One evening in March 1931, a lone car made its way along an unlighted road in “the wilds of Santa Ana,” as one passenger later described it, toward the vast open space of the Irvine Ranch.
When it arrived at the Ranch, the car pulled up to an odd two-story wooden building from which a 3-foot-wide metal pipe extended as far as the eye could see into the darkness.
The car door opened and Albert Einstein stepped out into the dim lamplight from the scientific station, to be greeted by another giant of 20th century physics, Dr. Albert Michelson. (Michelson Drive in Irvine is named after Dr. Albert Michelson.)
Michelson came to the Irvine Ranch in 1929 after doing a series of experiments at the Mt. Wilson Observatory to measure the speed of light. Not satisfied with those results, Michelson proposed — and was awarded funding for — a mile-long vacuum tube with mirrors at each end to bounce a light beam back and forth many times to get a more accurate measurement of its speed.
The tube ran alongside a ditch that is now a flood-control channel a half-block east of Armstrong Avenue, running south from near what is now Alton Parkway. Composed of 60-foot sections that had to be joined with airtight seals, the “light tube” took more than a year-and-a-half to construct. Michelson was just about ready to begin experiments when Einstein, who was spending a semester as a visiting professor at the California Institute of Technology, paid his visit.
The careers of Michelson and Einstein had by 1931 been intertwined for more that four decades, beginning in 1887 with the famous Michelson-Morley experiment, often called the most important failed experiment in the history of science. The experiment was to detect the effects of the so-called “ether,” the substance through which light waves were thought to move like sound waves through air. In failing to find these effects, the experiment actually showed that ether did not exist, forcing a total rethinking of the physics of light and cosmology that led to Einstein’s breakthrough theory of special relativity in 1905 and the iconic E=mc2.
Both celebrated scientists had won the Nobel Prize for Physics, Michelson in 1907 and Einstein in 1922.
In a letter soon after the meeting, Walter Adams, the director of the Mt. Wilson Observatory, who accompanied Einstein to Irvine, wrote to a friend, “I know you would have enjoyed seeing Einstein and Michelson sitting side by side on an old army cot discussing the details of the apparatus.”
“It was a wonderful moment,” says recently retired UCI physics professor and Associate Dean Dr. Roger McWilliams. “Represented here were the two methods, theory and experiment, that give us our scientific understanding.”
The Irvine meeting would be the last for the two great physicists. Six weeks later, Michelson died at age 78.
Michelson’s team continued the light tube experiment and obtained a value of 299,774 kilometers per second for the speed of light in a vacuum. Modern measurements put the speed of light at 299,792 km/sec.
This year, thanks to the efforts of a group of UCI and Irvine community members, a historical marker commemorating the Michelson light tube experiment will be placed near where Michelson and Einstein once sat on an old army cot and talked shop.
A detailed account of Michelson’s light experiments in Southern California by local historian Thomas Mahood, with many photos, can be found here.
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