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Is the Milky Way galactic blackhole slowly sucking us in?

  1. Dec 14, 2011 #1
    with the newest discovery of biggest black holes in the universe, i suddenly had this weird thought: what if they're a draining hole of the galaxy, the spiraled arms and the shape, all looks awfully similar to a whirlpool, with black holes at the center of nearly all galaxies
  2. jcsd
  3. Dec 14, 2011 #2


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    Don't be afraid, this is NOT how black holes work. They are not literal "holes" in space that devour everything nearby. A black hole of 2 times the mass of the sun behaves EXACTLY like a normal star of that mass as long as objects stay outside a distance equal to the radius of the normal star.

    For example, if the radius of the star was 1 million km, then as long as you stayed at a distance of at least 1 million km from an equal mass black hole, the gravitational pull is exactly the same. It is only once you get closer to the black hole that the gravity increases, since it is compacted into a much smaller volume of space.

    If you compressed the Earth to 1/2 it's size, it would have no impact on how the Moon orbited, but the surface gravity would be somewhere on the order of 4 times as much as it is now. Make sense?
  4. Dec 14, 2011 #3
    Black holes aren't cosmic vacuums. If a black hole the mass of the Sun (which wouldn't normally occur in nature, but can in principal) were to replace the Sun, we would continue to orbit around it at the same rate. This back hole is really heavy, but REALLY far away.

    Don't lose sleep over it.
  5. Dec 14, 2011 #4
    Awesome example of gravity. Imo as easy to absorb as the "rubber sheet" analogy, but much much more descriptive of the physics.
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