Monday, May 31, 2010

Pot Thief Tour 2010 - Day 17

Today’s signing was at COAS Bookstore in Las Cruces, home of New Mexico State University. Since I served as president of NMSU back in the nineties, members of the faculty and staff from the State’s Land-Grant University came by to say hello. Kurt Anderson is head of the Sunspot Observatory just outside of Cloudcroft. Sunspot is the leading solar observatory in the world and part of the reason why NMSU has one of the best astronomy departments on the planet.

Kurt told me about an experiment they are conducting at Sunspot to verify Einstein’s theory of equivalence, a corollary of E=MC2. The theory of equivalence posits that the gravitational pull of an object is a function of its heat as well as its mass. This has never been proved. If Einstein’s theory is true, then the Sun’s gravitation force should be in part a function of its heat. The folks at Sunspot are trying to prove this by measuring the Sun’s effect on our moon. They have been measuring periodically the moon’s distance from the earth by bouncing a laser beam off objects left on the moon by astronauts. These measurements need to be extremely precise because the calculation of the effect of the heat part of the Sun’s pull on the moon shows that it would distort its orbit by less than an inch!

The experimenters also need to know how far they are from the center of the earth in order for the measurements to be useful. You may think that would be simple – just measure their altitude. But altitude is not a constant. Temperature, air masses, and even plate tectonics push the Sunspot Observatory several inches away from or closer to the center of the earth. Thus, they have to take simultaneous measurements of the altitude of the observatory and its distance from the moon.

They have been taking these measurements for a couple of years and will continue for several more in order to have enough data to support a finding, but the evidence so far seems to support Einstein’s hypothesis. Why are we not surprised by this? Maybe that’s why the next book in my series is The Pot Thief Who Studied Einstein.

Kurt bought two copies of The Pot Thief Who Studied Ptolemy. I signed one copy for him then asked how he wanted me to sign the second copy. “Sign it to Patsy Tombaugh,” he said.

I had no idea Patsy was still alive. Her husband, Clyde Tombaugh, was a faculty member at NMSU. He was also the discoverer of the planet Pluto and a number of other important things such as the fact that the red spot on Jupiter is a storm. I dedicated The Thief Who Studied Ptolemy to Clyde who died in 1997 at the age of 97. I was delighted to learn that Patsy is still alive and humbled and honored to sign a book for her.

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