Discussion:
A Newton-like description of gravity, representing curved space-time.
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Jan VR
2007-01-02 19:45:01 UTC
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Hi,

I tried to summarize my ideas on this website:

http://home.scarlet.be/~tsd53243/

Any comments or feedback would be most welcome.

Greetings,
Jan
Sorcerer
2007-01-02 22:18:57 UTC
Permalink
"Jan VR" <***@versateladsl.be> wrote in message news:***@h40g2000cwb.googlegroups.com...
| Hi,
|
| I tried to summarize my ideas on this website:
|
| http://home.scarlet.be/~tsd53243/
|
| Any comments or feedback would be most welcome.
|
| Greetings,
| Jan

Ok, here's some feedback. Answer this non-trivial question:
What is the value of c in your equations (5), (13), (16-20) and (23), and
how did you arrive at it?
("Everybody knows" is not an acceptable response in mathematics).
William D. Walker
2007-01-05 08:39:24 UTC
Permalink
Hi Jan,

I have came across a paper that may answer your question about how to
modify Newton theory so that it can also be applied to curved spaces. I
hope it helps. Let me know what you think of it. To access the paper
click on the following hyperlink:

http://folk.ntnu.no/williaw/Forward.pdf


R. Forward, ‘General relativity for the experimentalist’,
Proceedings of the IRE, 49, May (1961)
Post by Jan VR
Hi,
http://home.scarlet.be/~tsd53243/
Any comments or feedback would be most welcome.
Greetings,
Jan
Ken S. Tucker
2007-01-05 18:29:19 UTC
Permalink
Post by Jan VR
Hi,
http://home.scarlet.be/~tsd53243/
Any comments or feedback would be most welcome.
I recommend you read Einsteins original GR1916
article, "The Foundation of General Relativity", it's
concise, a bit dated, but it gives the reason for GR,
especially General Covariance.
What you have so far is ok from a beginners standpoint,
it's a good start (the notation in eq(21,22) is not std), but
you should consult some reputable texts on the subject.

You state you have a Ph.d in Nuclear Physics, then I
should ask, do you understand Planck's constant?
Regards
Ken
Eric Gisse
2007-01-05 22:18:08 UTC
Permalink
Post by Jan VR
Hi,
http://home.scarlet.be/~tsd53243/
Any comments or feedback would be most welcome.
Your PDF links do not work.
Post by Jan VR
Greetings,
Jan
sal
2007-01-06 15:13:25 UTC
Permalink
Post by Eric Gisse
Post by Jan VR
Hi,
http://home.scarlet.be/~tsd53243/
Any comments or feedback would be most welcome.
Your PDF links do not work.
They work for me, on 1/6/07.
Post by Eric Gisse
Post by Jan VR
Greetings,
Jan
--
Nospam becomes physicsinsights to fix the email
Jan VR
2007-01-06 17:17:46 UTC
Permalink
Hello,

Thanks for your comments. Here's my reply:

- to Sorcerer: c is the speed of light in vacuum: 299 792 458 m/s as
far as I know...

- to William: I wrote you an email with my comments.

- to Ken: I looked for the Einstein paper and found it on the web; I
will read it. I hope it contains the anwsers as to why the simple model
I used is incomplete. About Planck's constant: I know what it is and
what importance it has in Quantum Mechanics. But I do not really
'understand' it (as there are more things in QM which cannot be
understood...). Why do you ask ?

- To Eric: if you still cannot access the pdf's and if you are
interested, I can send them to you. Just let me know. But normally it
should work.

Cheers,
Jan
Sorcerer
2007-01-06 19:10:11 UTC
Permalink
"Jan VR" <***@versateladsl.be> wrote in message news:***@i15g2000cwa.googlegroups.com...
|
| Hello,
|
| Thanks for your comments. Here's my reply:
|
| - to Sorcerer: c is the speed of light in vacuum: 299 792 458 m/s as
| far as I know...

You don't know very far.
The speed of light in vacuum is 299 792 458 m/s +/- 1.1 m/s relative
to the source,
c = 0/0 and is not the speed of light.

