of Contents]People old and young enjoy waxing nostalgic about and learning some of the history of early electronics.
Popular Electronics was published from October 1954 through April 1985. All copyrights (if any) are hereby acknowledged.
Einstein published his paper on Special Relativity in 1905 and on General Relativity in 1916.
Since that time, many experiments have been performed worldwide by scientists intent on both
proving and disproving Mr. Einstein. Laser and nuclear based timepieces have been improved for
precision and calculations refined to aid in the task. Nearly 100 years later, General
Relativity stands. Even the rigors of quantum mechanics has not toppled its precepts.
See all articles from
to Check Einstein
Dr. Harold Lyons examines the tubular heart of the atomic clock which will be rocketed into
space to test Einstein's two theories of relativity.
There once was a Miss Fanny Bright
Whose speed was much greater than light
She set out
In a relative way
And arrived the previous night
According to Einstein's
theory of relativity, if you were to travel in space for 20 years at the speed of light (186,000
miles per second), you would return to find the earth millions of years older. In the topsy-turvy
world of relativity, where space and time merge into one and the same thing, the average person
tends to be incredulous about the whole thing. But you can't argue about the existence of atomic
bombs - which were developed according to Einstein's "theories." And now a most critical check
of the special and general relativity theories is being planned.
Dr. Harold Lyons,
head of Hughes Aircraft's atomic physics department, is supervising the design of a 30-pound atomic
"clock" which will be rocketed into space to "keep time" as it orbits around the earth through
varying intensities of the earth's gravitational field. More accurate than any other time device
in existence, the atomic clock will lose or gain less than one second in a thousand years. It
bears no resemblance to an ordinary clock - having no arms or face - and in truth is more oscillator
than clock. It looks something like a foot-long electron tube.
Before being launched,
the atomic clock will be synchronized with a similar clock on the ground. Then, as it orbits through
space at 18,000 miles per hour, it will generate an alternating current at a frequency of 24 billion
cycles per second. For purposes of measurement, this extremely high frequency will be converted
to a frequency more convenient for use with earth-based laboratory instruments. This information
will then be radioed to earth and the time on the orbiting clock will be compared with the time
on the earth clock.
It is expected that the satellite clock will run slow in comparison
with the ground clock as it passes through orbits below 2000 miles because, according to the special
theory of relativity, motional effects should predominate below that altitude. Above 2000 miles,
the clock should run fast in order to bear out the general theory of relativity; at higher altitudes,
the effects of the earth's gravity will be less.
Since the effects of motion and
gravity are opposite, as the satellite goes through the 2000-mile point, they should cancel out
and the two clocks should agree. Thus both the special and general relativity theories will be
The importance of the experiment was pointed out by Dr. Lyons, who stated, "Any
experiment that puts the general theory of relativity on a firmer physical basis would spur much
significant work in the space and nuclear ages." With an actual clock-launching probably only
several years off, the entire scientific world eagerly awaits the results.