|Subject: RE: Gravity and its
speed. The number of dimensions.
Date: Sun, 16 Feb 2003 12:37:59 -0600
I think it's too early yet to assume that gravity always moves at light speed, and one should wait awhile. As with so many other things, one has different experiments supporting different interpretations.
First, what exactly is velocity, and what is a velocity of c?
Well, velocity is simply a rotation of the moving object having that velocity, out of the laboratory 3-frame, with respect to its lab frame propagation direction. Since we normally model in only 4 dimensions, that rotation has to be toward the time axis. So one gets special relativity, time dilation, Lorentz-Fitzgerald contraction, etc. from the fact that velocity is rotation.
The velocity c just means that a full orthorotation has now occurred, and the "length along the line of motion" of the object has reduced to zero as seen by the lab observer. So it is seen as a sort of wavefront moving at speed c, which is reminiscent of a photon or a planar EM wave. The object in its own "frame" is perfectly happy to still be a normal 3-space object.
With a 4-model, we only get a single orthogonal rotation available, so speed c (a single orthogonal rotation) is all we can get. That is a model characteristic.
If we change the model and add more dimensions, that is not the limit anymore since multiple successive orthorotations are available away from the lab frame. So we can have c, c-squared, c-cubed, etc. and essentially anywhere in between.
And it does indeed take many more dimensions than just four, to successfully model particle physics.
In my present view, we are not going to be looking at "either-or" cases. To say that speed c is the fastest possible is, e.g., to ignore de Broglie waves, which always move faster than light speed. If we say that de Broglie waves are not real, we then do away with much of modern physics altogether. Also, longitudinal EM waves move at superluminal velocities easily, and in the common old garden variety electrodynamics the potential itself can move at infinite speeds in certain gauges, just appearing everywhere at once, wherever it will be.
Much of the heat and fury over such "disagreements" is really a disagreement between interpretations and also between different models. Certainly we measure entities that move at speed c! And we also can detect the interaction results of entities that seem to move faster than c.
In an orthorotational model, speed c is all you can get if you are limited to four dimensions. Since that seems to be our "most immediate" universe's aspect, we see and measure lots of speed c entities. However, we also detect the traces of more subtle superluminal entities as well.
So I don't think it's an "either c or not" simple case. We do not measure gravity itself anyway; but only effects from some interaction with it that we detect. This means that the conditions of the detection process are also directly involved.
Anyway, I personally think the jury is still out on this one, as far as any "ultimate" answer. There are some problems for which gravity at the speed of light seems to be perfectly appropriate. There are others where it seems not to be appropriate.
Since just about every major weapons lab on earth has now discovered longitudinal EM waves, I suspect that in the future, when some of the clandestine stuff is eventually made public, one is going to be very surprised to find that lightspeed is not a limitation, even of electrical signals. Superluminal signaling has indeed been demonstrated, but the scientific community isn't going to allow it to be developed, until the community is dragged kicking and squealing across that finish line. That's true with many other things these days.
Maybe it's best to consider it like the difference between Newton's mechanics and relativistic mechanics. They are different models, and each has its realm of applicability and phenomena which its describes. One doesn't need Einstein to build a house. But one jolly well needs him to calculate the energy delivered to the plate of certain tubes where the electrons approach light speed on their way from the cathode to the plate.