Loading Image...
How far is it from A to A and how long will it take to get there?
Ken S. Tucker
2007-01-06 22:14:23 UTC
Permalink
Jan these are my comments, and do not
always reflect the views of the classical
GR community, for those a gadzillion books
and articles are available.
Post by Jan VR
Hello,
- to Ken: I looked for the Einstein paper and found it on the web; I
will read it. I hope it contains the anwsers as to why the simple model
I used is incomplete.
It's a no-brainer getting the Schwarzschild metric once
you know the answer, in fact it's rather easy to derive
from E =hv (Plancks photon energy equation), once you
prove "h" is invariant, but GR proves "h" is invariant in all
frames of reference. Indeed it looks to me that postulating
"h" to be invariant, (rather like "c" was in SR) one can
get a great deal of GR improvement and simplification.
Post by Jan VR
About Planck's constant: I know what it is and
what importance it has in Quantum Mechanics. But I do not really
'understand' it (as there are more things in QM which cannot be
understood...). Why do you ask ?
Well because you can prolly teach me about it, being
fresh out the can. My simple understanding is "h" is
a fundamental unit of action that is everywhere and
for all time the same in all references, that's almost
like a god scalar.
It is used deep inside sub-atomic particles and applies
well to the spectra from distant galaxies, irrespective
of the forces, velocities or accelerations applied to
the system, in fact so much, I bet you hardly give it
a second thought. Why, why don't you give it a 2nd
thought?
BTW Jan have you got a good handle on Special
Relativity, I'm guessing you do.
Regards
Ken
PS: Your pdf's worked fine for me.
PSS: Sal's a sharp fellow developing a web-site
always under construction, swoop in for gander.
Jan VR
2007-01-07 15:46:48 UTC
Permalink
Hi Ken,
Post by Ken S. Tucker
It's a no-brainer getting the Schwarzschild metric once
you know the answer, in fact it's rather easy to derive
from E =hv (Plancks photon energy equation), once you
prove "h" is invariant,
Can you show me how ?

Regards,
Jan
Dirk Van de moortel
2007-01-07 16:09:13 UTC
Permalink
Post by Jan VR
Hi Ken,
Post by Ken S. Tucker
It's a no-brainer getting the Schwarzschild metric once
you know the answer, in fact it's rather easy to derive
from E =hv (Plancks photon energy equation), once you
prove "h" is invariant,
Can you show me how ?
Daar ga je spijt van krijgen...
Hou je vast aan je bretellen ;-)

Dirk Vdm
Ken S. Tucker
2007-01-07 21:21:50 UTC
Permalink
Post by Jan VR
Hi Ken,
Post by Ken S. Tucker
It's a no-brainer getting the Schwarzschild metric once
you know the answer, in fact it's rather easy to derive
from E =hv (Plancks photon energy equation), once you
prove "h" is invariant,
Can you show me how ?
Well this is a start....

Begin with a massless lightbulb, and measure
the intensity of the bulb at various distances
using a 1 meter^2 receiver, basically measuring
light energy flux.
Well we know the photon intensity on the meter^2
is proportional to 1/r^2 in Newtonian physics.

In the early 1900's Planck established E=hf
(E=energy, h= constant, f=frequency).

Because of conservation of energy, light rays
(photons) going upward in a g-field, must loose
frequency, aka the Einstein shift. This gets
the metric g_00.

So now if we place a large mass M where the bulb
is, the intensity will reduce where the receiver
is, compared to when M=0 because of the *red shift*
of photons moving upward due to mass M>0.

To get the same photon intensity as when M=0,
the reciever will need to be set closer to the
M>0 bulb. That is why radial *length* shrinks
in a g-field, (g_11).

The Newtonian coordinates to retain the
conservation of energy are replaced by the KS,
coordinates accounting for E=hf in a g-field.

For ref see Weinberg's "Grav & Cosmo" pg. 84,
beginning with "Incidentally...", it's
uncredited, but I think reliable.

Jan, I think that will appeal to your "Nuclear Physics"
instincts.
Regards
Ken
Post by Jan VR
Regards,
Jan
General Relativity Theory (GRT) is like a legal document,
and because of General Covariance is written in the
language of tensors, and may well be the toughest
legal document ever written.
I agree with your sentiment that General Relativity
(apart from GRT) is quite understandable using High
School algebra, that's laudable, and in simple situations
works well enough.
Because gravity is such an overwhelming phenomena
it probably deserves your attention.
Ken
Eric Gisse
2007-01-07 00:51:09 UTC
Permalink
Post by sal
Post by Eric Gisse
Post by Jan VR
Hi,
http://home.scarlet.be/~tsd53243/
Any comments or feedback would be most welcome.
Your PDF links do not work.
They work for me, on 1/6/07.
Firefox behaves oddly with PDF links when Acrobat is not installed.
Forgot I hadn't installed it since I reinstalled XP.
Post by sal
Post by Eric Gisse
Post by Jan VR
Greetings,
Jan
--
Nospam becomes physicsinsights to fix the email
sal
2007-01-06 15:12:34 UTC
Permalink
Post by Jan VR
Hi,
http://home.scarlet.be/~tsd53243/
Any comments or feedback would be most welcome.
Thanks, Jan, the papers look interesting, and so far they seem pretty
"accessible". It'll be a while before I have anything intelligent to say
about them, tho (if I ever do!).
Post by Jan VR
Greetings,
Jan
--
Nospam becomes physicsinsights to fix the email
I can be also contacted through http://www.physicsinsights.org
Eric Gisse
2007-01-07 01:17:32 UTC
Permalink
Post by Jan VR
Hi,
http://home.scarlet.be/~tsd53243/
Any comments or feedback would be most welcome.
Cute - but no. It seems that you are well-meaning and not completely
ignorant, a pleasant change from the usual tidal wave of stupidity that
graces this newsgroup.

