# Correlating Newtonian Model with Einstein's GR

I am not talking about natural units. You have understood that G and 8pi G both have same units, so why only 8 piG why not G or 100000G or why not 0.0000001G?
Erm, because 8pi is the right value, and 100000 and 0.0000001 are not?

Even this will take you to Newtonian.
What do you mean by that exactly? If you mean that using those other values instead of 8pi also will lead to Newtonian physics, you would be incorrect: the resulting formulas would be similar, but off by various constant factors. In other words, you do not end up with Newtonian physics.

Erm, because 8pi is the right value, and 100000 and 0.0000001 are not?

What do you mean by that exactly? If you mean that using those other values instead of 8pi also will lead to Newtonian physics, you would be incorrect: the resulting formulas would be similar, but off by various constant factors. In other words, you do not end up with Newtonian physics.

You did not get, your dimensional analysis is true with any dimension less constant, if you find why 8pi, then it will lead you to Newtonian.

You did not get, your dimensional analysis is true with any dimension less constant, if you find why 8pi, then it will lead you to Newtonian.
The only explanation I've been able to find so far is that it's 8pi because then it leads to Newtonian physics; it's a normalization of the theory in the Newtonian limit.

I find that explanation quite unsatisfying. Anybody know of a better, more fundamental explanation?

But that's actually neither here nor there. Your original comment was:
The claim that limiting case of GR is Newtonian is bad, because both are conceptually different, buy it is used to give legitimacy to flicking 'G' from Newtonian.
This has now been conclusively debunked by the link to that derivation I gave above. You can only argue that the choice of normalization is arbitrary, but it obviously matches what we see in nature. We can perhaps not derive it from the equations themselves, so we call it a "constant of nature" (for now).

In fact, that's exactly what happens in Newtonian physics with G. It's just a normalization parameter of the model that we set to a value to make the theory give answers that match reality.

I will wait for answer to your question in the first part of your above post. More or less you have hit the Bull's eye, quite close.

I will wait for answer to your question in the first part of your above post. More or less you have hit the Bull's eye, quite close.
Ah, so you now agree with me that one can derive Newtonian physics from GR. Good. Going back on topic: what's your opinion on hansda's claim that his text correlates Newtonian physics with GR?

In fact, perhaps hansda can explain to us where this factor of 8pi exactly comes from!

Ah, so you now agree with me that one can derive Newtonian physics from GR. Good. Going back on topic: what's your opinion on hansda's claim that his text correlates Newtonian physics with GR?

In fact, perhaps hansda can explain to us where this factor of 8pi exactly comes from!

No, no....but if that pleases you after you made lot of dramatics in last few posts.

You read my first post again and get back what I said.

No, no....but if that pleases you after you made lot of dramatics in last few posts.
So you have found a mistake in the derivation I posted a link to? Please point me to it!

You read my first post again and get back what I said.
Ok:

There is a forced connection between the two.
Well, both have to actually describe reality; their answers have to be right in order for the model to be useful. If you call that a forced connection, then yes.

If you get into details of GR equations, then the obvious question you can ask is where does 'G' come from in those equations?
This is clear: there has to be a constant there, because of dimensional analysis. The value cannot be derived from the theory (unless somebody can demonstrate otherwise), so we have to select some value that makes it match what we see in reality. This constant happens to match 8piG, so instead of inventing another constant, we simply write 8piG. Quite straight-forward, if you ask me.

It is actually thanks to Newtonian.
Incorrect; it's due to reality.

The claim that limiting case of GR is Newtonian is bad, because both are conceptually different, buy it is used to give legitimacy to flicking 'G' from Newtonian.
This I already responded to in post #43.

Now would you please respond to the question I asked you in post #45?

So you have found a mistake in the derivation I posted a link to? Please point me to it!

Ok:

Well, both have to actually describe reality; their answers have to be right in order for the model to be useful. If you call that a forced connection, then yes.

This is clear: there has to be a constant there, because of dimensional analysis. The value cannot be derived from the theory (unless somebody can demonstrate otherwise), so we have to select some value that makes it match what we see in reality. This constant happens to match 8piG, so instead of inventing another constant, we simply write 8piG. Quite straight-forward, if you ask me.

Incorrect; it's due to reality.

This I already responded to in post #43.

Now would you please respond to the question I asked you in post #45?

I am not speaking in support of Handsa, so I cannot say anything about him.

Before you continue with your song and dance, why don't you seek answer for the question you raised in your #43.

