Gravitation

Discussion in 'Physics & Math' started by Aer, Aug 27, 2005.

  1. Aer Registered Senior Member

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    Let's review. I never said matter. I said just as you quoted You said this notion comes up in the theory based on the assumption that all energy contributes. Are you now claiming that all energy is matter? You are wrong again.
     
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  3. Physics Monkey Snow Monkey and Physicist Registered Senior Member

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    Too bad you didn't also quote the next sentence where I say, "You don't even have to mention the word energy." I never claimed that you said the word 'matter'. My simple point was that curvature can exist without more traditional forms of mass-energy, i.e. even if the stress-energy tensor is zero. If you need to think that curvature makes magic curvature energy to understand how curvature can exist even when the stress-energy tensor is zero, then go right ahead. However, note that gravity has no stress-energy tensor so magic curvature energy is somehow a bit more strange than other forms of energy i.e. can't be localized.
     
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  5. Aer Registered Senior Member

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    You are claiming it comes 'from the mathematics' when in fact there is always a physical meaning to the mathematics. Do you know what the physical meaning is? And by the way, physical does not mean the mathematical model that describes physics. Physical is the tangibles. The simple matter is that all curvature in GR in assumed to be cause by -energy-. The result that curvature compounds on itself is the result of curvature creating energy - see? No, of course you don't - you are going to go back to your warm fuzzy tensor mathematical model and not talk about anything physical and thus not mention the word 'energy'.
     
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  7. Physics Monkey Snow Monkey and Physicist Registered Senior Member

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    Aer, I'm a physicist. The physical world is my playground. What do you do? Apparently, your self-assigned task in this world is to jabber nonsense and shout insults on internet message boards.
     
  8. Aer Registered Senior Member

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    Apparently you are not very good at describing this physical world if you have to refer to tensors and other mathematical concepts as the "physical understanding".

    Nothing I've said is nonsense - I am merely asking you to decribe physically the nature of curvature of spacetime as described by GR. When I say physcially, I mean just that. The mathematical analysis is always good too, but it is not a pure substitute to the physical situation, specifically when Pete and I have been discussing soleing the physical nature (with the exception of feedback stuff).
     
  9. Pete It's not rocket surgery Moderator

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    Fine.

    Think of M as Mass, X as curvature, and Y as energy bound in the system. (This is a proof-of-concept simple analogy only. The true relationships are obviously more complex.)

    X is caused by both M and Y as follows:
    X = (M+Y)/10

    X causes Y, but not M:
    Y = X
    M is constant.

    M starts at 100, Y starts at zero, giving an initial X of 10.

    Following it through you'll find that it balances at X = Y = 10/9
     
  10. Aer Registered Senior Member

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    If I am interpreting you correctly (based on your presentation here and you presentation in the stability thread) then you are analyzing this as a discrete system. I stated before that I do not think it is appropriate in this situation to treat it that way. It in fact is a continuous model is it not? I think we need to establish the difference between a discrete system and a continuous system. While discrete systems are sometimes used, continuous systems are much more preferred because the mathematical model is much nicer when you get into more complex situations and analysis. And if you wanted to do a discrete system, you would have to first figure out how to transfer the information to a discrete model which I for one am not familar with. Perhaps SL has more knowledge on discrete systems.
     
  11. Pete It's not rocket surgery Moderator

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    Aer, I'm simply responding to your post:
    Can you please explain why your treatment of the system as discrete is appropriate, while mine isn't?
     
  12. Aer Registered Senior Member

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    Neither of us is correct in treating it as a discrete system. I said awhile back
    The both of us are in error trying to treat it as a discrete system..
     
  13. Pete It's not rocket surgery Moderator

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    Right, well we can go back to before you introduced your erroneous sidetrack:
     
  14. Aer Registered Senior Member

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    What erroneous sidetrack? I stated that such a thing (if it was actually positive feedback) would continuously increase. I still think that is true.

    If you wish to start over, I think we should start with the question about the nature of gravitational binding energy. My understanding would say that is a negative quantity and kinetic energy counters it. If an object such as the Earth had kinetic energy greater than the gravitational binding energy of the sun, then the Earth could escape the Sun's gravitational pull. But it is kind of vague what escaping such a pull really means since all objects give a gravitational binding energy that extends to infinity.

    So would it be appriopriate to state that the Earth has escaped the Sun's gravitational pull at the moment it's kinetic energy exceeds the gravitational binding energy?
     
    Last edited: Sep 16, 2005
  15. Pete It's not rocket surgery Moderator

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    The one you just said was incorrect - this one, remember?
    The question we were attempting to resolve when we were sidetracked by that post was whether or not it is ridiculous for some "X" for to be the effect of some "Y" and also to produce more "Y".

    Your position was that yes, it is ridiculous. Do you still maintain that position?
     
  16. Aer Registered Senior Member

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    Well, if you are agreeing with me that that type of analysis is incorrect, then you have to accept the other side of the coin which is that your analysis was incorrect as well.
    Depends on what it is meant by ridiculous. I say that such a thing would increase to infinity which is why I say it is ridiculous. You say that such a thing has a physical limit which you've yet to prove and I have tried to help you prove by switching it to negative feedback, but thus far you have insisted that it be positive feedback.

    Yes, as long as you are maintaining that it is positive feedback. I am unsure of what we will get with negative feedback though.
     
  17. Pete It's not rocket surgery Moderator

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    At least my analysis was a correct discrete analysis

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    Right, this is where we differ - hence the *theoretical* discussion in the other thread.
     
  18. Aer Registered Senior Member

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    How can you differ? You are claiming such a thing is reality. I suppose all my claims are equally correct in reality

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    I am going to claim that Pete's head just imploded. Did it happen?
     
  19. Pete It's not rocket surgery Moderator

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    Don't be an idiot.

    I'm claiming that it would not necessarily increase to infinity.

    You cited control theory as proof of your claim that it would necessarily increase to infinity, which is why we're examining that theory in the other thread.
     
  20. Aer Registered Senior Member

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    Are you claiming "gravity waves" move faster than the speed of light, essentially instantanaeously in the strictest meaning of the word "instantaneous" meaning, absolute 0 delay. That is not the accepted theory as far as I know it.

    If you accept that gravity works in such a manner, then I will accept that you would have to accept that everything is okey dokey.
     
  21. Pete It's not rocket surgery Moderator

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    Yes, I'd like to progress to the non-zero delay case, but unfortunately you're bogged down in the zero-delay case.

    When we get it sorted out, perhaps we can move on.
     
  22. Aer Registered Senior Member

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    OK, the non-zero delay case is not described by your "ideal amplification" case.
     
  23. Pete It's not rocket surgery Moderator

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    No shit, sherlock!

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    Come over to the other thread so we can progress.
     

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