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? asked in Science & MathematicsPhysics · 1 decade ago

Unsolved physics problem?

Why do galaxies rotate at speeds inconsistent with their apparent mass?

This is one of the unsolved physics theory which existing theories seem incapable of explaining some observed phenomenon or experimental result.

Follow up:

http://www.thenakedscientists.com/forum/index.php?...

http://www.sfetcu.com/book/Unsolved-problems-physi...

Update:

Could we discuss a little about it.

Thanks.

6 Answers

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  • 1 decade ago
    Favorite Answer

    That is the origin of the infamous "dark matter" hypothesis.

    There are two main attempts to explain why galaxies spin faster than expected based on their apparent mass.

    1) There is more matter in them than is "apparent". That is, there is matter which isn't apparent, i.e. it's "dark".

    2) Gravity doesn't really follow the rule GMm/R^2. Perhaps, at distances much greater than the size of our solar system, it follows a different rule. Or it follows the same rule everywhere, but it's not GMm/R^2, but it's something that can be approximated as GMm/R^2 at scales up to the size of our solar system.

    All things being equal, I favor #2, because I don't think you should make up something you haven't observed just to avoid fixing a broken theory. Dark matter could be like the "luminiferous ether" imagined before Einstein's special relativity.

    However other observations seem to back up the dark matter theory, for example observations of the way galaxies collide seem to show the dark matter portions having a distinct effect.

    It's supposed that maybe dark matter is some kind of matter that doesn't interact with any of the forces of the universe other than gravity. It's not too hard to imagine, really. We know of forms of matter that don't interact with the electromagnetic forces, such as neutrons. Why shouldn't their be forms of matter insensitive to the other forces as well?

  • 1 decade ago

    the galaxies rotate at speeds inconsistent with their apparent mass is because we do see all of it. I am referring to it as being the theoretical Dark Matter. There are very strong proofs that indicates that dark matter exist. One the is the inconsistent speed of and apparent mass. dark matter makes up about 75% to 80% of the matter in the Universe...

  • 1 decade ago

    The "How" of why things are, will be the only "constant" that we humans experience. There are things that we cannot experience, and therefor must theorize. They're called theories.

    This is your specialty, where I have no specialty, and therefore, am a master of nothing. I accept what I cannot understand, or change, because anything else is insanity!

    I can help you keep your computer working though..

  • Anonymous
    1 decade ago

    i guess it will take another 100 years to get the answer to this

  • 1 decade ago

    hehe.....u r a nyc physicist 2 thnk abou' ths.....:))

  • 1 decade ago

    great!

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