Monday, July 20, 2009

Apollo 40th

Monday was climax of the Newspace Conference here at NASA Ames. Representatives of the Space industry; along with the 10,000 who attended the Moonfest; remember the significance of this date. The Apollo program was an enormous bounty for science. A whole generation of scientists were inspired by seeing people reach for the Moon. American schools began emphaising science and math to stay ahead of the world. The most productive years in particle physics, leading to discovery of the J-psi particle, coincided with the height of Apollo. The program may have left us the biggest gift of all.

The Lunar Laser Ranging Experiment left behind by Armstrong and Aldrin has been worth the price of the program. LLRE has allowed precision mesasurements of the Moon's distance, measurements of the gravitational constant, and one more check of Relativity, 400 years ago Galileo suggested measuring the speed of light using lanterns on distant hilltops. Following Galileo's idea, LLRE may have provided some important data.

LLRE reports the Moon receding at 3.82 +/- 0.07 cm/yr, anoimolously high. This implies that the age of the lunar orbit is only 1.55 Gyr. Apollo Moon rocks are over 4.5 Gyr old, proving to science that the Moon and planets are at least that old. Multiple clues from geology and paleontology (which will be described later) indicate that the Moon has receded at only about 2.8 cm/yr. How can LLRE be so far off? The answer may be as obvious as the Moon in the sky.

If the speed of light is slowing according to GM=tc^3, time for light signals to return would increase each year, making the Moon appear to recede faster as seen by LLRE. If the Moon's distance were fixed, LLRE would still report it receding at 0.935 cm/yr. change in c precisely accounts for the discrepancy. Apollo may have proven that the speed of light slows as we speak.

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Anonymous Ed Davies said...

Intriguing. You've posted on this before but the presentation of the numbers was a bit confusing and I didn't really follow. As you've put it here it's a lot clearer.

I'm looking forward to your description of the geological evidence for the rate of retreat.

Has anybody been giving alternative explanations for the discrepancy?

7:10 AM  
Anonymous Anonymous said...

Louise, you've discussed this many times in the past but what I haven't seen addressed is the issue that your estimate of the recession rate 2.9 ± 0.6 cm/yr is not significantly different from the LLRE rate 3.82 cm/yr.

The value 3.82 is well within two standard deviations of 2.9 - there is a difference of only (3.82 - 2.9)/0.6 = 1.53 standard deviations. This is just not a statistically significant difference.

As I'm sure you know, effects even in the lab are not considered significant unless they are seen at > 2-sigma, and for astrophysics anything less than 5-sigma is usually considered suspect.

5:56 PM  
Blogger L. Riofrio said...

Hello all. Much more precise measures are available, as shall soon be seen.

6:45 PM  
Blogger qraal said...

The proximity of the Moon isn't a fixed function, but depends strongly on resonances set up by tides in the oceans of Earth. Currently we're dissipating a lot more tidal energy than would naively be expected, but all the geophysical evidence points to lower tidal dissipation rates in the deep past, when the energy loss quality factor (Q) was higher. Currently it's about 12, but was more like 100 in the deep past - the rate of energy dissipation is inversely proportional to Q.

So there's no "young Moon" mystery really. There might be hints of the processes you're suggesting in the tidal records, but you'll need to extract signal from the noise yourself - thousands of daily tidal sequences are preserved as rhythmites from several different epochs, like the Archean (c.3.2 Gya), Proterozoic (c.0.9 Gya) and Phanerozoic (several.)

1:24 AM  
Blogger Doug said...

I have been looking at your ideas with interest but uncertainty, until you now come up with something about the recession of the moon, which is a pet interest of mine.
Although the contribution of the VSL doesn't alone allow the existence of the moon for over 4 billion years, it resolves the past billion years, which is the period for which we have fairly clear data.
I am now intrigued!

5:51 AM  
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8:46 PM  

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