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Gravitation: Curvature- vs -particles

  1. Feb 8, 2013 #1
    On occasion I notice there is some talk about "graviton" particles, I would have thought astro/ quantum sciences were past that idea. I am quite aware of a basic rule "Don't fall in love with your theories" so a gravity particle might exist, more on that later.

    In my understanding of relativity, Einstein doesn't prove or disprove Newton's laws, but he pointed out that the laws were limited to the restrictive "special" theory. This also leads to the concept of gravity as an "apparent" field, and in this sense Newton was confined due to the limited technology of his time, as well as his reference body seemed to be at rest. it is easy to see how gravity would have shown signs of it being similar to electro/ magnetism.

    One problematic issue of the field theory, is that magnets attract certain metals, but not wood, stones or other materials. Gravity does not discriminate. it would also occur to me that the massiveness of our sun would generate a field (no matter how weak) that should be large enough to attract the inner planets directly into the sun itself. Also if a gravitational field similar to electro-magnetism should not be conducive to the creation of orbit, orbit gives the impression that there is a struggle between an attractive and repulsive forces at work simultaneously. A curved and warped continuum could create those circumstance

    I think a more accurate consideration is that a plastic and pliable universe might cause gravitation independent of a fields.

    in my opening paragraph I stated there is a chance of gravity particles, so looking at the opposite side of this matter. The monkey wrench of dark matter/ energy thrown into this mix, resurrects a particle theory and might give an optional outlook other than curvature. The indirect proof of dark matter/ energy can be seen in the case of cosmic lensing. To that end the phenomenon of barely detectable substance, that has no mass or interaction with other particles but creates gravity, gives way to see a probable "graviton" from a fresh point of view.

    finally there is a point and a question to my rambling. Could dark matter/ energy be the missing gravitation particle? Or are these W.I.M.P. ('s) the basic substance of space that appears to be empty?
  2. jcsd
  3. Feb 8, 2013 #2


    Staff: Mentor

    This isn't quite right. According to relativity, Newton's laws are only approximations, valid when speeds are very slow compared to the speed of light and gravity is weak. The special theory of relativity deals with speeds that are not slow compared to the speed of light, but does not include gravity. The general theory of relativity adds gravity, including cases where gravity is not weak.

    Are you referring to relativity or to Newton's theory? In Newton's theory, gravity is a "real" force; it is not "apparent". In general relativity, gravity is not a force at all; it is a manifestation of spacetime curvature.

    This is true, but I don't understand why you think it's problematic.

    Why do you think this? Gravity is certainly "conducive to orbits"; why do you think it isn't?

    This, along with most of the rest of your post, looks like personal speculation, which is not allowed in this forum (see the forum rules); this forum is for discussing special and general relativity. However, you do end up with two valid questions:

    No. The graviton is the quantum aspect of gravity, which means it's the quantum aspect of spacetime curvature. To see that quantum aspect, we would have to probe spacetime on very, very short length scales, of the order of the Planck length (10^-35 meters). We are many, many orders of magnitude away from being able to do that, and the evidence we have for dark matter and dark energy is at much, much larger length scales. On those scales, spacetime is just spacetime; there's no particle aspect associated with it that we can detect.

    I'm not sure what you mean by "the basic substance of space that appears to be empty", but that's one way of describing what dark energy is--at least, on the simplest hypothesis. The simplest form of dark energy is a cosmological constant, which works like a nonzero energy density of the vacuum; see, for example, here:


    WIMP's are one possible candidate for dark matter, which is something different; it's like ordinary matter (i.e., it doesn't have the exotic properties that dark energy does, which are described briefly in the link above), but it doesn't interact by any of the non-gravitational interactions we know of (strong, weak, electromagnetic), so the only way we have of detecting it is by its gravity.
  4. Feb 9, 2013 #3
    no you are wrong. you can easily prove that its actually extremely hard to fall into the sun. indeed you can show that it is *easier* to leave the solar system than to fall into the sun, and all from Newtonian dynamics.
  5. Feb 10, 2013 #4
    The sun does attract planets in our solar system. But the instantaneous direction of attraction happens not to be toward the center of the sun.

    F = qE +qv x B so electric field attracts in the direction of motion, the magnetic field orthogonal to the direction of motion [creating an orbital type attraction].

