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Re: [Phys-L] gravitational waves



Thanks for food for thought, John.

1) Why do I believe that gravitational waves are longitudinal? Because, according to Newton's law of universal gravitation, forces with which two particles, M and m, attract each other are directed along the straight line connecting them. My model is based on this classical law.

2) Yes, I know two other things: (a) the same is true for two charged particles (they interact along the line connecting them) and (b) the vector E of an electromagnetic wave is perpendicular to the line of wave propagation. This does not prevent electromagnetic waves from being transverse.

3) But I do not know how to explain this perpendicularity; I accepted it this as a fact. The (b), in other words, is not a logical consequence of (a), as far as I know. In that context I can only say that the longitudinal nature of gravitational waves is an assumption.

4) Note that my simple classical model remains valid if I assume that gravitational waves are transvers. But what is the gravitational analog of the vector E or vector B? Perhaps someone will elaborate on this.

Ludwik

===================================

On Apr 10, 2016, at 3:51 PM, John Denker wrote:

On 04/10/2016 11:40 AM, Ludwik Kowalski wrote:

2) Why do I resist replacing the M by the Q? Because electromagnetic
waves are transverse while gravitational waves are longitudinal, at
least in my mind.

In reality, they're not longitudinal.

The disk model predicts that they are, but in reality they aren't.
Just because you can build the model doesn't mean it's faithful
to reality.

Why do I resist replacing the M by the Q?

As Feynman was fond of saying, the same equations have the
same solutions. The model that predicts that gravitational
waves are longitudinal also predicts that electromagnetic waves
are longitudinal. So we know the model is wrong.

Either that or you need to come up with a credible excuse why
reasoning based on the model applies to gravitation but doesn't
apply to electromagnetism. No such excuse has yet been offered.

Also note that such an excuse would make the analysis very much
more complicated, and would run afoul of Occam's razor.

A scientist is obliged to account for all of the evidence.
Resisting the M versus Q cross-check means closing your eyes
to some excellent evidence as to the reliability of the model.

This reminds me of the fundamentalists who believe in forgiveness
(as required by scripture) applied to themselves, and stoning (as
required by scripture) applied to everybody else.

The equations of electrostatics and magnetostatics are remarkably
similar to the equations of inviscid fluid dynamics. Maxwell
built a /model/ of electromagnetism based on vortices in the
ether. It was a lovely model, but it wasn't faithful to
reality, so he threw it out and started over.

This is the daily life of the scientist. You build a model,
find that it is not faithful to reality, throw it out and start
over, and so on, iteratively, until you find something that
works.

5) My model does not predict "the wrong dependence of GW intensity on x."

I insist that the disk model (a) does make a prediction and (b)
the prediction is very wrong. I have explained this in detail
previously.

If you didn't check the x-dependence that's no excuse; you
should have checked.

Wrong with respect to what? Do the experimental data exist?

There is plenty enough experimental evidence to show that the
disk model is wrong. If it were "close" to right this would
require some effort, but since it is so very very wrong the
decision is easy. Sufficient data has been around for more
than 40 years, and is reasonably well known, one might even
say famous:
http://www.nobelprize.org/nobel_prizes/physics/laureates/1993/press.html

Additional evidence has accumulated since then. The recent direct
observation of gravitational waves is yet more evidence about the
typical GW intensity, and is inconsistent with the disk model by
many orders of magnitude.
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.061102
http://physics.aps.org/articles/v9/17

Furthermore the disk model's x-dependence is inconsistent with
conservation of energy, and there is a treeeeemendous amount of
evidence for that.

Furthermore the disk model's t-dependence is inconsistent with
basic notions of relativistic causality. Do you really want to
claim you have repealed the laws of special relativity? Really?

anything that comes remotely close is better than nothing

That's grossly fallacious. It's a false dichotomy. The disk
model is definitely not the only thing on the menu. Numerous
specific constructive alternatives can be found in this thread
and elsewhere.
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