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Where does gravity come from

  1. May 8, 2009 #1
    During a physics test today (introductory phys) we had to find the force exerted on an object from gravity. So my mind somehow wandered off as I started wondering where gravity actually comes from. I know that's a very broad question since I guess we don't even really know where we "come from", so maybe it should be rephrased as what causes gravity... Either way, the answer seems beyond me. I'm having trouble grasping what exactly causes this force I suppose. Can anybody help me out? This is the first physics class I've taken, so if you think the answer would be beyond my understanding then I don't mind if you just say so.


    Oh and this isn't a hw question or anything. I'm just curious.
  2. jcsd
  3. May 8, 2009 #2
    That's okay, Holly - we probably would have guessed that this was not a homework problem. In fact, you could take it on as an independent study project - and when you solve it you'll get the Nobel Prize!!

    I'm just kidding, but in fact the question you've asked is sort of like the Holy Grail for theoretical physicists. There are some very successful theories that describe gravity very well, but none that actually explain why it must exist in the first place - not yet, at least!
  4. May 8, 2009 #3
    When Isaac Newton was asked this same question he famously replied "Hypotheses non fingo," which is sometimes whimsically translated as "Uhmm....." :smile:
  5. May 8, 2009 #4


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    Einstein's theory (general relativity) says that gravity comes from the curvature of spacetime - and in turn, the curvature of spacetime is caused by matter. But if you're not satisfied by that answer, don't worry, you're not alone ;-) The curvature thing was devised as a way to explain how gravity works, but like belliott4488 said, a lot of people still wonder about why it exists.
  6. May 8, 2009 #5
    Yeah, I've asked all my unversity lecturers on what they think about it, and they have no idea besides the current theories revolving around gravitrons
  7. May 9, 2009 #6
    Haha, aw rats! I guess I'll just have to add this to my list of "things that drive me nuts because i don't understand them and most likely will never understand". Or I'll just go figure it out myself since I know so much about physics. (ha ha.......) :tongue:
  8. May 9, 2009 #7
    Hey, a lot of very successful Physicists got started exactly that way! In my case, it was magnets - they seemed like magic, so I decided that I would try to understand them as well as I possibly could.

    Um, I guess that means some less-than-successful Physicists got our start that way, too. :tongue2:
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