It would be interesting to know how many citizens of Maryland are aware of an experiment made in 1975-76, over a five-month period, to verify (or falsify) a prediction made by Albert Einstein about his theory of gravity. This experiment was directed by the University of Maryland. Until I read, “Einstein’s Universe” by Nigel Calder, I had never read or heard about this study in physics.
This book is intended to be a readable account of Einstein’s 1905 Special Relativity theory and his 1915 General Relativity theory rather than a personal biography. Honesty makes it necessary for me to admit that, while Calder is relatively successful in his goal of “readability,” relativity theory can be very incomprehensible.
The story of the five flights by a U.S. Navy anti-sub plane over the Chesapeake Bay had its origins in 1908 when Einstein predicted that the force of gravity would alter the performance of clocks. Sixty-seven years later, physicists at the University of Maryland would conduct an experiment that would confirm Einstein’s theory. As Calder declares “the operation showed, very simply, that time depends on where you are and clocks run more slowly at ground level than they do in aircraft flying in the weaker gravity high above the earth.”
One marvels at the sophistication of the measurement procedure used to establish the finding in this study. Two sets of clocks — each using three very sensitive clocks — were employed to compare the readings in the plane, flying at an altitude of 30,000 feet, with the other set on the ground. The clocks carried by the plane gained about three billionths of a second every hour. The increase in the time rate of the clocks in the plane confirmed Einstein’s prediction to within about 1 percent. Maryland deserves credit for this contribution to physics.
Earlier I have called attention to another prediction important to Einstein’s 1915 General Relativity theory. At this point in time, Einstein had concluded that light was made up of tiny particles which he called photons. Since these particles had mass, he then predicted that light passing near the sun would be effected by its gravitational pull. This was confirmed in 1919 in a truly remarkable series of observations in Brazil and West Africa under the direction of scientists from Great Britain.
Einstein’s reputation was at its peak when he wrote his now famous letter to President Roosevelt in 1939 apprising him of the advances in atomic fission and that Germany might take the lead in adapting this knowledge to military uses. Roosevelt acted promptly with the creation of the Manhattan Project which resulted in the development of an atomic bomb.
There is sadness in the accounts of Einstein’s friendly parting from his younger friends in quantum physics as they probed the world of tiny particles. Einstein had always been a strong believer in the invariant action of cause and effect in natural events. When quantum physicists introduced the theory called the “uncertainty principle” to be operable at the sub-atomic level, Einstein made his much quoted remark that “God does not play dice” with nature.
Even such geniuses as Albert Einstein and Sir Isaac Newton are left behind as science relentlessly covers new ground. As I was reading Calder’s fine book, on Dec. 13, an announcement was made that scientists were on the verge of confirming the discovery of another sub-atomic particle that is already named the Higgs boson particle. They are fortunate to have a truly amazing bit of technology that stretches 17 miles underground to aid in particle experiments. Einstein would be in awe of these advances.
There is much to be learned and appreciated about science coming out of this little known story about a single airplane and some clocks used in flights over the Chesapeake Bay. It shows the importance of open sharing of the thinking and progress of scientists around the world as they search for the secrets of nature. Science thrives on honest diversity of opinion, personal talents and personality.
From all of this mix, a filtering takes place which results in the accumulation of reliable knowledge to improve our lives.
Allan Powell is professor emeritus of philosophy at Hagerstown Communtiy College.