Date: Sat, 29 May 2004 01:14:20 +0300
From: Dimi Chakalov <email@example.com>
To: Clifford Will <firstname.lastname@example.org>
On Fri, 28 May 2004 14:28:29 -0500 (CDT), "Clifford M.
Sorry, I had the impression that you like alternative theories of gravity.
I suppose this is also your reply to my request for a copy from your "Does Spacetime do the Twist? The launch and implications of Gravity Probe-B", which I needed to be prepared for your talk "Alternative Theories of Gravity" at GR17.
See you in Dublin.
On Thu, 13 May 2004 03:10:19 +0300, Dimi Chakalov wrote:
Note 1: I'm used to such harsh replies from theoretical physicists, my first request for opinion & preprints was in August 1981. I wrote to Prof. David Abramovich Kirzhnitz (USSR), requesting his opinion on my speculations on the quantum vacuum, and in October 1981 I got a letter in which he said nothing, but from the bottom of his communist heart.
That was in the dark communist era. Now we have email, and it's much easier to say nothing, as did Prof. Clifford Will (probably also from the bottom of his heart).
Clifford Will has written a nice book "Was Einstein Right?" (hence the acronym WER?), but the reason for my interest in his research is the following excerpt from his web site, Has the Speed of Gravity Been Measured?:
"How can we really measure the speed of propagation of gravity? (...) The real way to measure the speed of gravity is to detect and study gravitational waves."
I have a bit different opinion on Sergei Kopeikin's project, which you can read here.
Note 2: Clifford Will has published a very intriguing article in Sec. Special Focus in October 1999 issue of Physics Today [Ref. 1].
I'm afraid two important issues are 'swept under the rug'. I intend to ask Clifford Will two questions, after he delivers his talk "Alternative Theories of Gravity" at GR17.
Firstly, the comparison of detecting GR waves to the detection of neutrinos is by no means justified. Unlike neutrinos, the hypothetical graviton may not exist (cf. Mário Everaldo de Souza, Gravity cannot be quantized, gr-qc/0208085, and Angelo Loinger, "Quantum gravity": an oxymoron, physics/0308042). What Clifford Will failed to explain is the implications of non-existence of graviton to the theory of detecting GR waves. Hence my first question:
Q1: If the graviton cannot exist in principle, what would you need to fix in your theory of detecting GR waves?
Secondly, the very idea of detecting the polarization of gravitational waves [Ref. 1, Fig. 3] could be wrong, since there is no solution to the puzzle of 3-D space in GR, nor any answer to the question of how can these putative waves propagate within themselves, and with respect to themselves (cf. Kip Thorne's lecture at GR17). Here comes my second question:
Q2: Albert Einstein has said that the representation of matter by a tensor was only a fill-in to make it possible to do something temporarily, a wooden nose in a snowman [Ref. 2]. Was Einstein right (WER?)?
Should this question sound strange, may I suggest the reader to consult Hermann Weyl [Ref. 3]. The crux of the matter is in the equation of continuity (Ibid., pp. 268-269, Eq. 55): we assume that "outside" the world canal, the stream-density si vanishes, "if not entirely, at least to such a degree that the following argument retains its validity".
However, the stream-density does not vanish entirely, and we cannot set it to strictly zero: Hermann Weyl was talking about an artificial "isolated system" (Ibid., p. 268). So, if we place the global mode of spacetime "outside" the world canal and "between" any point at which si is tending asymptotically toward zero, the whole case changes drastically, as anticipated by Einstein [Ref. 2]. And please don't forget the enigmatic [lambda]. More from Lawrence Krauss [Ref. 4].
I don't expect Clifford Will to reply to these questions, and I don't expect any of his colleagues to pay attention to these issues either. Then by 2011 they will find out that the so-called gravitational waves cannot be detected (see LISA and LIGO), and we will witness a drastic case of total ignorance and lack of understanding the basic problems of Einstein's GR.
Then Clifford Will will stand out and say, "People sometimes make errors", just as Edward Weiler did on September 30, 1999, after the crash of Mars Polar Lander spacecraft.
It happens. Just
don't tell me you
knew nothing about it, Clifford.
[Ref. 1] Clifford
M. Will, Gravitational Radiation and the Validity of General Relativity.
PHYSICS TODAY 52, 38 (October 1999). Based on a talk given at the
April 1998 meeting of the American Institute of Physics,
"GRAVITATIONAL-WAVE TESTS OF GRAVITATION THEORY
"First, detection of the waves would
in and of itself be a striking confirmation of general relativity, despite
the fact that their existence is strongly supported by the binary pulsar.
Here the situation is reminiscent of neutrinos: the direct detection of
neutrinos by Frederick Reines and Clyde Cowan in 1956 was a impressive
discovery (worthy of the 1995 Nobel Prize) despite the pre-existing confidence
in their reality from beta decay.
of gravitational waves. A laser-interferometric or resonant bar gravitational-wave
detector measures local relative displacements (of mirrors or of mechanical
elements), which can be related to a symmetric 3x3 strain tensor. This
tensor can in turn be related directly to components of the Riemann curvature
tensor of spacetime generated by the wave. The six independent components
of the strain tensor can be expressed in terms of polarizations (modes
with specific transformation properties under rotations and boosts). Three
are transverse to the direction of propagation, with two representing quadrupolar
deformations and one representing a monopole "breathing" deformation. The
other three are longitudinal, with one an axially symmetric stretching
mode in the propagation direction, and the remaining two quadrupolar (see
Figure 3). General relativity predicts only the first two transverse quadrupolar
modes, independently of the source; this goes hand in hand with the notion
that, at a quantum level, gravitational waves are associated with a spin-two
particle, the "graviton"."
"FIG. 3. Six polarization modes for
gravitational waves permitted in any metric theory of gravity. Shown is
the displacement that each mode induces on a ring of test particles at
0o and 180o phase. The wave propagates in the +z
direction. There is no displacement out of the plane of the picture. In
the transverse modes, the wave propagates out of the plane; in the longitudinal
modes, the wave propagates in the plane. In general relativity, only the
transverse quadrupolar modes are present; in scalar-tensor gravity, the
transverse breathing mode may also be present."
From Albert Einstein's Last Lecture,
Relativity Seminar, Room 307, Palmer Physical Laboratory, Princeton University,
April 14, 1954, according to notes taken by J. A. Wheeler. In: P. C. Eichelburg
and R.U. Sexl (Eds.), Albert Einstein (Friedrich Vieweg & Sohn, Braunschweig,
1979), p. 201.
"And yet, physically, it seems devoid
of sense to introduce the tk as energy-components of the
gravitational field, for these quantities neither form a tensor nor
are they symmetrical. In actual fact, if we choose an appropriate co-ordinate
system, we may take all the tk at
one point vanish;
it is only necessary to choose a geodesic co-ordinate system."
pp. 54-55: "In the general theory of relativity, the source of gravitational forces (whether attractive or repulsive) is energy. Matter is simply one form of energy. But Einstein's cosmological term is distinct. The energy associated with it does not depend on position or time -- hence the name "cosmological constant". The force caused by the constant operates even in the complete absence of matter and radiation. Therefore, the source must be a curious energy that resides in empty space."