question about origin of universe

Discussion in 'Astronomy, Exobiology, & Cosmology' started by psycha, Nov 29, 2007.

  1. psycha Registered Member

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    How come scientist say that when you look at background radiation, or at galaxies forming at the edge of the universe ,then you are looking at the beginnng of the big bang. They say the light from these formations has taken 14 billion years to get here and thus are the beginning of the big bang.

    But there seems to be a paradox. The big bang came from a singularity. The universe now is anything but a singularity, so whatever we see at the edge of the universe right now, happend much later than the initial moments of the big bang. If you are looking at the edge of the universe then how can you be looking at the distant past? The background radiation that we detect is coming from the edge of the universe inwards, not from the center of the universe outwards.

    Or is it that the universe is expanding, or did expand, at a rate close to the speed of light, such that any traveling light has to travel an even longer distance at every moment that passes by?

    Just a curious retard here.
     
  2. spidergoat alien lie form Valued Senior Member

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    The light is not coming from the exact beginning of the big bang, but from somewhat afterwards.
     
  3. James R Just this guy, you know? Administrator

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    The big bang happened everywhere at once, then things moved apart. Light from the furthest objects away from us now is only now reaching us, just as the big-bang light from our location is only now reaching objects on the edge of our visible universe.

    The universe has no centre.

    That is correct.
     
  4. ranthi Registered Member

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    I would think that the light we are witnessing as being 14 billion years old is far younger than what the universe currently is. how can they say that the age is 14 billion years old? Thinking this through a bit....timelineing it...assume the earth is at the center of the big bang..just for explanatory purposes

    1 second - all matter is coelesed (sp?)..no light to be viewed
    2 seconds - all matter is exploded 1 light second away..(so are we viewing the light from the first second or the second)?
    3 seconds - 2 light second expansion...(are we viewing from 1 second still or is it at 2 seconds or even 3..and are we taking redshift into account yet?)

    my question is this I guess. since scientists say that the universe is 14 billion years old, does that mean the light they are viewing is from half that distance?
     
  5. ranthi Registered Member

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    James R. - only thing I cant agree with is the Universe has no center. and since it cant be proven with today's technology..I might be free to hypothesize on this.

    I am of the firm belief that if it has a beginning, it has an end. alpha and omega, etc and etc. If the universe is expanding, it has to have had a point to expand from. This might be close minded..but it just makes sense.

    1. we have found no evidence of the big bang with our current level of telescopes. this either means that we are the center or the universe is possibly far larger and older than we suspect.

    2. the differences in temperature of the CMB suggest expansion...and it had to have a point to expand from somewhere.

    Personally, I dont think we will find the center in my lifetime..perhaps a theoretical center..but if it was an "explosion" large enough to give birth to the universe then I doubth there would be much evidence left at the scene of the crime.
     
  6. James R Just this guy, you know? Administrator

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    ranthi:

    Have you heard the balloon analogy?

    Consider the surface of a balloon to represent the universe. Dots are drawn on the surface to represent galaxies. Now, blow up the balloon. Every dot moves away from every other dot.

    The important point about this analogy is to keep in mind that it is only the 2-dimensional surface of the balloon that represents the universe - the centre of the 3-dimensional balloon is not part of the universe. In other words, a person living in the balloon universe could not point towards the centre of the balloon - he or she can only point along the surface; there is no "up" and "down" in balloonworld.

    To make the analogy apply to out universe, you have to take things up a dimension. In our case, we may live on a hypersurface of some complicated 4-dimensional shape. In our 3-d universe we cannot point towards the 4-d "centre of expansion". We can only point north-south, east-west or up-down. So, there is no "centre" to our universe. All galaxies move away from each other, just like all the dots move away from each other as the balloon blows up.

    That is incorrect. There is lots of good evidence supporting the big bang theory. In particular, the existence of the cosmic microwave background radiation itself.
     
  7. ranthi Registered Member

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    That baloon thing is an interesting theory. But, since I am illequipped to imagine an expanding universe without a center..let me introduce a couple of counterpoints.

    To say that we cannot point to the center of the universe doesnt mean that there isnt a center...in my mind. To me, it says that there is a center..it just originated outside our universes frame of reference. Its an interesting, as of yet unprovable, speculation...and will be interesting if it pans out..but I dont buy it at this time.

    The energy for expansion also had to originate from somewhere, unless the universe is just running on kinetic energy at the moment. I think I read somewhere that some scientists believe the universe's expansion is actually speeding up...where is this energy coming from for accelerated expansion?

    The CMB radiation is said to be what mostly...2.7 k or something? Is it colder (wrong word I know) elsewhere or is that the least amount that the CMB can be?

    Almost forgot. What I meant by evidence of a big bang is that we arent seeing in our telescopes any sort of evidence of a massive explosion (via light) coming from anywhere...
     
  8. James R Just this guy, you know? Administrator

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    The actual theory behind it is Einstein's theory of General Relativity. Don't think that the balloon analogy is just an idea that randomly popped into somebody's head. That is just a lay-person's explanation. Behind it is a lot of complicated mathematics and physics.

