|Subject: Advanced LIGO, Superconducting
Super Collider, etc.
Date: Tue, 15 Mar 2005 17:26:48 +0200
From: Dimi Chakalov <email@example.com>
To: Deepto Chakrabarty <firstname.lastname@example.org>
CC: Bruce Allen <email@example.com>,
M Mitchell Waldrop <firstname.lastname@example.org>,
David Nice <email@example.com>,
Barry C Barish <firstname.lastname@example.org>,
Angelo Loinger <Angelo.Loinger@mi.infn.it>,
email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com
RE: Maggie McKee, Fast-spinning star could test gravitational
waves, New Scientist, 22 February 2005,
"There is controversy over the gravitational wave idea
[as a brake on
Dear Professor Chakrabarty,
I'm afraid LIGO was born dead, in much the same way as the Superconducting Super Collider. The so-called ripples of spacetime metric or gravitational waves cannot be detected *in principle*,
The sole difference between the two projects is that the
Advanced LIGO, with "improved sensitivity", is relatively cheaper than
All this boils down to satisfying the obsessions of people
"Robbie Vogt, a physicist at Caltech and LIGO's founding-father, was replaced by Barry Barish, a high-energy physicist with experience in managing large parts of the now-defunct Superconducting Super Collider."
With taxpayers' money, however.
I think this is pathetic.
Moreover, people like Bruce Allen have organized the so-called
Maggie McKee, Thousands join hunt for gravitational waves,
Neither Bruce Allen nor Barry Barish or ANY of the LIGO scientists have mentioned the research by Prof. Angelo Loinger, who have proved that the hypothetical gravitational waves cannot exist *in principle*,
The proof has been delivered first by Hermann Weyl in 1944, but nobody from LIGO is interested. See the link above for references.
Let me stress that everything said in this email about
GWs can be
I will be happy if you raise your voice and write to NSF
Last but not least, LIGO people should never involve Albert Einstein. He was an honest person, and would have never said half of the truth to the lay audience.
Subject: Advanced LIGO
In MOG-25, gr-qc/0503086 v1, p. 8, you wrote:
"A closing note on this choice is that, since the internal thermal noise is considered to be quite low for fused silica, any extra improvements in coating thermal noise will lead to similar improvements in the Advanced LIGO sensitivity. A nice challenge!"
I'm afraid thermal noise coating may not help you detect GWs,
There is a really nice challenge from H. Weyl and A. Loinger at
Should you or your colleagues have questions, please don't hesitate.
Note 1: Let me write a few brief notes on GWs, which are intended to graduate students studying GR, such as those taught by Prof. Marc Kamionkowski. If you are familiar with the subject, you may skip these problems, they are well-known since the inception of Einstein's GR.
In addition to the papers by Hermann Weyl and Angelo Loinger, note that the physicists above do not consider the so-called gravitational waves (GWs) as something resembling the empty waves (de Broglie waves propagating in Minkowski spacetime; cf. F. Selleri, On the direct observability of quantum waves, Found. Phys., 12 (1982) 1087-1112). On the contrary, they deeply believe that GWs are capable of interacting with physical bodies. Specifically, they believe the perturbation of spacetime metric might be sinusoidal in nature, and calculate the much-desired (and still unobserved) effect as due to the quadrupole radiation; more from Clifford Will here.
Here's a brief list of unsolved mysteries.
1. How could GWs propagate within themselves, and with respect to themselves? (Kip Thorne keeps quiet, since March 2003.) Hint: pin down the amplitude of GWs, bit don't "collapse" it à la von Neumann and Born, because you will need it to display the sinusoidal propagation of GWs within themselves and with respect to themselves.
2. What will be the duration of the interaction of GWs with LIGO? If it's "instantaneous", like the "collapse" in QM, we're talking parapsychology.
3. If it isn't instantaneous, please write down the conservation equations for the energy of GWs for this finite time interval, and explain the conversion of the "energy" of GWs into something that you know from classical physics and/or QFT. Hint: don't miss the graviton.
4. After completing all the tasks above, you will be able to say something on the nature of dark energy, since it is the only entity that can (supposedly) alter the spacetime metric. Only its physical nature is very, I mean, very dark.
Of course, there
are compelling evidence that GWs exist, as the readers of Scientific
American know very well. I'm not saying that GWs do not exist.
On the contrary, both GWs and quantum waves are bona fine empty
waves "traveling" in the global mode
of spacetime. These empty waves can contact the local mode of spacetime
only through the apex of Minkowski cone, however.