You do not even understand that both GR and Newtonian are conceptually different, still support the view that GR in limiting case gives Newtonian. This was a forced necessity to flick G not your funny dimensional analysis excuse. Ok, I will give you one more hint ...list down three differences between GR and Newtonian.

I see you've ignored the first part of my post. May I conclude you actually haven't found a mistake in the derivation I posted, and that it thus is a good example of how Newtonian physics can be derived from GR?

I am not speaking in support of Handsa, so I cannot say anything about him.
So you haven't read his text, where he (allegedly) makes the connection between GR and Newtonian physics?

Before you continue with your song and dance, why don't you seek answer for the question you raised in your #43.
You haven't bothered to read hansda's text, so you are also guilty of this.

And I actually have been looking for this; I just haven't found it. And clearly, you don't have an answer either.

You do not even understand that both GR and Newtonian are conceptually different,
Please refrain from making unfounded assumptions about what I understand and what I don't. Even if they are conceptually different, that doesn't mean you can't derive one from the other.

still support the view that GR in limiting case gives Newtonian.
You have shown a complete lack of arguments in support of the claim that it doesn't. In fact, you've dodged that question in this very post of yours.

Please give an argument as to why the derivation I linked is incorrect.

This was a forced necessity to flick G not your funny dimensional analysis excuse.
"My" funny dimensional analysis? Please look it up; it's a well-establish principle in science, so it's not mine. But please explain to me why dimensional analysis is an "excuse".

Ok, I will give you one more hint ...list down three differences between GR and Newtonian.
No, you are the one claiming they are different; the burden of proof is on you. You list three differences between GR and Newtonian physics.

Ok, they are same, if that pleases you and you can conclude anything you like. "Shrug"

Ok, they are same, if that pleases you and you can conclude anything you like. "Shrug"
I never said that. Please stop putting words in my mouth.

Ohhhh, some popsci article. Good you can entertain yourself.

I never said that. Please stop putting words in my mouth.
The God acts like the classic anti-science troll, he likes to argue from a position of ignorance. Waste of time...

I never said that. Please stop putting words in my mouth.

So what's your point? What are you opposing?

Anyway, find out the answer of these questions for yourself...

True or False questions for you.

1. Newtonian theory has nothing to do with geometry of spacetime.
2. GR is about geometry of spacetime.
3. In GR, the gravity is not a force.
4. In Newtonian the gravity is a force.
5. In GR the speed of gravity is c.
6. In Newtonian the speed of gravity is infinite.

Last Hint : actually Newtonian was used to get G (and other factors in GR), because Newtonian was and still the reality in general usages.

The God acts like the classic anti-science troll, he likes to argue from a position of ignorance. Waste of time...
Judging on his/her behavior in the last couple of posts I get that feeling too, but I'll just engage him/her as (s)he is, and let the moderators worry about it.

The God acts like the classic anti-science troll, he likes to argue from a position of ignorance. Waste of time...

Oh, so origin, contribute pl. Back to one liners?

Why not attempt questions in #56. Let me see what you know.

Judging on his/her behavior in the last couple of posts I get that feeling too, but I'll just engage him/her as (s)he is, and let the moderators worry about it.

No, except two less than upto the mark links, your argument is nothing but follow the authority.

You are still confused why 8piG.

So what's your point? What are you opposing?
My point is that hansda misled me when he said that his TOE explained the connection between Newtonian physics and GR.
My other point is that Newtonian physics can be derived from the theory of relativity.

Anyway, find out the answer of these questions for yourself...

True or False questions for you.

1. Newtonian theory has nothing to do with geometry of spacetime.
False. Originally of course it wasn't brought up, but then the theory of relativity showed us about the geometry of spacetime, and we started interpreting Newtonian theory in that light too.

2. GR is about geometry of spacetime.
True, though perhaps not solely.

3. In GR, the gravity is not a force.
True.

4. In Newtonian the gravity is a force.
True.

5. In GR the speed of gravity is c.
True.

6. In Newtonian the speed of gravity is infinite.
Unclear. Often it's taken as such, but I don't think it's a requirement of it. The limited speed of gravity was known well before the theory of relativity came along, and I don't remember scientists claiming this debunk Newtonian physics.

Last Hint : actually Newtonian was used to get G (and other factors in GR), because Newtonian was and still the reality in general usages.
But that has no bearing on whether one can derive Newtonian physics from GR. In fact, it signals the two are connected, in that in specific cases Newtonian physics is "good enough". I.e., GR is a more general case of Newtonian physics.