    A couple of points here. First, realise that a normal expansion doesn't require energy. Consider an exploding firework, for example. After the initial bang when the thing goes off, all the fragments move outwards in the sky from the point of the explosion, but there's no extra energy driving their outward expansion - only the initial energy in the original bang.

    As for accelerating expansion, that does require an energy source. In the case of the universe, physicists are postulating something called "dark energy". I think you could imagine that each point in space is sort of like a coiled spring that is slowly uncoiling, pushing space apart.

    There are slight variations in the radiation temperature of the CMBR, which correspond to the "clumping" of matter in the early universe. The overall temperature, however, is due to the expansion of the universe. Originally, the entire universe was at a temperature of billions of degrees. As it expanded, it cooled, so today the radiation temperature is 2.7 K.

    But that's exactly what the CMBR is.
     
  9. superluminal . Registered Senior Member

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    Correct me if I'm wrong here James, but isn't the "rising raisin bread" analogy better?

    Picture the universe as an infinite loaf of raisin bread dough. As it expands, all of the raisins think they're at the "center" of this universe as every other raisin seems to be moving away from them.

    But they realize that that would imply that they were in a privileged position at the "center" of the universe. A better approach is that they are just one of many (infinite?) raisins in an expanding "dough" (space). The CMBR is the isotropic heat signature of the initial "cooking" process.

    Is this not how cosmologists currently view the cosmos? Most likely infinite in extent with the expansion encompassing all of infinite spacetime?
     
  10. ranthi Registered Member

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    If I was to accept the idea of the infinite universe, I would also have to accept the idea that the universe has no definitive age. I do not believe anything is infinite or ageless.

    Wasnt it originally postulated that the entirety of the universe was contained in a singularity that, for lack of better words, reached a critical mass..hence the big bang?

    Didnt scientists need a frame of reference to theorize that the CMBR was a billion degrees or more at the universes birth? I imagine they would have gotten their evidence at the edge of the viewable universe...and if the universe is infinite, it might have infact been much hotter.

    As far as dark energy and dark matter..I am really not up on these as to what they are or are supposed to be, so I cant comment on them.
     
  11. Gustav Banned Banned

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    hmmm
    depends on perspective

    /confused
     
  12. ranthi Registered Member

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    Dont get me wrong, I think I get what they are saying...I just have a hard time accepting the idea. They are saying that the universe didnt originate at any specific point, they are saying the total of the infinite universe came into existence all at once and that it is continuing to expand...although I find it hard to add anything to infinity.
     
  13. Gustav Banned Banned

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    /confused x 2
     
  14. psycha Registered Member

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    I think the problem with the balloon theory is that if you use it to explain that there is no center then you also must conclude that if you travel in the same direction then you will eventually come back to your current location. Basically you would see the same star in different locations in your view of the universe. Otherwise, what's the point of cherrypicking only certain attributes of analogies to conclude basic things.

    How is the Universe Singularity different than a Black Hole Singularity, other than size. Perhaps the Universe was just a super black hole that eventually blew up.
     
  15. D H Some other guy Valued Senior Member

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    Another minor correction: While the CMBR is viewed as among the best evidence for the big bang, the CMBR did not come directly from the big bang. After the first few days, the Universe settled down to form a plasma cloud. Photons in this cloud were constantly being absorbed and reemitted. Think of a big bank of fog. End result: The initial universe was opaque.

    The ongoing expansion of the universe made the universe cool down. After about 380,000 years of expansion, the universe cooled to below the plasma point. Electrons and protons combined to form hydrogen atoms and the light finally escaped. It is this rush of light with a blackbody temperature of about 3000K that we see today as the CMBR with a blackbody temperature of about 2.7K.
     
  16. kmguru Moderator

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    Where do dark matter fall in? Can our understanding of the nature of the universe be complete without that understanding? Has anybody theorized how they might have formed? and where they fit in like super symmetry, strings etc.
     
  17. kaneda Actual Cynic Registered Senior Member

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    James R. The balloon analogy requires a four physical dimension sphere with the universe as a 3D skin on it. How does something expand in 4D? What is inside causing this expansion? If we "punctured this balloon", would it be the end of the universe as it starts collapsing again?

    Billions of trillions of stars shining and giving off solar winds for billions of years. Does it all vanish or does all this "stuff" pervade all space? Infra-red radiation overlaps microwave radiation. Over a long enough distances, IR loses sufficient energy so that it redshifts to microwaves. A uniform CMB. Easy.
     
  18. kaneda Actual Cynic Registered Senior Member

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    D H. Even with plasma, before matter formed, it was sufficiently dense enough that the universe would have ceased to expand and collapsed back into a black hole. Yet another reason why the BB is wrong.
     
  19. kaneda Actual Cynic Registered Senior Member

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    physcha. Now you get it. Black holes do not inflate or expand, even if they are given fancy names like singularity.
     
    Last edited: Dec 1, 2007
  20. superluminal . Registered Senior Member

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    No. Only if you are missing the fact that it is space itself that is expanding, and carying matter along with it.
     

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