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Help the newb

  1. Mar 18, 2010 #1
    Hi all I am a bit of a newb.
    could someone answer my simpleton questions for me.

    when in space under zero gravity, is it possible that with we are all falling together so what we call zero gravity could be a big free fall, I know we are not falling in relation to the cosmic microwave background but could that also be falling with us through another dimension can that be ruled out.

    what percentage of the gravity that causes a blackhole acts on our universe.past the event horizon?

    with all the matter that gets sucked into a blackhole at the speed of light does this cause a magnetic field and does and how big is this. i imagine it to be powerful could this act as a replusion force to slow down the pull of the black hole?

    Does the massive amount of energy caused by all the super novas that go off in the galaxy have a part to play in the expansion of the galaxy?

    Do planets magnetospheres stop them from gravatationally attracting?

    does the universe have a magnetosphere?

    sorry for all the questions I have started reading into the subject recently but the more i read the more questions i have!

    oh and What is causing that hexagonal polar region on saturn and ideas?
  2. jcsd
  3. Mar 18, 2010 #2


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    1) In fact, Einstein showed (using his space-elevator thought experiments) that the effects of free fall is equivalent to zero g, and that standing here on earth is equivalent to being accelerated at 9.8m/s^2 up! (Locally). This is why stuff like the vomit comet work. The airplanes allow you to feel zero g, by essentially free falling for a while (they actually take parabolic paths).

    2) "Percentage of gravity" is not a well defined term. All I can say is that the gravity due to a black hole DOES affect things outside of the event horizon.

    3) The No hair theorem says that a black hole can be entirely described by its mass, electric charge, and angular momentum. Therefore, the magnetic field isn't something that a classical black hole should have. However, there are some hypotheses that posit black holes with magnetic fields.

    4) I don't think that the energy from super-novas will affect the galaxy in this way. The gravity of the galaxy is more than sufficient to keep it tightly bound. Also, super novas tend to release a lot of their energy in neutrinos which don't interact with matter all that much. Most of the rest of the energy is released in photons which have a very low momentum (p=E/c). Only a fraction of the energy is given off by the shockwave of matter, and since the ISM is so diffuse (and stars are, in general, diffusely distributed), there's no real effects on the galaxy as a whole (but the shockwave CAN produce pretty colors by exciting the ISM around the star).

    5) Magnetism has nothing to do with gravity (at least, not in the traditional sense). Magnetospheres won't have any affect on the gravitational fields of planets.

    6) This question isn't well defined. The universe definitely has components (e.g. stars, planets) which have magneto spheres.

    7) I have no idea what causes the Hexagonal polar regions.
  4. Mar 19, 2010 #3


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    A black hole is indistinguishable from a normal denizen of the universe wrt gravity. You dont know its a black hole until you reach the event horizon.

    Supernovae have no appreciable effect at galactic scales.

    Black holes have no known intrinsic magnetosphere, but, infalling matter can do the job.

    Magnetism has no known affect on gravity.

    The universe does not have a magnetosphere, there is nothing outside the universe for it to exert an influence.

    Google on the saturn polar hex thing, it is nothing special.
  5. Mar 19, 2010 #4
    The universe does not have a magnetosphere, there is nothing outside the universe for it to exert an influence
    Thank you for the answers. I meant does a galaxy have a magnetosphere doh!Taxi!, Gravity aside would a magnetosphere attract or repluse another magnetosphere?

    Does anyone have good tips on dvds or books for beginners?
  6. Mar 19, 2010 #5


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    Yes, if they were oriented correctly. The magnetic field of the Earth is similar to a very large bar magnet. So if you had the N pole aligned with another N pole, then they would repulse as in a bar magnet. Usually, tho, the magnetic fields aren't nearly strong enough to have any attraction-repulsion effects with objects far from it (and the poles don't usually line up).

    I don't think the Galaxy has a magnetosphere since on average the magnetic fields of the components should cancel out. There's no external magnetic field which could align all those poles (like in a bar magnet)! And there's no reason to suspect that there'd be a dynamo effect going on, at least for me. The dynamo effect is, however, not well understood.
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