baudrunner's space: Where are the gravitational waves..?
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Tuesday, January 22, 2008

Where are the gravitational waves..?

The Laser Interferometer Gravitational-Wave Observatory (LIGO) facility at Hanford is the largest single enterprise ever undertaken by the National Science Foundation. It was built at a cost of about $300 million and has operating costs of about $20 million per year. The facility is designed to detect gravitational waves, predicted by Albert Einstein to exist in his General Theory of Relativity in 1916. Essentially a precision laser in a specially constructed cavity, it is by far the most sensitive instrument ever designed, able to measure displacements as small as one thousandth the diameter of the proton. Such a displacement is predicted to occur when a gravitational wave passes through the laser cavity, and because the gravitational wave is predicted to alter space time it is actually expected to alter the dimension of the cavity, providing proof of its existence.

The GEO600 is another laser interferometric gravitational wave detector designed and constructed by a British-German Collaboration comprising the University of Glasgow, University of Cardiff and Albert-Einstein-Institut, and University of Hanover and Max-Planck-Institut für Quantenoptik. It is located in the town of Ruthe, near Hanover, Germany. The UK contribution to this project alone is about £31 million.

There are other gravitational wave detectors including the VIRGO Interferometric Antenna, a French-Italian collaboration under the auspices of the European Gravitational Observatory (EGO). All three of the above observatories finished a spectacular science run on the first of October of this year and analysis of their accumulated data does not show the detection of gravitational waves. An October 2007 report (19 pgs, .PDF) by VIRGO crew gives a good impression of their facility. Amazingly, the sensitivity of the observatory, which is located in Tuscany, is such that it can detect waves crashing on the sea shore during a violent storm. Its reach is about five times the distance between the Milky Way and the Andromeda galaxies.

While gravitational waves have not yet been directly detected, they have been indirectly inferred from the observation of a binary pulsar. The characteristics of the pulsars vary in time, as would be predicted by Einstein's General Theory of Relativity. The 1993 Nobel Prize for Physics was awarded to Joseph H. Taylor Jr and Russell A. Hulse for their work in noting the evidence for gravitational radiation, which can only be produced by gravitational waves.

One wonders just how sensitive a gravitational wave detector must be in order to prove the existence of gravitational waves. Since cosmic disturbances of the kind that generate these waves have been occurring for all time and continue to occur their presence should have been detected by those very sophisticated instruments by now. I wonder if it could be that such detection could not be possible since the laser beam occupies the same space-time as the special cavity wherein it is operating and any alterations occurring to the cavity because of space-time effects must of needs be occurring to the laser equipment as well.

According to relativity theory, the observation of an event is relative to an observer outside of the context of that event. This concurs with the observation of the binary pulsar, but one cannot expect to observe the relativistic effect of an event from within the same context as the event itself.

An argument might be made for the fact that established theory holds that the speed of light is constant in all frames of reference and this is no doubt the premise on which the gravitational wave detection observatories are based. Firstly, the speed of light is a function of the density of the medium through which it propagates, as demonstrated by the prism and by the refraction of light in water. Secondly, as we all know, nature abhors a vacuum, and not just the medium but also the equipment which generates the laser beam will be affected by any predicted changes in space-time, as will of course the virtual space through which the beam propagates. Furthermore, and this is pure speculation, the work done by Dimitri Nanopoulos, Distinguished Professor of Physics at Texas A&M University in 2001 suggests temptingly that when a gravitational wave passes through the beam the effect on frequency and therefore velocity is such that no detection of the gravitational wave can be achieved, since those effects would complement the effect on the cavity.

I certainly don't deny the existence of gravitational waves. After all, space is curved and has a mutable density and those properties can safely be presumed to be dynamic. However, I don't think that the capability exists for the detection of gravitational waves in the laboratory using the current method.

addendum: proposal for an alternate experiment for the detection of a gravitational wave

It occurs to me that an experiment whereby a photon entanglement occurs over a distance great enough to represent a measurable time differential of the passing wave front might provide the evidence we seek for the existence of a gravitational wave. Detection of the space-time anomaly would occur before the wave passes by the earth based photon(s).

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