    Einstein called such a curved warped 'continum' the curvature of space-time...that IS gravity.
  6. Feb 10, 2013 #5


    Staff: Mentor

    Actually, to order v^2/c^2, it is. There is a very small component of the interaction that is directed perpendicular to the instantaneous Earth-Sun line, but it is higher order in Earth's velocity relative to the Sun. So thinking of the attraction as directed towards the Sun's center is actually a very good approximation, even when relativity is taken into account. The reason the Earth doesn't fall into the Sun is that the Earth has enough tangential velocity to stay in orbit.

    (Note that this does *not* mean that gravity travels faster than light. It just means the gravitational interaction in relativity is more complex than just a force that depends on the inverse square of the distance with a light-speed time delay.)
  7. Feb 11, 2013 #6
    I had posted replies to every statement that was made, but by now I should no that the more I write directly on a web site, the higher the possibility of deleting that text. in other words, I didn't back up my writing on a writing app, so I will have to rewrite. there are a few points I need to make now. I made the mistake of posting without editing, and I probably should have added quotes and sited sources as well. I was vague throughout my post. it has been a while since I have written anything in a scholarly way for a while, and Facebook has made me lazy. Another thing I have to point out is I am not a scientist and have difficulty comprehending even the simplest equations or algebra, this doesn't mean I will ignore equations etc. it just means I will have to take more time and work harder in these situations than some people. I need to adress one specific thing. "I think a more accurate consideration is that a plastic and pliable universe might cause gravitation independent of a fields."
    "This, along with most of the rest of your post, looks like personal speculation, which is not allowed in this forum (see the forum rules); this forum is for discussing special and general relativity." I have read the rules, you should have read this rule "Personal theories or speculations that go beyond or counter to generally-accepted science" a little better before pointing it out. I really don't have any theories of my own, I haven't tried to counter or go beyond the scope of general relativity. I used the word "think" in the third meaning of the word " 3. vti comprehend something: to imagine or understand something or the possibility of something" (according to the dictionary associated with windows word processor) as I understand this rule, I believe it is made to exclude challenges to accepted laws and theories (consider this "I think that Einstein was stating that I a more accurate consideration is that a plastic and pliable universe might cause gravitation independent of a fields . . ." I am thinking about relativity and not a personal view. Also it says go beyond accepted science. an extreme example would be if I said "Einstein was given this knowledge by alien life forms" or some such crackpot statement. It is impossible for anyone to not personalize and/ or speculate in an absolute objective way. but that is a neurological and psychological discussion, and not a matter of relativity, my speculation might be dead wrong, but that is a lack of understanding and not a challenge. my reasoning to post on this site is to find out what I am wrong about. I will return to my notes and respond more specifically on other points, but only to say "I am wrong about that, thank you for pointing out my error", "I was vague on that point", or "you should use a thesaurus or dictionary when in doubt about certain words" (I use these types of text when I think my usage is incorrect because many words have multiple meanings) If I came off as being cocky I don't mean to, I am thankful for every response. after I make more specific replies I will no longer discuss this post. It was poorly written, unedited, and no quotes or reference to my Resources has been used.
    Last edited: Feb 11, 2013
  8. Feb 11, 2013 #7


    Staff: Mentor

    From your clarification, I understand better where you are coming from. Taken by itself (i.e., separated from other things you said in your original post, which had other issues that I pointed out in my earlier post), the statement I bolded above can be construed as saying that GR considers gravity to be caused by spacetime curvature, instead of by a "field". This is not wrong, exactly, but it sets up a contrast that is not really there, physically. It is better to think of "spacetime curvature" and "field" as two different interpretations of the mathematical equations of GR, not as two different physical ways the world could be.

    If you had stated it this way, it would have been easier to tell that you were trying to talk about general relativity, not a personal theory. (A still better way would have been to ask a question, like: "Is this a reasonable way to state what GR is saying?") The fact that your original post was phrased as a flat statement, without the "I think Einstein was stating...", and that it included other statements that had issues, was what triggered my "possible personal theory" detector.
  9. Feb 11, 2013 #8


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    Staff Emeritus
    Science Advisor

    Alas, writing isn't easy.

    My basic impression, though, is that when you write

    you've been doing more personal thinking and speculating than reading and looking up definitions when necessary. If you cite a peer reviewed paper that actualy uses this exact phrase "a plastic and pliable universe", I shall have to eat my words (but learning about it will more than make up for the embarassment).

    At the moment, though, I would guess that this phrase is your invention, but it's not obvious at all what spawned it or what it's even supposed to mean. The fact that it's your attempt to understand GR doesnt make it any less of a personal invention unless the phrase IS from the literature.
    Last edited: Feb 11, 2013
  10. Feb 14, 2013 #9
    I'll look into that thank you
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