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Contracting Universe?

  1. Mar 29, 2012 #1
    I have read a few books aimed at beginners with an interest in the universe. It seems to be conclusive that the Universe is expanding but I do not understand why. I am in no way saying the Universe is contracting but I am asking why I am wrong or what facts am I missing. The evidence I have heard for the expansion of the universe is measuring the lightwaves between us and other stars and from that scientists determine if the sun is moving away or towards our planet.
    However, even with the proof of a star moving away from us, could it not be possible that the star is moving towards something. For example, I have seen an experiment using an elastic string with 5 equally spaced rings. When the string is the pulled the outside ring on the left and right move the furthest away. This was used to show how stars are speeding up showing expansion but could they not be speeding up as a result of an object being so massive and so far away that it is warping space to bring objects closer and the closer they get the faster the pull on the object becomes?
    I am sure I did not just prove some of the greatest minds on Earth wrong with my observations so please explain in as much detail as you could the details I am missing. Also, a few articles I read cited the Big Bang caused the expansion and I understand that but could it not be possible the expansion has ceased and is now contracting back to a point or points?
     
  2. jcsd
  3. Mar 29, 2012 #2

    phinds

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    The expansion of the universe is an experimental fact. WHY is it expanding? Well it started off expanding because all that energy didn't like being so compact, so expanded and created matter. In the tiniest fraction of a second it expanded some staggeringly large amount (I seem to recall numbers like 10E50 or maybe it was 10E80). THEN it stopped expanding so fast (that was called inflation) and expanded at a more sedate rate, and everyone up until about 10 years ago was sure it was slowing down and would eventually reverse and collapse.

    Then measurements were made and to everyone's surprise it not only wasn't slowing down it was speeding up. WHY is it speeding up? ... well it's this totally not understood stuff called "dark energy".

    You've probably already read all this and just don't want to believe it (or find it very hard to believe) but it's the way it is.
     
  4. Mar 29, 2012 #3
    Hi JPadinske,

    The expanding universe is an experimental fact and rests on three major pillars:

    I. Galactic Redshift

    Because of what is known as the Doppler Effect, light sources moving away from you will appear reddened and dimmer. This is because the wavelength of the light is stretched as it is being emitted. You easily notice this with sound, a train passing by changes pitches. In 1929, Edwin Hubble noticed redshift in galaxies, showing that they are moving away. Though, note that galactic redshift is caused by the expansion of space, not the actual galaxies just moving away from us.

    II. Cosmic Microwave Background

    Because light has a finite speed, the farther you look away form your position, the older the light you see. So, if you look sufficiently far away, you will see the cosmic microwave background, an image of the universe 300,000 years after the bang. Analysis of the CMB shows that the universe was very hot, and very dense in it's early state, showing it has expanded.

    III. Supernovae

    Supernovae, or the explosion at the end a stars life, are an excellent "candle" to observe cosmic expansion. We can calculate the distance of a supernova, and compare it to the distance of a more recent one. This shows conclusively that the universe is expanding.

    On top of this there is still more evidence. For an article on the expanding universe, see here:

    http://www.mso.anu.edu.au/~charley/papers/LineweaverDavisSciAm.pdf
     
  5. Mar 29, 2012 #4

    Drakkith

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    The problem is that this would require some massive object be completely surrounding the observable universe, like being inside immense hollow sphere. EXCEPT that inside a hollow sphere the force of gravity is equal at all points inside with no net force in any direction. So, no, this could not be the result of a massive object outside our observational range.

    It is not possible according to our current understanding. When we look around we see things getting further away from us in every direction. The time frame for these objects is from about 50 million years to 13 billion years depending on the distance, so unless the entire expansion had somehow stopped and reversed in the last 50 million years or so (the time it takes light to travel from the closest objects that are moving away from us) then no, it isn't possible. And we have no reason to suspect that it has reversed, as it appears to be accelerating.
     
    Last edited: Mar 29, 2012
  6. Apr 1, 2012 #5
    I had heard of dark matter just was not sure of its relation to the Big Bang. Any books or videos you have seen that you would recommend for this topic?
     
  7. Apr 1, 2012 #6

    Drakkith

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    http://en.wikipedia.org/wiki/Dark_matter
     
  8. Apr 2, 2012 #7
    You also want to read on dark energy.

    http://en.wikipedia.org/wiki/Dark_energy
     
  9. Apr 2, 2012 #8

    Chronos

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    Wiki is not a terribly reliable source. Check out arxiv.
     
  10. Apr 2, 2012 #9

    Drakkith

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    Perhaps, but I don't find arxiv to be..."readable" by most people just getting into a subject.
     
  11. Apr 2, 2012 #10
    Checked out arXiv, read one article and mind is officially blown, had to inch my way through it and look up a lot of words and such but wow amazing. Thanks a lot everyone
     
  12. May 30, 2012 #11
    First off please excuse the noob but here goes.

    I found an extract from a book that goes a long way to question the validity of the Expanding Universe theory. It is from "Dark Matter, Missing Planets and New Comets: Paradoxes Resolved, Origins Illuminated" - by Tom Van Flandern. The extract I refer to is at the end of the book. The chapter starts on page 398 and only goes to page 400. It basically discusses other causes of Redshift with an emphasis on the question "Is the universe expanding" Yes it was written in 1993 but I still think there is some value in it. Even Hawking has admitted that the BBT isn't the end of the puzzle and that we need to adopt aspects of other theories to determine the "ultimate formula".

