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    Dark matter is supposedly not affected by the electromagnetic force. I kinda like the idea that neutrinos may play a major role in dark matter. Still there would be much unaccounted for matter. I'm glad we live in this day and age. These are questions that we could have answers for in the next several years.
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    Quote Originally Posted by OleCuss View Post
    I should probably be more clear. I hate the idea of Dark Matter and of Dark Energy. I want someone to solve them because invoking the concept of the unseen and the unknowable is not something that I find scientifically acceptable.
    I'm no astrophysicist, but even to my untrained self it is clear that dark matter/energy are nothing more than theoretical constructs; numbers matched to unexplained observations, used to make equations balance. Problem is, dark energy and dark matter have NOT been observed. Only effects which are (today) attributed to dark energy/matter have been observed. That's why they're called "dark;" as soon as they are actually observed, if they ever are, they will be named after whoever finds 'em...

    IINM, Einstein's Cosmological Constant was postulated to fix the same kind of problems with the universe's equations.

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    Quote Originally Posted by Cladinator View Post
    It couldn't be that. Space is accelerating faster than light, so it couldn't be photons pushing out the edge of the universe.
    But the photons are pushing out in all directions so the maximum speed that opposite sides of the universe can travel away from each other is twice the speed of light.
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  4. #14
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    Default The announcement is "hyped", by a lot

    The Australian student's discovery did not make the dark matter problem go away. It simply detected visible matter for the first time that had to be there. It isn't enough to make dark matter go away.

    Unfortunately for those who hate dark matter:

    1) The rotation of the Milky Way Galaxy (and other nearby galaxies whose rotation curves are measurable) is inconsistent by a very large factor with the visible matter distribution. The rotation curves are not consistent with a concentration of matter toward galactic ceners. The velocities are more like what a uniform mass distribution would give. Mass distributions and internal velocity distributions are related by the virial theorem for all stable objects.

    2) The internal velocities of nearby clusters of galaxies similarly have not enough visible matter to hold the clusters together. The virial theorem again requires that there must be more matter than what is visible.

    The detection of filaments connecting galaxies and clusters is irrelevant to "solving" the dark matter problem. The virial theorem related the velocities at a given radius from the center of the object to the mass contained within that radius. Mass outside that radius doesn't contribute to helping the dark matter disapear. Friz Zwicky used the Virial Theorem to detect dark matter in the Coma Cluster in 1933-1934.

    The choice is simple. If you believe in gravity, then you must believe in the Virial Theorem and individual galaxies and clusters of galaxies don't have enough visible gravitational glue to hold them together. So there must be invisible gravitational glue: dark matter.

    A similar situation arose in 1930. Pauli posited matter that could not be detected the neutrino to preserve conservation of energy, momentum and angular momentum in nuclear beta decays. It was decades before a detection could be made. But physicists are rightly rewarded by believing in conservation laws above all. Eventually they point the way to detecting new unseen entities.

    If there is no dark matter one would similarly have to discard conservation laws. (The Virial Theorem is conservation of energy and momentum bundled together.)

 

 
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