Speed of Light

C = 186,282.3960 miles per second, plus or minus 3.6 feet per second

C = 299,792.4562 kilometers per second, plus or minus 1.1 meters per second

LIGHT: Albert Michelson was known as finest experimental physicist alive.

If rebuilt on its old site today, the speed of light experiment would run through an industrial park, in what is now the city of Irvine.

At the heart of the experiment (pictured in the shack and graphic above), an arc light was bounced off a rapidly rotating set of mirrors, back and forth down a mile-long tube and home, to the mirrors, which by then would have moved slightly. If the speed of the mirror, the angle of the bounce and the length of the tube are known, it is possible to calculate the speed of light.



Above, Albert Einstein and Albert Michelson met at Mount Wilson in 1931, just before Michelson's death. From left to right are Milton Humason, Edwin Hubble, Charles St. John, Albert Michelson, Albert Einstein, W.W. Campbell, and Walter S. Adams.

In 1887, Michelson and Edward Morely used the interferometer to find out how light waves moved through the theoretical "ether" in the universe. According to the principals of classical physics, the movement of the earth through this mysterious substance affected the speeds of light rays moving through it. Michelson and Morely used the interferometer to bounce light waves out and back at right angles, expecting to see one of the beams lag behind.

Instead, the beams returned at exactly the same time. In years to come, these findings would be cited as one of the first proofs this mysterious ether did not exist, that the speed of light was a constant, and that classical physics was not enough to explain the physical universe.

While Michelson and Morely were testing the "ether drift," Einstein had begun to speak of clocks that moved backward, mass that was not constant and light made up of things called "photons." For scientists, these heresies were as profound as those of Copernicus, the first to suggest that the earth was an orbiting planet, and not the center of the universe.

The drama surrounding Michelson's experiments was heightened by this atmosphere of turmoil. Although his work helped trigger a revolution in the study of physics, Michelson never decided which side he was on, according to his biographers.

His daughter, Dorothy Michelson Livingston, wrote that Michelson never gave up his belief in "ether," even though he accepted Einstein's work.

In 1930, that belief may have helped bring Michelson to Santa Ana, for his last and most ambitious test.

Athelie Clark, the oldest living member of the family that once owned the gigantic Irvine Ranch, remembers a day in the late 1920s when Michelson came to lunch.

At the table in the opulent dining room of James Irvine's Victorian home sat Michelson, James Irvine Sr., James Irvine Jr. and the scientist Robert Millikan. Clark sat and listened, understanding little of what was being said.

"I remember being told that he was a very famous man who was looking for a site for an important experiment," said Clark, now 85.

"His hair was gray and unruly. He seemed extremely gracious to me."

"Gracious" was one of the nicer words used to describe Michelson's manner. Throughout his career, as honors piled up, he had earned a reputation as both brilliant and unstable. He was an accomplished tennis player. an excellent painter and violinist, and so good at billiards that opponents complained that his knowledge of physics gave him an unfair advantage.. His few close friends described him as extremely loyal, fond of practical jokes, and quite cool under pressure.

Yet Morely, Michelson's early partner, said he feared that Michelson had suffered a "softening of the brain" early in his career, after Michelson was hospitalized for exhaustion in the 1880s. Michelson's first wife tried to have the scientist committed. One of his maids sued unsuccessfully for assault.

Dorothy Michelson Livingston wrote that her father often worked for days without sleeping or eating, that he sat alone at meals so his thinking would not be disturbed, that in turns he could be arrogant, distant, imperious and rude. A messy divorce made front-page headlines for weeks. The physicist also suffered from recurring nightmares, including one in which he rode a motorcycle up an endless hill.

"Americans have this obsession with mad scientists, and Michelson
fit the image," said UCLA physicist Wuerker. "He was the most famous American scientist of his day. Anything he did was news."

Mad or not, he was definitely prodigious.

In 1907 when Michelson won the Nobel Prize for physics, his career was only getting started. He beat off several challenges to his findings and honed his earlier work. In 1920, he was the first to measure the diameter of a star, called Betelgeuse, an achievement hailed in The New . Y or k Times as "astounding."

In 1926, the most spectacular of Michelson's experiments split the night sky between Mount Wilson and Mount Baldy.

With mirrors, turbines, his interferometer and an arc light, he measured the speed of light to within two miles per second of its currently accepted speed.

Horace Babcock, the emeritus director of the Mount Wilson observatory, remembers visiting the experiment as a child, seeing the light shooting out of the cracks in the shack where Michelson was at work.

Michelson wasn't satisfied with the results of the Mt. Wilson experiment. For one thing, he worried that "shimmers" of air between the mountains might have fouled his results. He also didn't trust the work of the United States Geodetic Survey team, which had measured the distance between peaks.

