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Evidence of the age of the universe

  1. Jan 25, 2008 #1
    1. I'm just wondering exactly why people theorize that the universe is 13.7 billion years old.
    What is the accuracy of this estimate?

    2. How certain are cosmologists that there was a beginning to time and what evidence is there of this?
     
    Last edited: Jan 25, 2008
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  3. Jan 25, 2008 #2

    russ_watters

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    The answer to both questions is the same: the Hubble expansion. If you measure the expansion of the universe, you can just extrapolate back in time to when the universe had zero size. Acceleration of the expansion has thrown a little bit of a monkey-wrench into the idea, but I think it is considered well covered today.
     
  4. Jan 25, 2008 #3
    The current "best estimate" value of 13.7 billion years comes from the detailed observations of the cosmic microwave background (CMB) made by the WMAP sattelite. This age is inferred from the current angular size of the anisotropies in the CMB, and is therefore dependent on the details of the cosmological model used.
     
  5. Jan 29, 2008 #4
    Russ: Van Flandern says the universe has too much large scale structure (interspersed "walls" and voids) to form in a time as short as 10-20 billion years. How do you respond to this?
    cadnr: The microwave "background" makes more sense as the limiting temperature of space heated by starlight than as the remnant of a fireball. It seems to me that thay had to retro-fit the whole microwave background idea with a hammer to try and make it fit into a theory that dosnt work well in the first place.
     
  6. Jan 30, 2008 #5

    Chronos

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    Van Flandern is notorious for his speculative, unconventional ideas. Read this article for a perspective: http://www.pitch.com/2004-11-25/news/space-case/2
     
  7. Jan 30, 2008 #6
    Isn't "Hubble Expansion" based on redshift of light? I've often scratched my head over this. How do you know for sure that it is the lightsource accelerating further and further into the distance that is causing this redshift? What about all the interstellar/intergalactic dust in the way? Wouldn't that cause a "reddening" of light, the same way the Sun reddens like a lollypop in a smoke-haze? And what about this so-called "vacuum/zero-point/quantum fluctuation/dark energy"? Couldn't that refract the light also? (Is "refract" the right word? woops!).

    And what about the speed of light itself? How sure are we that it is constant? You tell us that "c" = speed of light in a vacuum = but isn't there no such thing as a "vacuum"? I mean, isn't the "vacuum" buzzing alive with more and more energies on smaller and smaller scales? Do scientists address this at all? Who knows, maybe lightspeed is infinite in a "true" vacuum!?

    I don't know... I'm not arguing for or against anything... Just full of questions lol!
     
  8. Jan 30, 2008 #7
    Makes more sense to who? Can red-shifted starlight explain the spectrum of CMB temperature fluctuations predicted by big bang cosmology and observed in the CMB?
     
  9. Jan 30, 2008 #8
    Chronos: Yea, He is a bit of a wackadoo, but even a blind squirrel finds a nut once in a wile. :)
     
  10. Jan 31, 2008 #9

    Chronos

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    Starlight reddened by intervening dust clouds would not be 'redshifted'. Redshift is a stretching of the waves of light emitted by elements in the object observed. There are only two known ways to achieve this property - doppler or gravitational effects. The gravitational explanation [the universe is a black hole] is very fringe.
     
  11. Jan 31, 2008 #10
    Sounds silly, doesn't it. The idea that there was once an 'after' that had no 'before'.

    It is a common error of logic derived from the tacit assumption that the phenomenon of existence is the result of cause and effect. Action and reaction is the explanation for most every circumstance encountered in our everyday lives, so it is easy to go with the kneejerk presumption that existence, itself, was caused.

    But if existence - the universe - was created, it had to have a creator - which must have been preceded by a progenitor which must have been, in turn, preceded by an infinite procession of predecessors. The cause and effect approach to existence yields no logical 'beginning'.

    Existence is not a condition - a state of being - it is the phenomenon of being, itself.
    Before something can act or be acted upon, before it can change or be changed it must first exist. This means cause and effect is a function of existence, not the reverse.

    The phenomenon of existence is explained by a principle, not a process.
     
  12. Jan 31, 2008 #11
    Can you say with certainty that there is not some property of space, itself, which - over vast distances - would not account for red shift.

    Before the microscope, it was difficult to get people to believe in germs. Before we presume we 'know it all' stop and think - over a very few centuries of recorded human history MOST of the conventional wisdom has been disproven.
     
  13. Jan 31, 2008 #12

    russ_watters

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    Not sure if you realize this, but at about the same time it was discovered, it was also predicted to exist independent of the discovery. It is a natural consequence of expansion: the theory was not altered to make it fit.
     
  14. Jan 31, 2008 #13

    russ_watters

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    There is no known mechanism that could account for it. But sure - as long as we don't know everything, there is always something that could be possible. Is that enough for you to be convinced the prevailing theory is wrong?
    So what does that mean? Does the fact that we don't know everything imply to you that we know nothing? That's illogical.

    The theory fits the evidence and there is no other theory that does. It is irrational to believe that the theory is wrong based on this.
     
  15. Jan 31, 2008 #14

    chroot

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    Have you ever asked an actual cosmologist if he or she "knows it all?" What do you think the answer would be? What makes you believe that any scientists anywhere think they know it all?

    The reason we keep building spacecraft like WMAP is precisely because we know we don't know it all.

    - Warren
     
  16. Jan 31, 2008 #15

    DaveC426913

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    You have just given your blessing to The Scientific Method.

    The whole point is that TSM doesn't simply allow old theories to be proven wrong, it is critical to its success in leading to new understanding of our world.

    And that is where faith-based world-views shoot themselves in the foot.
     
  17. Jan 31, 2008 #16
    Nice argument Dave. But then if there was something wrong with the scientific method, of course we would have to move beyond that as well, so as not to shoot ourselves in the foot.
     
  18. Jan 31, 2008 #17

    DaveC426913

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    Heh, well that could only come about by us asking if TSM was still the best model, then we'd have to form an alternate hypothesis and test it... then we'd gather evidence ...

    How else would be be able to form new thoughts and learn things?
     
  19. Jan 31, 2008 #18
    i really don't know either. honestly though, i think alot of our thoughts are formed through communication, which is not necessarily dependent on current scientific thought. The only way I can see scientific thought changing is as a natural evolution of communication, but of course I can see no reason for this because I am really not that smart.
     
  20. Feb 1, 2008 #19

    DaveC426913

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    ?

    Are we talking 'thoughts' or are we talking 'investigation of phenomena'?

    cuz thoughts are not constrained by the search for truth.
     
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