# Correlating Newtonian Model with Einstein's GR

Discussion in 'Alternative Theories' started by hansda, May 8, 2017.

1. ### NotEinsteinValued Senior Member

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You effectively set it to infinity. If you say "all speeds are below 100m/s", then how can c (a speed) be its official value? It's effectively infinity in that model.

It's hand-wavy, yes, but obviously it works, since the maths check out.

And perhaps you should do that more often. I may be wrong in the details sometimes, but you've been wrong overall all this time.

My argumentation may be all over the place, my conclusions weirdly are always the same. I don't consider that "fickle minded".

By the way, I'm still waiting for you to point out any mistakes in the mathematical derivation of Newtonian physics from GR.

Indeed, reality does and has. If a choice has to be made between Newtonian physics and GR, GR wins hands down.

Have you already forgotten about those experiments we mentioned earlier? They give the value of G just fine.

Perhaps you should read an introductory text to GR. You've been talking about GR quite a lot now, but it seems you are missing the most basic understanding of it. What bends is spacetime.

Coupling strength, strength of the interaction. You know, the constant of nature that turns up as a multiplicative factor in the gravitational force in Newtonian physics. It's like turning a knob to set the strength of gravity.

In actuality it is you how needs to study up on the basics. You didn't even know what bends in GR. You can't even do any of the maths involved. You don't understand the process of limit taking.

I strongly suggest you do the same. You might even learn something!

3. ### SchmelzerValued Senior Member

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I cannot do physics without metaphysics.

If one tries to make a split using Popper's criterion, you will observe that it does not really work. Because to make a real testable prediction, you need a lot. At least the whole theory. In reality, even much more, in particular all the theory you need to make a claim about the accuracy of your measurement devices. The logical structure of the problem is quite simple: A and B gives a testable prediction. A alone not. B alone not. Are A, B, metaphysical or physical claims?

So, in Newtonian theory you make predictions using force. Is there a version of NT not using forces? Maybe, nobody cares. For the Einstein equations of GR in harmonic coordinates, there are two different interpretations, one with forces, one without. To consider the Newtonian limit of GR, and to compare it with NT, it makes sense to use the interpretation with force.
The results of this experiment can be predicted in GR as well as in NT. So, your "cannot be recognised" makes not much sense for me.

Of course, given that the preferred frame - even if it appears in the ether interpretation - is not directly measurable, one has, in GR, a problem with measuring everything related with the preferred frame. But this problem disappears in the weak field small velocity limit, because in this limit you can ignore time dilation, thus, clocks will measure, approximately, absolute time. Or, in the other direction, you can use what is measured with clocks as absolute time, without obtaining some sort of twin paradox or so. And you can use Einstein synchronization as if it would measure absolute contemporaneity.

5. ### NotEinsteinValued Senior Member

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(I think there's a strong case to be made forces aren't fundamental and perhaps can be done away with entirely in Lagrangian mechanics.)

7. ### The GodValued Senior Member

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Can you please, link me to some literature where GR is interpreted with gravity as force in it? (Not the alternative stuff pl)

8. ### SchmelzerValued Senior Member

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No, this is simply part of my alternative interpretation. In the mainstream, only the spacetime interpretation exists, to think about other interpretations is anathema.

Ok, not completely, google for "field theoretic approach" to GR, which is sufficiently mainstream. In this approach, you use a decomposition $g^{\mu\nu} = \eta^{\mu\nu} + h^{\mu\nu}$ where $\eta^{\mu\nu}$ describes a Minkowski background and $h^{\mu\nu}$ the gravitational field, so that the influence of $h^{\mu\nu}$ on whatever can be named a force. This goes back to Feynman. A guy with strong enough position not to care about anathemas. But I doubt you will find much.

The God likes this.
9. ### The GodValued Senior Member

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We??
Who are your partners in this song and dance? I see none, and btw forget gravity and GR, first learn to speak for yourself.

And I do not recall you mentioning any experiment, it was me who referred to Cavendish etc to make a point that these measurements are based on force and torsion etc, not based on spacetime bending. Anyways leave it, I know you will come up with some other theatrics, like introducing (irrelevant here) Lagrangian Mechanics.

Go back to trolling Hansda, yeah why Hansda misled you? That's what you asked him? Right?

10. ### SchmelzerValued Senior Member

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I doubt. In classical mechanics, you have the Lagrangian formalism of the form $L = m v^2 + V(q)$. In this case, the derivative of V is the force. What would be the point of getting rid of it?

