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Is there an end to the universe?

  1. Mar 23, 2005 #1
    Do you think that there is an end to the universe? If so, why? If not, why not? Currently, it seems to be more likely that there is an end. Wouldn't there need to be an infinate amount of energy created in the bigbang to make an endless universe? If there was infinite energy, we would surely know of it (perhaps not exist because of it.) Also, why is the outward expansion of the universe slowing down. The question is, how can anything slow in an place with no friction or very low gravity(remember, as long as there is mass there is gravity). Could this mean a large mass at the center of the universe? Because objects 'sink' into space, this is entirely possible.

    Just sharing a little bit of deep thinking, which I do alot.
     
  2. jcsd
  3. Mar 23, 2005 #2
    Hmm... last I heard the universe was accelerating outward, not slowing to a halt. This phenomenon has caused much speculation and has led many to consider the possible existence of "dark energy." It is my belief that gravity plays no part in slowing the expansion of the universe down, and in fact depends on the expansion of the universe in order to work.

    As for an "end" to the universe, I believe that there must be one, as it is hard to imagine time to have infinite spacial extent (yes, spacial extent).
     
  4. Mar 23, 2005 #3
    It is still expanding, just it appears to not be expanding as fast. In about 8 billlion years it will stop altogether(if it keeps it current rate of slowing down) and about 12 billion years after that it will be condensed into a very dense spot of matter,(my timeline is probably off, so fell free to look it up, because i really don't feel like doing it(because i'm really lazy))
     
  5. Mar 24, 2005 #4
    I guess there is an end for the universe. i forgot where i read this. It is some thing like this. It is finite yet unbounded. Like this earth. You can travel due east as long as you want and still not found the "end". yet the surface area of this earth still remain the same. if i remember correctly, the universe far less the same. There is exact volume of the universe yet there is no "end" for it. If they say that the universe is expanding, what i'm thinking is that the volume increase. just like the earth, it's radius increase (supposively). the best analogy is like video game of 10-20 years ago. where if you walk left, you will appear at the right.

    Then my question is, is BIGBANG strong enough to increase the dimension of this universe.
     
  6. Mar 24, 2005 #5
    Theres a finite amount of energy in the universe.

    If the universe keeps expanding, the energy density will approach zero, the temperature will approach 0 Kelvin and time will slow to a halt.

    If the universe shrinks, the energy density will approach infinity, the temperature will approach infinity. All energy will condense into mass whose density will appraoch infinity and the universe will become a singularity.
     
  7. Mar 24, 2005 #6
    Apparently, the size of the universe is determined by the size of our telescopes. WE ARE GODS. :surprised
     
  8. Mar 24, 2005 #7
    For three dimensional observers there is no end to the universe. For four dimensional observers there is indeed a finite universe. This is how we (being three dimensional observers) can construct a formula to determin the volume of the universe using one extra coordinate. this system is called Gaussian coordinates in differential geometry.

    regards
    marlon
     
  9. Mar 24, 2005 #8
    I'm looking at a 3 dimensional picture, on a 2 dimensional piece of paper, noticing that it doesn't move. The forth dimension is time. We are forth dimensional observers.
     
  10. Mar 24, 2005 #9
    I think they have discovered that the universe (the farthest things out in it, at least) is accelerating away, not slowing down. This doesn't mean that the universe wont end though. Check out "end of the universe(theory)" under theory development. If the universe is a light switch, would you say it is on or off?
     
  11. Mar 24, 2005 #10
    Light from far away objects is already on the way to us that will include enough information that will confirm the inevitable reverse of “expansion” to a gravitational collapse of everything we know and see. But that light data still many Billions of light years away, don’t expect it to reach us in our life times.
     
  12. Mar 24, 2005 #11

    chroot

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    Fibonacci,

    Others are right and you are wrong. The current consensus among cosmologists (supported heavily by empirical evidence from e.g. WMAP, 2dFGRS) is that the universe's expansion is accelerating, not slowing down.

    The universe must fall into one of three categories, depending upon its matter density: open, closed, or flat. Of these possibilities, the closed universe collapses into a Big Crunch, and thus has a finite lifespan. The other two both suffer "heat death," which is large-scale thermodynamic equilibrium. Everything eventually will become the same temperature, so there will no longer be any reservoirs of heat from which we can extract energy to do work. Stars, biology, and indeed every other system which depends on thermodynamic inequilibrium will come to a stop. The universe itself might have an infinite lifespan, but after heat death it'll be pretty much useless.

    - Warren
     
  13. Mar 24, 2005 #12

    DrChinese

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    There is much evidence that the expansion is accelerating. The current estimate of the diameter of our 13.7 billion year old universe is 156 billion light years. In the distant future, the expansion will be such that only light from Andromeda will be able to reach our galaxy as everything else will be receding from us in excess of c. Already there is a significant portion of the universe receding faster than c, including a few objects that are receding at more than 3c relative to us.

    Strange, but true!
     
  14. Mar 24, 2005 #13
    No, you are wrong in this case. You are mixing this with the space time continuum. gaussian coordinates are NOT the same and this fourth coordinate is not time.

    marlon
     
  15. Mar 24, 2005 #14
    Thanks for the clarification. Now, what are we?
     
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