He wanted to repeat the test in a vacuum to measure a more precise speed and, perhaps, show the presence of the "ether."

Clark says Michelson settled on the Orange County site for the experiment after lunch in the Irvine family home, when James Irvine Jr. took the physicist for a drive in the family Packard. Michelson liked the low, flat bean field on the north end of the ranch, near what is now the Marine helicopter base. The Irvines agreed to donate the use of the land.

The project took shape quickly. Michelson's assistants built a metal shack to hold the turbines, the arc light and other equipment from Mount Wilson and a network of tubing, metal pipes, wires, plugs and switches. From the shack, they built a mile-long tube of 3-foot-diameter, corrugated steel pipes sealed airtight by layers of steel, cloth, innertubes and rubber paint. Inside the tubes were a series of mirrors, each on a motorized balancing machine.

In the center of the shack was the interferometer, which Michelson sometimes called his "she devil." At the heart of the machine, a wheel covered with finely-honed mirrors spun at exactly 512 revolutions per second. When light struck this wheel, it bounced back and forth through the tunnel, eventually returning to the spot it had started from. By then the mirror would have changed its angle slightly, reflecting the light at an angle. By knowing the distance the light had traveled, the speed of the mirror and the angle of the bounce, Michelson could calculate the speed of light.

Clark remembers that the shack was "absolutely spotless" inside. While the experiment was running, her father often would drive house guests over to look at the shack- when he wasn't driving them to the other side of the ranch, where battle scenes were being shot for the film "All Quiet on the Western Front." Once, towards the end of the experiment, she says Michelson asked her to come inside, to look through a window that showed the length of the tube.

"It was very dark," she said. "I looked in the window and saw a long, dark hole that disappeared into nothing. There were little tiny sparks shooting back and forth. I'd never seen anything like it."

Michelson's last experiment did not go smoothly. On the day of his arrival, the pump being used to suck air out of the pipe broke down, halting the project. Leaks in the pipe were a regular problem, and fears of an earthquake were persistent. Michelson and his assistants fought over details.

His daughter described one of those fights, in which an assistant drove to Pasadena and called the physicist to the lobby of the Hotel Maryland. The two men stood in the lobby arguing with each other, wearing pajamas, scribbling diagrams on the back of a Chinese laundry ticket, until Michelson noticed that a crowd had gathered.

Michelson himself was not well. His health had begun to deteriorate years before, in what his doctor referred to as the "vile climate of Chicago," where Michelson had taught. His bladder was removed in 1929. The train trip to California exhausted him. His heart was weak and his circulation was slow. As the Orange County experiment progressed, he began to spend more and more time in bed, alert but physically weak.

Michelson got out of bed in April, 1931, when Einstein came to visit. Michelson's daughter remembers sitting between them at dinner, seeing that neither could keep his hair combed, and struggling to keep from laughing. The two men attended banquets together, and talked to each other privately.

At the end of April, Michelson's doctor confined him to his house, after suffering what the papers said was a nervous breakdown. In
early May, his assistants brought him early data from the tests. On May 9, Michelson suffered a stroke, followed by a cerebral hemorrhage. After lingering in a coma for several hours, he died.

The Register of Orange County, California ran the obituary on page 1.

Why would a dying man attempt an experiment as ambitious as Michelson's in Orange County?

R.S. Shankland, a leading historian of physics, believes Michelson came to Santa Ana to look one last time for the ether that had been so central to the science of his youth.

The final report on the Irvine Ranch experiments was published in 1933. The findings were extremely close to those accepted today, but many physicists consider the results of the tests on Mount Wilson more accurate. Some of the metal tubing now is used as drainage pipes at the Mount Wilson observatory.

There are markings at the site of the test, and though a nearby street was named in Michelson. s honor, it is commonly mispronounced. The Irvine Company has been sold and resold. James Irvine's mansion burned to the ground and was abandoned. If the vacuum tube were rebuilt on its old site today, it would run through the parking lot of a Home Club and the lobbies of two manufacturing firms on Armstrong Avenue in Irvine.

Wuerker, a UCLA physicist, thinks Michelson's work in Orange County is worth more than that. For one thing, he says, Michelson can be thought of as the man who gave this country a scientific tradition, on the day he won the Nobel Prize.

Even though Michelson's work here is not widely recognized, Orange County has become a hotbed for experimental physics. At the University of California, Irvine, this work is helping push physics beyond the edge of Einstein's world.

And in several of those experiments, UCI scientists are investigating incredibly small particles that move near the speed of light. These particles have no affect on the speed of light, but they do appear everywhere, invisible and mysterious, like an ether.