Why is space expanding and matter including galaxies not shrinking?

  1. I know it probably looks like a completely stupid question.. But I can't find the answer. Hopefully you all can help me out here.

    Essentially, all galaxies are moving further apart, from each other.. each spot in the universe is said to have the same effect of everything moving further apart from each other. This is known via the numerous red shifts.. But, what is the evidence that disproves it is not space/time that is expanding, but it is the galaxies and all matter are not shrinking, all relative to each other, thus creating the widening gap between galaxies and the red shift that ensues due to this furthering gap?
     
  2. jcsd
  3. DaveC426913

    DaveC426913 16,074
    Gold Member

    There's at least one flaw in this logic. Galaxies shrinking in place would not get further apart. They would just shrink.
     
  4. I say yes they would, because, upon shrinking, the end of their physical realms diminish, thus creating more space in between the two galaxies.
     
  5. DaveC426913

    DaveC426913 16,074
    Gold Member

    Inflate two large balloons till they are a foot in diameter. Place them ten feet apart. Now let the air out of them slowly. When they are half the size (6" in diameter), they will not be 20 feet apart, they will be 11 feet apart.

    In the real world, the galaxies are drifting apart much more than 1x their own diameter.

    Note that you are beginning to form your own hypothesis here. But the onus is not on me to poke holes in it, the onus is on you to demonstate, not only that it is self-consistent, not just to patch up the holes in it, but to show that it explains our observations better than our existing theories. Until then, we go with the best theory.
     
    Last edited: Apr 9, 2008
  6. Do we know the speed of spatial expansion then? If so, can you explain somewhat? If so, how do we know it wouldn't coincide with the same rate as the shrinking of the galaxies?
     
    Last edited: Apr 9, 2008
  7. DaveC426913

    DaveC426913 16,074
    Gold Member

    Read up on the Hubble Constant. Looks like about 73.5km/sec per Megaparsec.
     
  8. Hi WW III Angry,

    I can confirm that your idea is beyond brilliant, because I thought of it first. But it turns out that Sir Arthur Eddington, the famous UK scientist, thought of it back in the 1930's. The earlier PF response by Marcus addresses your question:

    Marcus response

    Jon
     
  9. Yes, but that link doesn't show an answer to this question: how do we know that galaxies are not decreasing in size that corresponds to create Hubble Constant rate of dispersement throughout the universe, which to our eyes if all things are shrinking relatively, they would always appear to be the same size, thus my dilemena.
     
  10. Sorry, your link wasn't working.
     
  11. nrqed

    nrqed 3,048
    Science Advisor
    Homework Helper

    Maybe I misunderstand your idea but if another galaxy would be shrinking, parts of it would be moving toward us and parts of it would be moving away from us, yes? (asuming that our own motion is negligible but even fi we include it the end result is the same).
    However we never observe parts of galaxies moving toward us (except for "nearby" galaxies)
     
  12. Well no, because gravity still remains relative, keeping the galaxies in place in the same (well possibily unknown manner now, of dark matter/energy as well as the matter of the galaxy) So, more often than not, galaxies would be in its entirety still moving away from us, that means our galaxy is shrinking as well, even perhaps you and me..
     
    Last edited: Apr 9, 2008
  13. Don't know why the link didn't work, but go to p. 3 of the Forum, where kmarinas asks "Which conserves energy best, expansion of universe or shrinking of matter?"
    at 02.03.08 at 02:13

    Jon
     
  14. The rate of expension of the galaxies is basically known to be roughly 1000km/s which would be roughly enough to make the universe be like 30 million light years across, which isn't quite as big as the 78 billion light year radius some estimate gives.

    A typical galaxie like our own is 100,000 light years across, so, its hard to believe the galaxie are shrinking when theres no explanation for it. Well, since we're talking astrophysics, doesn't always have to be an explanation, however, it makes a lot more sense that the galaxie are further away because of the expension of the universe, then some unknown shrinking force.

    For one, if your shrinking force was to be exactly as you say it, indistinguishable from expension, we run into the same problem as when we try to work the math with the speed of light not being a constant.

    The whole science of man is based on multiple assumptions, such as whats true here is true elsewhere, if we can't use them, then we're basically screwed anyway.
     
  15. Yes, thanks I see it.. but yes there really isn't an answer yet, because to go further would require scientific foundation for what it than just pure logic and I'm not really sure how exactly to go about doing that myself! As far as for what Marcus said, it is possible though that inside galaxies the the distance of planets itself, well, could they be getting further apart and or as matter shrinks but being very undetectable modern day, yet able to be detected better outside of our galaxy as it is may indeed have a different rate for galaxies as a whole... hmm.. I doubt it yes, but, I think to pursue any further would require data that would need to be debunked.. Yes, it should be pursued scientifically in order to be tested.
     
  16. I prefer the term "condensing" to "shrinking".
    Why can't both expansion of space and condensing of galaxies be occurring simultaneously?
    If matter and energy can not be created or destroyed how is more space being created between the galaxies? at an accelerating rate?
    Space is different from matter and energy. It is nothing.
    How does space get "warped" (known as gravity) if it is just the NOTHING between STUFF?
    Space is very intimately related to gravity, mass, acceleration,energy and of course, time.
    Sorry, that's all I've got...
     
  17. Chronos

    Chronos 9,856
    Science Advisor
    Gold Member

    I find the idea uncomfortable because it confers us a priveleged location in the universe.
     
  18. I think Marcus is correct that the old and often mentioned "shrinking matter" hypothesis does nothing to explain the inhomogeneous component of expansion. On the other hand, it seems to me that the "shrinking matter" hypothesis carries a slightly more plausible explanatory power as an alternative to the uniform acceleration of expansion attributed to dark energy or the cosmological constant. In a relativistic view, an expansionary constant is the isotropic, homogeneous flip side of a constant of shrinking.

    However, the "shrinking matter" hypothesis probably adds more complexities than it resolves, relating to a changing speed of light, fine structure constant, gravitational density, etc. So unless someone is willing to invest a lot of technical, mathematical analysis in developing a complete theory based on it, philosophizing about it seems like mostly a waste of time.

    Jon
     
    Last edited: Aug 17, 2008
  19. Expanding space: A photon's wavelength increases as space expands while it is in transit.

    Shrinking matter: When matter was larger, the photons it emitted had a larger wavelength.

    Expanding space: Distant objects tend to be time dilated as a result of their receding due to the expansion of space.

    Shrinking matter: Very distant objects in the past tended to be larger than they now but their "internal clocks" have been a lot slower too.
     
  20. If galaxies were actually shrinking or condensing, the overwhelming amount of red-shift we see would be hard to explain. Think of it this way- Two galaxies are drawn on a sheet of paper. One on the left and one on the right. Then they are condensed to a smaller size. Something becomes readily apparent. The far right side of the galaxy on the right and the far left side of the galaxy on the left are now closer together than they were before. Where is the blue shift to justify this?
     
  21. cristo

    cristo 8,394
    Staff Emeritus
    Science Advisor

    This thread is based on speculation, and is thus done. Please remember that all discussions in the technical forums must be related to published, peer-reviewed material, preferably with references.
     
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