Dr. Daniel Gezari worked for 28 years at NASA's Goddard Space flight Center, and is currently an Astrophysicist Emeritus. He received the NASA Medal for Exceptional Scientific Achievement. His current interests include tests of Lorentz invariance and searching for evidence of a preferred reference frame for light. Earlier this year he released a paper that has caused a stir.Lunar Laser Ranging Test of the Invariance of c
According to Gezari's paper, the Lunar Laser Ranging Experiment (LLRE) measures the speed of light c as 8 m/sec less than its formerly accepted value. Perhaps c has slowed since the canonical measurement? Even more surprising, Gezari claims that c varies by as much as 200 m/sec depending on the observer's direction. This would undermine Lorentz Invariance, which says that c is the same regardless of direction.
Typically, the Gezari paper has drawn criticism. One arxiv abstract reads "We show that the conclusion of a recent experiment [arXiv:0912.3934] that claims to have discovered that 'the speed of light seems to depend on the motion of the observer' is wrong." If true, Gezari's results would undermine the basis of Special Relativity that is taught in schools. The schoolteachers may not be happy.
Shortly after Gezari was published, a similar paper appeared from Reginald Cahill at University of Flinders, Australia:Lunar Laser-Ranging Detection of Light-Speed Anisotropy and
Cahill also claims that LLRE shows a variation in c. He also claims a correlation with spacecraft flyby anomalies. These papers show the value of Apollo lunar missions to Physics.
Galileo was criticized for claiming that Earth circles the Sun, but he was also interested in light. At the time there was disagreement whether light travelled instantaneously or had a finite speed. Galileo suggested stationing lanterns on distant hilltops to time light's passage. Of course clocks of his time could not possibly measure time so accurately. Finally in the 1750's Ole Roemer used observations of Jupiter's moon to show that light had a limited speed. Despite Roemer's accurate predictions, it was 50 years before his conclusions were widely accepted.
Thanks to Apollo, we can measure light with laser lanterns and the distant hilltop of the Moon. LLRE has reported the Moon's semimajor axis increasing by 3.82 cm/yr, anomalously high. If the Moon were gaining angular momentum at this rate, it would have coincided with Earth about 1.5 billion years ago. Apollo lunar samples (which this scientist has had the honour to touch) show that the Moon is nearly old as the Solar System, over 4.5 billion years. Measurements using tidal sediments and eclipse records show that the Moon is receding at about 2.9 cm/yr. LLRE disagrees with independent measurements by 0ver 0.9 cm/yr, a huge anomaly.
If the speed of light is slowing according to GM=tc^3, the time for light to return will increase, making the Moon appear to recede faster as measured by LLRE. Predicted change is 0.935 cm/yr, precisely accounting for a 10 sigma anomaly. Since a little equation was first published, cracks have appeared in the "constant speed of light" canon.
Other voices at GSFC, who do not have a fraction of Dr. Gezari's experience, have been telling the press that they have found acceleration caused by "dark energy." The explanation for DE and the apparent acceleration of redshifts is something a child could understand. Since redshifts are related to the speed of light, it is not the Universe accelerating but the speed of light slowing down. A repulsive "dark energy" can not survive the light of discovery.
Labels: moon, speed of light