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How does gravity work?

  1. May 25, 2006 #1
    Ok, since my thread got locked, I will just post a topic on how everyone else thinks gravity works. Sorry, I didn't notice there was a forum for just theories. Also I'm only high school educated and wouldn't know the exact way to put my theory in a mathematical formula. I would just like a discussion on the topic. I've looked lots of places and can't get any answers on how gravity works at the molecular> level. I forgot the link to this forum but I used so visit occassionaly a couple years ago and would've came here sooner. But thanks for any replies.
  2. jcsd
  3. May 25, 2006 #2
    Before I can answer this, I have to question what you mean by "how gravity works." We don't really know how anything works; matter curves spacetime, we don't really know how that works, but we can provide detailed quantitative predictions about what will happen.

    If you are questioning how the mechansim of gravity works, I can't answer that (and I doubt anyone else seriously can), if you are, on the other hand, question about what the mechanism is, then I can provide a better, but perhaps just as unsatisfying, answer.

    Apart from colourful analogies which may illustrate the point but not fully convey it (like a sketch of a masterpiece of fine art), you will not be able to get much about the most verified theory of gravity, a.k.a. General Theory of Relativity, from forum posts. Others may well be willing to offer these analogies, but I will waste neither your time, nor mine.

    If you want to know about gravity, it will be a serious undertaking. I recommend you learn a good deal of calculus to prepare for special relativity, and then move on to general relativity, preferably at a university, where it would probably be easiest. This will involve learning rather a lot of mathematics. Studying physics or applied mathematics would probably help to develop some level of physical intuition which would be of valuable assistance.

    It may seem like I have over-stated the gravity of the undertaking (pun intended) that is required to study the subject, but it will occupy a large portion of your time (or some suitable slice of some hypersurface...)

    EDIT: If you have the ability and time, you can also self-learn from some very good books on the subject. Others can offer better references than I could, so I shall leave it to them.
    Last edited: May 25, 2006
  4. May 26, 2006 #3
    This never happens.

    There's a difference between a quantitative theory and a qualitative one. Einstein's general relativity specifically says

    [tex]G_{ab} = 8\pi T_{ab}.[/tex]

    No matter what you write about gravity being "two like objects on the same frequency that happen to run into each other," in the equation above, the symbols have meanings, and lead to 6 independent coupled partial differential equations. If one solves them (assuming one has the correct mathematical methods), one gets numerical predictions about things like orbital periods, equations of motion etc. and we can directly compare these numbers to the real orbital periods. If these numbers agree better than any other previous theory, we have a contender for a new theory of the phenomenon. This is exactly what happened.

    As for your, "Why does one need to know math to understand a theory?" In your posts, you clearly demonstrate that without the mathematics, you will not be able to convey clearly what you mean.

    You also demonstrate your lack of knowledge of current physical theory, which already explain many of the phenomenon you wish to describe to unprecedented levels of accuracy. i.e. unless your theory makes predictions which matches experiment better than the ones we have, then your theories of the universe must be incorrect. It is that simple.
    Last edited: May 26, 2006
  5. May 26, 2006 #4
    Ahhh, I see. That's where the problem is. If a there is a question about the universe, that in principle, can never be resolved (or answered), then that is not physics, that is philosophy/metaphysics. If the question can be answered, then it is physics.

    I have not the time nor inclination to discuss philosophy on the internet, and this will, I imagine likely be the end of my participation in this discussion.

    As a final afterthought, I recommend you read about Newton's laws, if you don't know them. If you do, try reading about electromagnetism, or if you know that, try either special relativity or quantum mechanics. You will see that the real beauty in physics is that the "how much" often tells us, when correctly understood, the "how so" itself and we don't need a separate explanation of "how so".
  6. May 26, 2006 #5

    Doc Al

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    Staff: Mentor

    This thread was mistakenly moved to Independent Research. I'm moving it back, and deleting (for the last time) usp8riot's personal theories about gravity.

    usp8riot: I strongly urge you to take masudr's advice and start learning about physics from the beginning--starting with Newton's laws--before attempting your own explanations. Be prepared for quite a journey.
  7. May 26, 2006 #6
    It was only a theory and I clearly stated that. Some people here reply with unproven methods and don't get deleted. First off, I am aware of Newton's law and atleast basic physics. And my theory clearly doesn't refute those laws. It was a ground up theory and worked with the fundamental laws of physics. All truth has to start at a theory. Why do you rule out new theories? Even if it's personal hypothesis'. Why single out the knowledge or opinions of others? I've had no one yet who can dispute my theory, and was looking for someone. If not because I want to share my knowledge, but gain knowledge if told I'm wrong and how.
  8. May 26, 2006 #7

    Doc Al

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    Staff: Mentor

    Seems to me that your question "How does gravity work?" was just an excuse to discuss your personal theory.
    We don't "rule out" new theories. In fact, we have a forum (Independent Research) dedicated to just such efforts. Take a look at the threads in that forum. But there are minimum requirements for acceptance into that forum: verbal handwaving will not do.
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