Thus, they are unobservable with LIGO, LISA, tarot cards, crystal balls,
Big Bang Observer, regrettably. You need
a brain to detect the "unzipped"
virtual reality of gravity. It's an
Note 2: Let me quote from AEI web site: "Additionally, the GW group plays an active role in LISA, a planned space-based gravitational wave detector (currently scheduled to fly in 2013) that will be built jointly by ESA and NASA. Karsten Danzmann (Director of the AEI Division of Laser Interferometry and Gravitational Wave Astronomy) is co-Chair of the LISA International Science Team, and both Schutz and Cutler are also on this team."
On Thursday, March 31, 2005, Bernard F. Schutz delivered an one-hour talk "The inevitability of gravitational waves" (15:45-16:45) at "SPACETIME IN ACTION: 100 YEARS OF RELATIVITY" (Pavia, March 29 - April 2 2005).
On the next day, A. Ashtekar gave his Public Lecture "Space and Time: From Antiquity to Einstein and Beyond". The last slide of Ashtekar's talk reads the following: "We already have fascinating glimpses through Quantum Geometry. Breakdown of the continuum is a radical paradigm shift because all physical theories presupposed it! In particular, it reshapes the question we can meaningfully ask about The Beginning and The End!"
Abby Ashtekar must have been really excited, since he seldom uses exclamation marks. Thirteen years ago, in July 1992, he explained the crux of the problem (gr-qc/9302024): "The probabilities for an exhaustive set of mutually exclusive alternatives should add up to one. In quantum mechanics, this is generally ensured by using an instant of time to specify such alternatives. What is one to do when there is no time and no instants? These are fascinating issues."
Needless to say, Ashtekar's "fascinating glimpses through Quantum Geometry", launched under the stipulation that the topology of time should be either cyclic or linear (slide 39, "Is Time Cyclic or Linear?"), didn't solve the problem above, but produced a number of exclamation marks and a peculiar statement (slide 42): "Quantum theory of Geometry developed primarily at the Center for Gravitational Physics and Geometry at PSU. Now used by research groups world-wide." Coincidently or not, his Public Lecture was reserved for April 1st.
Let's go back to Bernard F. Schutz' talk "The inevitability of gravitational waves". I sent him two very polite requests, by email, for a copy from the paper (if any) of his talk, but he didn't reply. Judging from Bernard Schutz' slides 5, 6, 10, and 18, his talk hasn't been essentially different from his article on gravitational radiation published five years ago [Ref. 1], hence I will comment on the latter.
In addition to the tasks mentioned
in order to detect these mythical gravitational waves, we need to sort
out a number of "fascinating issues". All of them
of energy in GR: "Energy is localized only in
regions, not at points" [Ref. 1]. It
is real energy, as Bernard Schutz says, but he failed to explain the
puzzle known as "non-locality" of gravitational energy. More from Hermann
Weyl and Laszlo Szabados.
T2. The shift from
dipole to quadropole approximation is highly deceptive: "As in electromagnetism
(Sic! - D.C.), the amplitude of the radiation is proportional to the second
time-derivative of Qjk" [Ref. 1]. However,
unlike electromagnetism, you need to single out the "projection" of the
axis [Ref. 1] on your region
(T1) affected by those mythical tidal forces. This
isn't some "xy-plane", as stated by Bernard Schutz. This is 3-D space.
How do you measure the duration of the metric perturbation of 3-D
space? With respect to what?
Truly fascinating tasks, à la Ashtekar.
T3. Define the "region"
(T1) in which your wristwatch can read this "second
time-derivative of Qjk" (T2), and prove that you are not
trying to "measure" the dark energy
but the "real energy" of GWs. Alternatively, prove that you are indeed
trying to measure the “dark side of the Universe”,
as stated by Bernard Schutz in his talk "The inevitability of gravitational
"96% of the Universe is incapable of emitting light or other electromagnetic
radiation, so GWs are our only window into what Kip
Thorne calls the “dark side of the Universe”."
If you're still alive and well, and do not encounter any catastrophic events by measuring the "wobbling" dark energy, shave and pack your luggage, since you'll be very soon invited in Stockholm to collect your Nobel Prize.
Again, I'm not saying that gravitational
waves do not exist. It's not that simple. Please read above.
[Ref. 1] Bernard F. Schutz, Gravitational Radiation, AEI-2000-020, gr-qc/0003069 v1. Accepted by Encycopedia of Astronomy and Astrophysics, 2000.
"In general relativity, Einstein used the principle of equivalence as the basis for a geometrical description of gravity. In the four-dimensional world of space-time, the trajectory of a particle falling freely in a gravitational field is a certain fixed curve. Its direction at any point depends on the velocity of the particle. The equivalence principle implies that there is a preferred set of curves in space-time: at any point, pick any direction, and there is a unique curve in that direction that will be the trajectory of any particle starting with that velocity. These trajectories are thus properties of space-time itself.