11. ### NotEinsteinValued Senior Member

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I was using “we” as “we who are currently participating in this thread”. In hindsight I shouldn’t have done that, seeing as it confused you.

I also referenced them in my posts #84 and #95. It seems I’m not the only one that can be accused of not reading.

The results of the experiment can be interpreted based on force, yes, but also as based on the bending of spacetime. Please explain why these experiments cannot be explain in such terms.

I disagree. A version of Newtonian mechanics that isn’t fundamentally based on forces is quite relevant here, according to your continued insistence that forces are somehow needed to explain gravity.

To the best of my knowledge I wasn’t trolling him. Please report me if you think I was.

And when are you going to point out the mistake(s) in the mathematical derivation of Newtonian physics from GR?

12. ### arfa branecall me arfValued Senior Member

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Wow, all that typing and The God still hasn't been moved by any of it (!?). I would suggest that engaging him in any way is probably a complete waste of time.

13. ### The GodValued Senior Member

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That's unwarranted rudeness, can you pin point which post of mine is erroneous?

14. ### The GodValued Senior Member

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Oh you lie also; where did I say forces are somehow needed to explain gravity?

15. ### arfa branecall me arfValued Senior Member

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That's unwarranted irony, pal. But That's Your Thing, right?

16. ### The GodValued Senior Member

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Pl explain in your bending of spacetime interpretation what do you measure to get G?

You do not even understand that measuring bending of light around Sun itself is so difficult and so minute, and you wish to measure it in your Lab experiment.

Reading here and there will not take you anywhere, because you lack fundamental understanding of the subject. That's abundantly clear when you naively suggested doing away with force in Lagrangian Mechanics, as if that is some new Physics without force.

17. ### The GodValued Senior Member

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I though you were a nice bloke; mostly into self created threads. It will be useful if you pin point problems in my argument, otherwise I suggest you stay away.

18. ### NotEinsteinValued Senior Member

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For starters, you were claiming that the Cavendish experiment (which measures gravity) can only be explained by a force. Are you now saying it can be explained in other ways too?

Take the limits to weak gravity and slow speeds, dropping higher orders contributions, re-write your formulas into potential form, perform the Cavendish experiment, and done!
Another way I see would be to go with the Schwarzschild metric and calculate the orbit of a test-mass a distance of 1 AE away from a solar mass object, and compare to our solar system.

These are obviously not the most optimal way, but they work.

You do know testing gravity is rather simple, right? Take a pen, hold it (say) a meter above the ground, and let it go.

Actually, that probably would be a pretty good way to measure G.

At least I'm "reading here and there".

If so, that makes two of us.

And it's abundantly clear you have no idea what you are talking about. Lagrangian Mechanics is not "some new Physics", and I never claimed such. Please stop putting words in my mouth.

And again, when are you going to point out the mistake(s) in the mathematical derivation of Newtonian physics from GR?

19. ### The GodValued Senior Member

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So you do not understand the entire argument....you are just misquoting me on everything.

Let me revisit you to #62 and #67...which talks of GR and Newtonian being conceptually two different theories, and it is made up to claim that GR reduces to Newtonian in limiting case.

Again you misquoted me on Lagrangian, it was your claim of doing away with force, suggesting new physics, I just negated that. But you admitted your argument is either everywhere or sloppy or hand wavy. Keep dancing.

20. ### The GodValued Senior Member

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1. You give a link on Laplace without reading, and when pointed out you casually withdrew.
2. Then you talk force as something of spacetime, and again back out.
3. Then you claim taking c to infinity and when objected you admitted hand waving.
4. Then you talk of Lagrangian as fundamentally doing away with force and again you back out.

One thread, 4-5 back outs...that's record sort of. Back out is still ok, that's ignorance, but attributing things to me which I never said is pure dishonesty. Take care.

21. ### originHeading towards oblivionValued Senior Member

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Your posts in this thread, as always, can be summed up as 50% arrogance and 50% ignorance against a background of anti-science.

You just like to argue and annoy, but after this much time you are just sort of a white noise on the site that gets blocked out.

22. ### The GodValued Senior Member

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Pl attempt questions in #62 and #56.

23. ### originHeading towards oblivionValued Senior Member

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I just noticed that The God has been permanently banned. That is a good thing for this site IMHO.

Last edited: Oct 10, 2017