Gravity a pushing force?

  1. I've always thought about gravity as a pulling force but perhaps it isn't. Is there anything fundamentally wrong with thinking about gravity as a pushing force attenuated by matter?
     
  2. jcsd
  3. ZapperZ

    ZapperZ 30,451
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    Physics isn't just "what comes up must come down". Physics must also say when and where it comes down.

    When you are considering something like this, you simply cannot do it via hand waving argument. You need to produce accurate, mathematical description that matches all our current observations on gravity. It is only after you can present that will something like this be considered and taken seriously. Otherwise, you will be another one of the people who come here with some vague idea and wanting the rest of us to do the dirty work of falsifying something that is half baked. This is not something we do in this forum, because there are in infinite number of such scenarios that anyone can come up with.

    Zz.
     
  4. Bandersnatch

    Bandersnatch 1,517
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  5. Are you referring to what Michio Kaku said in the TV documentary on Einstein?

    Chet
     
  6. Matterwave

    Matterwave 3,860
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    When Michio Kaku made that statement... my mind exploded...:eek:
     
  7. What was his comment?
     
  8. Believe it or not, he said that gravity doesn't pull you. The relativistic explanation of gravity is that it pushes you. Here is a link to the documentary, now available from youtube:



    This is one of the shows that got me interested in studying Relativity. I wanted to find out whether what they were saying was correct or not. In this case, Yiiiiiiiiiii!!!!!!

    I don't know how he could say something like this in a medium where it would be preserved forever for people to see.

    Chet
     
    Last edited by a moderator: Sep 25, 2014
  9. A.T.

    A.T. 6,281
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    He talks about "space pushing" objects towards the mass after 2:00:

    https://www.youtube.com/watch?v=fEZupmpTcOU

    I guess it is his way to describe inertia: As an interaction with space, which opposes deviations from free fall. Not my favorite way to put it.
     
  10. Yes. He also mis-states in no uncertain terms that Special Relativity does not apply to accelerating objects. Many of the things said in this video are a PF "worst nightmare."

    On the other hand, I love this video because of the historical perspective and the personal stories, including Einstein's "soap opera" personal life, his relationship to Planck and Haber, and the stories about the attempts to prove GR using solar eclipses.

    Chet
     
    Last edited: May 5, 2014
  11. Man, that was a terrible video. Why do they even try...
     
  12. Jano L.

    Jano L. 1,273
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    The story about push seemed strange to me too at first. There is this curved 2D surface which pushes the marble to make it move in circles. Perhaps they just wanted to communicate the idea that gravity in Einstein's theory is similar to the curved surface. Instead of "curvature determines the trajectory" they said gravity pushes the body to make it similar to the curved surface where the marble indeed moves in circles due to push (contact forces of constraint cannot pull)...

    ...I rather would not be too harsh on them. This is probably close to where one can go without using mathematics...
     
  13. A.T.

    A.T. 6,281
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    That is an even worse analogy. Discussed many time here.
    https://www.physicsforums.com/showthread.php?p=4597121#post4597121

    One can do much better without using mathematics:

    https://www.youtube.com/watch?v=DdC0QN6f3G4

    http://www.physics.ucla.edu/demoweb..._and_general_relativity/curved_spacetime.html
    http://www.relativitet.se/spacetime1.html
    http://www.adamtoons.de/physics/gravitation.swf
     
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