    Unfortunately I am unable to post links as yet. I came across the book when researching other possible effects that could cause Redshift. As you can probably tell I am a big fan of the Infinite Universe Theory. At the same time I can see some aspects of the BBT can apply.

    Thanks and I hope my first post here wasn't a pointless one!!
     
  13. May 30, 2012 #12

    phinds

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    Welcome to the forum.

    Yes, the BBT is incomplete in that it doesn't do ANYTHING to explain how it all started (the singularity where the theory breaks down), but the analysis of the expanding universe SINCE the singularity is pretty well understood. That the universe is expanding is not really open to debate any longer. All alternate theories ("tired light" and so forth) have been shown to not fit the facts. Something written in 1993 is VERY unlikely to change that.

    It's good that you are open to questioning existing theories, but it would be a good idea to find out about them and see why they are accepted before you take on something that you think disproves them.
     
  14. May 30, 2012 #13
    Thanks mate, for the input and advice.

    I don't know if the expanding universe theory is as solid as we think. From what I understand the only "observation" that is being touted as the reason why the universe is expanding is Redshift. Yet I am interested in considering the possibility that Redshift can be caused by other phenomena. For example I am entertaining the multiverse theory. In this case could Redshift be a result of deterioration of light i.e. the energy we need, to see, and in fact what we are observing is a "meshing" of the multiverse?

    Pretty far out I know but I can't see any harm in proposing and discussing existing theories and perhaps developing your own. It is important to note that I'm not going into this with any prejudice or agenda. I am willing to listen and learn.
     
  15. May 30, 2012 #14

    phinds

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    No, as I said above, "tired light" as been shown to not fit the facts. Again, I suggest that you read more about WHY the "expanding universe" is taken as well established before you try to disprove it. I suspect you'll find that all of your objections have already been answered.
     
  16. May 30, 2012 #15
    Thanks again.

    At least I got something constructive out of my short stay. Unfortunately I was lambasted for asking some questions.

    As I said I wasn't about disproving or pushing an agenda just wanted to learn and understand. It's a shame that this forum doesn't allow for questions to be asked especially as it is being portrayed as the ducks guts when it comes to Physics.

    Take it easy guys but take it!
     
  17. May 30, 2012 #16

    Drakkith

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    Trust me, you have not been "lambasted" by Phinds. He has merely explained that the other possibilities for redshift are not sufficient and don't fit the observations as well as an expanding universe does.

    Please, you cannot come to a forum dedicated to teaching the current mainstream theories in science, ask questions about something that goes against those theories and then expect not to be corrected. I think you have misinterpreted Phind's answer as a door slamming in your face. The door is open if you want to learn!
     
  18. May 30, 2012 #17

    Chronos

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    The 'best' [most simply explained] articles on arxiv normally contain the word 'review' or 'pedagogical' in the title. So, in the search query type 'dark matter' in the abstract and 'review' in the title block. You get 31 hits this way, including
    Mini--Review of Dark Matter: 2012
    http://arxiv.org/abs/1204.2373

    If you substitue 'pedagogical' for 'review', you get 2 hits - including this outstanding paper by padmanabhan:
    Advanced Topics in Cosmology: A Pedagogical Introduction
    http://arxiv.org/abs/astro-ph/0602117
     
  19. Jun 1, 2012 #18
    Drakkith, as it turns out you can't delete an account so I guess you're stuck with me, for now! You're right I wasn't lambasted by phinds. If you read my posts above you would realise that the constructive part of my stay was thanks to phinds. I was lambasted by ZapperZ for starting a topic with the question "what happens to say an asteroid or meteor or any accelerated particle even if it managed to (at least a portion of it) reach the so called surface or edge of the expanding universe?" I was hoping to get an answer but within 15mins my post was removed and I received a warning. I am guessing the theory is that it would/could never reach this surface because the universe is expanding at "c".
    It's very disappointing when you get shut down by someone for no real reason, when all you want to do is learn. The field of physics in general is so broad now and still broadening that it's hard enough to get anywhere to begin with and then to be essentially labelled a "crackpot" for posing some questions doesn't do much for the status of PF and the stigma already attached to the boys club that is The BBT.
     
  20. Jun 1, 2012 #19

    Drakkith

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    I cannot do anything to this "stigma" of the BBT and I wouldn't choose to do much different involving PF. In order to keep the forum running smoothly certain steps must be taken which unfortunately do sometimes lead to innocent people with the best intentions of learning being put off by being receiving a warning or infraction by an admin. All I can suggest is to understand why these things have happened and not hold it against anyone.

    As for your removed thread, since it is believed that there is no edge or surface to the universe your question is entirely moot.
     
  21. Jun 1, 2012 #20
    I will do my best to stay within the rules........

    In regards my point being moot.

    Could you perhaps explain this a bit better or point me in the right direction. I understand the analogy used to describe the BBT i.e. expanding universe, is a inflating balloon. Is it being suggested that there is a type of "blending" that occurs at the outer most reaches? Regardless, I think my question still stands, as there must be some kind of interface to pass through or a type of transition that occurs out there?

    Thanks again for your time and comments.
     
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