The surface integral stuff is uncontroversial and correct for Newtonian
gravity. No problems there.

The function psi you define in your first paper in accordance with the
Schwarzschild solution can not be accurately called a measure of
curvature. Curvature has a very specific meaning in general relativity,
and that is not it.

http://en.wikipedia.org/wiki/Riemann_curvature_tensor
http://en.wikipedia.org/wiki/Scalar_curvature

You are mixing and matching ideas from Newtonian gravitation and
General relativity with complete abandon.
Post by Jan VR
From (7) onwards, your paper flies off the deep end. Equation 7 is
wrong - the dot product's output is a real number and is most
certaintly not equal to the metric tensor.

Equation 9 gives the right answer but it has no justification. In
Riemannian geometry, the volume element is given by the square root of
the determinant of the metric times the usual volume chunk.

Equation 11 is interesting because you suddenly started noticing
indicies.

I really, really suggest you pick up a decent book on general
relativity. You honestly do need to pick one up rather than trying to
re-invent the wheel.

I believe you would find the concept of the weak field limit to be
quite interesting. Plus you would be able to see where the
Schwarzschild solution comes from rather than postulating it.
Post by Jan VR
Greetings,
Jan
s***@gmail.com
2007-01-07 01:36:42 UTC
Permalink
Post by Eric Gisse
Post by Jan VR
From (7) onwards, your paper flies off the deep end. Equation 7 is
wrong - the dot product's output is a real number and is most
certaintly not equal to the metric tensor.
You've misunderstood the notation. The notation assigns the (u,v)
component of the metric tensor to the measure of orthogonality between
the u'th and v'th basis vector (which are not orthogonal).
Jan VR
2007-01-07 16:07:15 UTC
Permalink
Hi Eric,

Thanks for your comments; it's pretty clear that you dislike the simple
model I was suggesting...
Post by Eric Gisse
Equation 11 is interesting because you suddenly started noticing
indicies.
I think there is nothing wrong with the vector notation that I used in
the text. If you're not familiar with it, check out the Arfken and
Weber book for instance (see the references).
Post by Eric Gisse
I really, really suggest you pick up a decent book on general
relativity. You honestly do need to pick one up rather than trying to
re-invent the wheel.
I have read and studied several books on the topic. I think I am well
aware of the GR principles. But feel free to confront me with the
errors you find in the text (based on arguments).
Post by Eric Gisse
I believe you would find the concept of the weak field limit to be
quite interesting. Plus you would be able to see where the
Schwarzschild solution comes from rather than postulating it.
If you read the complete text, it should be clear that I do not
postulate the Schwarzschild solution. The only postulates are the 4
assumptions, see the text.

By the way, I do not want to re-invent the wheel. I just want to show
that the gravitational field can be treated pretty much the same as the
electrical field. This would make things a lot easier in my opinion.

Regards,
Jan
t***@verizon.net
2007-01-07 17:17:38 UTC
Permalink
Post by Jan VR
Hi,
http://home.scarlet.be/~tsd53243/
Any comments or feedback would be most welcome.
You wrote:
"...what bothers me are the Einstein field equations. They are
mathematically rather cumbersome and are hard to interpret
physically."

Are you familiar with the work of Ashtekar? The traditional route to
characterizing the geometry of S is via a metric tensor. In 1986,
Ashtekar pioneered an approach in terms of connections (connection
dynamics), which, for a large set of problems, is mathematically
much more tractable and has led to many advances in recent years,
for example in the area of loop quantum gravity, etc.

It would probably be more productive of you to spend a bit more time
reading up on recent research in gravitation theory before venturing
out on your own. Textbooks still tend to follow the traditional
route, which is excellent from a heuristic standpoint, but is perhaps
not optimum from other standpoints...

Keep studying! And have fun! :-)

Tom
John C. Polasek
2007-01-07 19:08:44 UTC
Permalink
Post by Jan VR
Hi,
http://home.scarlet.be/~tsd53243/
Any comments or feedback would be most welcome.
Greetings,
Jan
Your stuff looks good till one realizes you think gij is a scalar
product as in Eq. 11. You think gij is a metric field, on page 2 if I
recall. This is all too slovenly.
The METRIC is gij xi xj making the Schwarzschildild metric as a
scalar product. gij is simply a tensor whose job it is to distort xi
and xj.
Other than that, since curved spacetime does not exist, it would be a
waste of effort to see if you made any other errors.

John Polasek
Jan VR
2007-01-08 20:24:32 UTC
Permalink
OK, I see I have been messing up the notations for the 'metric' and the
'metric tensor'. If this confused you, or even offended you: the latest
versions of the texts should be more accurate.

Regards,
Jan

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