Wednesday, June 04, 2008

Astronomical Unit Changing?

The Lunar Laser Ranging Experiment from 1969 provided one more indicator that the speed of light is slowing to this day.

Tuesday's New York Times reported the dismal state of "dark energy" research. Even the revered Ed Witten is at a loss to figure it out. There is no compelling theory for DE, researchers can't even agree on a mission concept, and the amount NASA has budgeted for JDEM is barely half what would be needed. All it would measure is an "equation of state." With all this flailing about in the dark, the reputation of science is slowly eroding. "We are placing a large bet," admitted the Director of the Space Telescope Science Institute, "using our credibility as collateral that we as a community know what we are doing."

GM = tc^3. As age of Universe t increases. light slows down. This would affect the redshifts of distant supernovae, making the Universe appear to accelerate. This produces a precise fit to supernova observations. A child could figure it out, yet until recently talk of changing c would get reactions ranging from willful ignorance to sexist attacks. Publishing papers on a changing c is still quite difficult. Childishness can not stop a growing body of evidence.

There is yet another indicator that c is slowing. The astronomical unit is the distance from Earth to Sun. By using Earth's orbit as a baseline, astronomers use the AU in calculating the parallax distance to nearby stars. Accurate measurements of the AU affect all our measurements of distant objects, as does the speed of light. Recent experiments seem to indicate that the AU itself is growing!

By analyzing radio echoes from the planets, G.A. Krasinsky and V.A. Blumberg measured change in the AU at about 7 cm/yr (Note 1). Independently E.M. standish estimates the change as about 5 cm/yr (Note 2). These estimates are made from many measurements, so they are likely to vary. Unlike the Moon's drift from Earth, growth in the AU can not be explained by tidal effects.

If the speed of light us slowing, the time for radio waves to return would increase, making the AU appear to grow. Suppose we measured the AU directly by bouncing light rays off the Sun. We can't do that for obvious reasons, but we can determine the approximate size of the effect. We have:

GM = tc^3 where t is age of the Universe, about 14 Gyr

c(t) = (GM)^{1/3} t^{-1/3}

cdot/c = -1/3t = -1/(42 Gyr)

Multiplied by an AU of 149 million kilometers, that distance will appear to increase by:

-(149E9 meters)/(42 Gyr) = 3.5 m/yr

The AU should appear to grow by 3.5 m/yr. If the measured recession appears smaller, Earth could conceivably be moving closer to the Sun! That would be very logical, as many theories of the solar system state that planets should drift inward. Earth could be headed toward a very hot fate, which we are kept from realising by scientists' insistence that c is constant.

The hypothesis of a repulsive "dark energy" has led nowhere. Betting on it has eroded the reputation of science. Data from Type Ia supernovae, the Lunar Laser Ranging Experiment and "Faint Young Sun" also indicate that c has slowed at the rate GM = tc^3 predicts. Eventually the weight of evidence will be too big to ignore. In the meantime, making new discoveries is a daily joy.

Women of Space are saluted in the new Carnival of Space!


[1] G.A. Krasinsky and V.A. Brumberg, "Secular increase of astronomical unit from analysis of the major planets motions, and its interpretation," Celest. Mech. & Dyn. Astron. 90:267, 2004.

[2] E.M. Standish, "The Astronomical Unit Now," in Transits of Venus: New Views of the Solar System and Galaxy, Proceedings IAU Colloquium No. 196, page 163. Cambridge University Press, Cambridge, 2005.

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Blogger Stephen said...

If the speed of light is changing by that much, it wouldn't just be the pioneer anomaly, and it would just be an anomaly for probes as they pass the Earth. It wouldn't just be trivial to see, it'd be impossible to ignore in space navigation.

Call me skeptical.

Dark matter was discovered something over seventy years ago. Dark energy was discovered about ten. Since the discovery was difficult, i don't think we're out of the confirmation phase. In addition to SN studies, we might try GRB studies to push the envelope back a bit. I'd be content if we didn't spend huge bucks on a space mission for at least another decade. Not that i don't want to know what it is. I'd just rather have a follow on HST for visible light astronomy for when the HST takes a dive into the Pacific. I bet we could get a capable scope up for half a billion.

1:47 AM  
Blogger L. Riofrio said...

Lots of people are skeptical about "dark energy." Newton's laws are sufficient to guide Spacecraft in the solar system. If the AU is only increasing by 3.6 cm/yr, it would not impede navigation.

7:51 PM  
Blogger Spinoza said...

Of course the AU is growing!! It's a well known effect and it has nothing to do with c changing. It is due to the fact that the mass of sun is decreasing, since it irradiates energy, and therefore mass.

6:01 AM  
Blogger William said...

Edward Arthur Milne derived this equation GM=tc^3 in 1934. Paul Dirac also derived a similar equation. The question remains is c varying or is G or M any combination.

9:40 AM  
Anonymous Anonymous said...

"William" is truly thinkning...What he is really trying to say is, "What IS constant? bc the only 'contant' in life and our Universe is our 'Uncertainty.'"

9:50 AM  
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