Gravitation

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

1. AerRegistered Senior Member

Messages:
2,250
Nothing I've stated concerning feedback is hot air.

Everything I've stated is mere mathematical definition or results from mathematical theory such as 1/0 is undefined and such. So what are you talking about? What exactly in control theory is arrived from assumption?

Are you comparing General Relativity which inherently assumes postulates to Control Theory which is a result of mathematical application? What are the postulates involved in Control Theory - what assumptions are made to arrive at the results?

You clearly do not know what a pole is. Here is a crash course on zeros and poles. Zeros are in the numerator and can be found by setting the numerator equal to ZERO. The reason they are called 'zeros' is because they are solutions to which function will be... guess... yes, ZERO. Now a pole is when the denominator is... take a guess, ahh yes, ZERO. Note that when the denominator is zero that the function is not zero, but undefined. These are called "poles". So yes, setting (1-GainxFeedback) = 0 will give GainxFeedback=1, i.e. a postive pole at 1. Are you sure you understand what a pole is yet?

3. AerRegistered Senior Member

Messages:
2,250
Obviously limited knowledge of control theory? Are you suggesting that you know more? Please, provide you knowledge on Control Theory.

I've told you my position on curvature creating more curvature - it is not a very sound proposition as even James R seems to think, but it is hard to tell because he has been waffling all over the place on the subject of gravitational binding energy contributing to the curvature of spacetime.

5. AerRegistered Senior Member

Messages:
2,250
And also cause more "Y" and also cause more "Y" and also cause more "Y" and also cause more "Y" and also cause more "Y" and also cause more "Y".

When does it stop and why?

What do I accept? I certainly do not accept that kintetic energy contributes to the curvature of spacetime or that gravitational binding energy contributes to the curvature of spacetime curvature unless I have a good reason to believe so - which by the way, would be direct evidence that this must be the case. For the record, I do not accept either claim - that is the claim you make and the claim that I make. There is no evidence for either, but I do have to say, that your arguments thus far have created major holes in your claim.

7. PeteIt's not rocket surgeryRegistered Senior Member

Messages:
10,166
Proof by assertion. Lovely.

Oh, please - I cast no aspersions on control theory, just on your ability to apply it.

Thank you for such an enlightening exposition.

Now, let's see you apply it.

You are given that:
Gain = 2
Feedback = 0.2
These values are inherent to the system described.

Now, how exactly do propose to set (1 - Gain x Feedback) to zero, when it is clearly equal to 0.6?

Last edited: Sep 16, 2005
8. PeteIt's not rocket surgeryRegistered Senior Member

Messages:
10,166
When the increment diminishes to zero.
1 + 0.5 + 0.25 + 0.125 + ...

Or, if you prefer a continuous model, try integrating an appropriate function to infinity. You're not claiming that no such integral is finite, are you?

9. PeteIt's not rocket surgeryRegistered Senior Member

Messages:
10,166
Well, I thought you accepted that its not ridiculous for some "X" for to be the effect of some "Y" and also to produce more "Y"...

But you really don't, do you?

10. AerRegistered Senior Member

Messages:
2,250
This is where your system is not fully defined because while your Gain is 2, the gain mechanism will be described as 2/s as I told you elsewhere. But it doesn't have to be 2/s, it could be 2/s^2 or 2/(s+s^2) or something else depending on the differential equations that describe your setup.

Messages:
10,166

12. AerRegistered Senior Member

Messages:
2,250
A finite integral for infinite bounds is only defined when the function being integrated decays at a certain rate. What is the rate at which what we are describing would decay?

13. AerRegistered Senior Member

Messages:
2,250
Try to think this one through, if X starts out at 10, and Y was 1/10 of X, then Y+X=11, then we have 11+1.1, then 12.1+1.21, then 13.31+1.331 - I don't see this converging anytime soon. Can you describe mathematically what your X is and what your Y is as it relates to curvature of spacetime and gravitational binding energy?

Furthermore, why is curvature of spacetime adding upon itself when gravitational binding energy is negative I would think it would be the other way around, that is curvature of spacetime subtracting from itself.

14. Physics MonkeySnow Monkey and PhysicistRegistered Senior Member

Messages:
869
Aer, the question of whether or not curvature contributes to itself in GR is not open for discussion. It is not a matter of opinion, and the fact that you personally can't understand why based on your rudimentary knowledge changes nothing.

15. AerRegistered Senior Member

Messages:
2,250
It is too open for discussion, I am discussing it! You can butt out if you don't have the knowledge to discuss it.

Your reference to opinions has no basis. It comes up in the theory based on the assumption that -all energy- contributes to spacetime curvature. I just proposed an assumption that mass-energy is in fact the energy that contributes to spacetime curvature.

16. Physics MonkeySnow Monkey and PhysicistRegistered Senior Member

Messages:
869
Hardly. Just one more reason why you don't know what you're talking about. I can solve the Einstein field equations without matter so that you're feeble excuse is irrelevant. You know what I find? Nontrivial curved space solutions even with no matter present. It is a simple mathematical fact built into the structure of GR that curvature, with or without matter, acts as a source for itself.

17. PeteIt's not rocket surgeryRegistered Senior Member

Messages:
10,166
Ah! I see where you're confused now!

X doesn't start at 10, X starts at zero.
M starts at 10.

Y is caused by both M and X:
Y = (M+X)/10
Y produces X, but not M:
X = Y
M = M

M starts at 10, X starts at 0.

You'll find that it balances at X = Y = 10/9

Analogizing, you could think of M as Mass, Y as curvature, and X as energy bound in the system.

That's something we can consider when we've resolved whether or not it's ridiculous for X to be the effect of Y and also cause more Y.

18. AerRegistered Senior Member

Messages:
2,250
No, X is the curvature of spacetime. For any given object, X DOES NOT start at 0. Any object has mass-energy which we all agree contributes to spacetime curvature.

True but X is caused by M which you mistated above.

So start over.

Edit: It does appear that we are not referring to X and Y as the same thing.

Last edited: Sep 16, 2005
19. AerRegistered Senior Member

Messages:
2,250
Now you are saying that curvature of spacetime is not assumed to be caused by all energy. Good Job. So which energies do not contribute to spacetime curvature?

20. Physics MonkeySnow Monkey and PhysicistRegistered Senior Member

Messages:
869
Nope, I said curvature generates curvature regardless of rather mass-energy is there to help. Of course we all know that mass-energy contributes to curvature as well.

21. AerRegistered Senior Member

Messages:
2,250
I think it would be a good idea to resolve this first, because in one case you'd be dealing with positive feedback and the other case you'd be dealing with negative feedback. Furthermore, we are still trying to do discrete analysis which is not appropriate for the situation here. You would do discrete analysis if you were taking samples of the model, but the model is fundamentally continuous.

22. AerRegistered Senior Member

Messages:
2,250
No, you said "Hardly" when I said that in GR all energy is assumed to contribute to spacetime curvature.

23. Physics MonkeySnow Monkey and PhysicistRegistered Senior Member

Messages:
869
Let us review. I said, curvature contributes to curvature. You said this notion comes up in the theory based on the assumption that all energy contributes. I said, hardly. The notion that curvature contributes to curvature has got nothing to do with rather matter contributes or not. I don't even have to mention the word energy.

Sorry, you are wrong again.