"Moreover, if there were no gravitational
field, the trajectories would be simple straight lines. Even in a gravitational
field, a small freely falling particle does not "feel" any acceleration:
its internal state is the same as if there were no gravity. Therefore Einstein
postulated that a gravitational field made space-time curved, and that
the preferred trajectories were locally straight lines that simply changed
direction as they moved through
"For gravitational waves, one could
make a very simple detector just by monitoring the distance between two
nearby freely falling particles. If they are genuinely free, then any changes
in their separations would indicate the passage of a gravitational wave.
Because this measures a tidal effect, the bigger the separation of the
particles, the bigger will be the change in their separation, at least
for particles that are separated by less than a gravitational wavelength.
Most modern gravitational wave detectors are designed to be as
big as cost and practicality allows.
"The question of energy in gravitational waves is still a delicate one. There is no question that waves carry energy (and momentum) away from their sources. Nevertheless, it is not possible in general relativity to localize the energy in the radiation to regions smaller than about a wavelength. Indeed the equivalence principle shows that "point" particles feel nothing, no matter how strong the wave. The wave only acts by stretching space-time, producing a tidal distortion in the separations between particles (see the discussion of polarization below).
"Energy flux carried by waves
"The energy in the waves can also be estimated from these equations and general physical principles. Quite generally, in classical field theories, the energy flux of a propagating sinusoidal plane wave is proportional to the square of the time-derivative of the fundamental field. In electromagnetism, the Poynting flux is proportional to the square of the time-derivative of the vector potential.
"In general relativity, the flux
is therefore proportional to the square of the time-derivative of h(t).
The proportionality constant must be built only out of c, G, and pure numbers.
"The calculation and equations in this section have been framed within a modified Newtonian model of gravity with a propagation speed of c, and one would expect some differences from general relativity. The most important difference is in the direction in which the tidal forces act. In the simple model, wave accelerations act in the z-direction, which was the direction of propagation of the wave. This is called a longitudinal wave.
"In general relativity,
gravitational waves are transverse waves: if the wave propagates
in the z-direction
then the tidal forces act only in the xy-plane. We will discuss
later the exact form that their action in this
p. 6: "Quadrupole approximation
"Again in electromagnetism, the dipole moment is defined as the integral
where [p] is the charge density and x_i is a Cartesian coordinate. If this integral is time-dependent, then the amplitude of the electromagnetic waves will be proportional to its first time-derivative dd_i/dt, and the radiated energy will be proportional (as we remarked earlier) to the square of the time derivative of this amplitude, i.e. to [XXX].
"In the post-Newtonian approximation
to general relativity, the calculation goes remarkably similarly. The monopole
moment is now the total mass-energy, which is the dominant source of the
gravitational field for
"However, here general relativity departs from electromagnetism. The time-derivative of the dipole moment is, since the mass-energy is conserved, just the integral of the velocity v_i:
"But this is the total momentum in the system, and (to lowest order) this is constant. Therefore, there is no energy radiated due to dipole effects in general relativity.
"The gravitational field far from the source does contain a dipole piece if d_i is non-zero, but this is constant because it reflects the fact that the source has non-zero total momentum and is therefore moving through space.
"A gravitational wave in general relativity is represented by a matrix h_jk rather than a single scalar h, and its source (in the quadrupole approximation) is Q_jk.
"As in electromagnetism, the amplitude of the radiation is proportional to the second time-derivative of Q_jk, and it falls off inversely with the distance r from the source.
"A factor of G/c4 is needed in order to get a dimensionless amplitude h, and a factor of 2 to be consistent with the definition in Equation (8). The result for h_jk is:
"General relativity describes waves
with a matrix because gravity is geometry, and the effects of gravity are
represented by the stretching of space-time. This matrix contains that
distortion information. Here is the information about the transverse action
of the waves that the quasi-Newtonian model of the last section did not
p. 11: "Observations of the gravitational
waves emitted by a wobbling horizon or by a particle in orbit around a
black hole have the potential to test the uniqueness theorem and thereby
to verify the predictions of general relativity about the strongest possible
p. 13: "If gravitational
wave astronomy follows the example of other fields, like X-Ray Astronomy
and Radio Astronomy, then at some level of sensitivity it will begin to
discover sources that were completely unexpected. Many scientists think
the chance of this happening early is very good, since the processes that
produce gravitational waves are so different from those that produce the
electromagnetic radiation on which most present knowledge of the universe
is based, and since more than 90% of the matter
in the universe is dark and interacts with visible matter only through