred it into .mp3 and uploaded it to the yourlisten.com server ..

    please review and then respond ..


    http://yourlisten.com/channel/content/22763/George_Snoot_Re_pysics_Forum_position_on_origin_

    [​IMG]
     
    Last edited: Dec 21, 2008
  18. Dec 22, 2008 #17
    Re: How do astronomers "look" at historic CMB?

    As regards the Lineweaver article from Scientific American .. it doesnt explain squat about the Big-Bang .. here is what it says ...



    But then as if in some sort of subconscious bipolar balancing act it is written ..




    is isnt - it is .. it doesnt - it does ..

    and here is a real doozie ,



    "That we can identify.. that we can identify? .. that he can identify ..

    this is a far far different statement than "there was no center to the expansion" ..

    So, does physics claim

    1. there can be no center of the expansion ..
    or that
    2. they havent identified such a location yet ??

    .. and if the answer is (2) .. well , why the hell not .. why is it so difficult ?
     
  19. Dec 22, 2008 #18

    cristo

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    Re: How do astronomers "look" at historic CMB?

    I'm not sure there's much to respond to; he still says the same thing. What he's saying is that the observable universe once occupied a region smaller than that of an atom. Note that he is not saying that the entire universe once occupied such a region. His comment also agrees with the standard phrase that most people use to describe the big bang, namely 'the universe was once a lot smaller, hotter and denser than it is today, and the universe has expanded from such a state.'


    I'm just wondering whether English is not your first language. If not, I can somewhat see why you're confused. Note that in your third quotation, the second sentence begins with 'not.' That is, "It was not a bomb going off at a particular spot that we can identify as the center of the explosion."

    The standard view is that there is no centre of the universe, just as there is no centre of the expansion. It is a misconception to think of the big bang as an explosion, in any sense of the word, and I encourage you to try not to think in that way.

    Any more questions, just ask :smile:
     
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