Mechanics”-the stickiest
subject in physical science. He tackled it his first year at Cambridge and has
continued tO unravel its paradoxes throughout his career; out of 123 publications
over the last 50 years the word quantum can be found 45 times in his titles.
Dirac remained at Cambridge-taught, thought, published. In 1932, the year
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before his Nobel prize, he received an honor rarer than that prize, one formerly
held by Newton: Lucasian professor of mathematics. Dirac kept it 37 years, until he
resigned from Cambridge. He accepted other posts during his Cantabrigian years:
member of the Institute for Advanced Study at Princeton, N.J., professor of the
Dublin Institute for Advanced Studies, visiting professorships here and there.
Intuitive mathematicians often burn out young. Not Dirac!-he is a
Michelangelo who started very young, never stopped, is still going strong.
Antimatter is not necessarily his contribution most esteemed by colleagues, but his
other major ones are so abstruse as to defy putting them into common words:
A mathematical attribute of particles dubbed “spin”; coinvention of the
Fermi-Dirac statistics; an abstract mathematical replacement for the “pellucid
aether” of classical mechanics. For centuries, ether was used and its “physical
reality” generally accepted either as “axiomatic” or “proved” through various
negative proofs. Both “axiom” and “negative proof” are treacherous; the 1887
Michelson-Morley experiment showed no physical reality behind the concept of ether,
and many variations of that experiment over many years gave the same null results.
So Einstein omitted ether from his treatments of relativity-while less
brilliant men ignored the observed facts and clung to classical ether for at least
40 years.
Dirac’s ether (circa 1950) is solely abstract mathematics, more useful
thereby than classical ether as it avoids the paradoxes of the earlier concepts.
Dirac has
consistently warned against treating mathematical equations as if they were pictures
of something that could be visualized in the way one may visualize the Taj Mahal or
a loaf of bread; his equations are rules concerning space-time events-not pictures.
(This may be the key to his extraordinary successes.) One more example must
represent a long list:
Dirac’s work on Georges Lemaltre’s “primeval egg”- later popularized as the “big
bang.”
Honors also are too many to list in full: fellow of the Royal Society, its
Royal Medal, its Copley Medal, honorary degrees (always refused), foreign associate
of the American Academy of Sciences, Oppenheimer Memorial Prize, and (most valued by
Dirac) Great Britain’s Order of Merit.
Dirac “retired” by accepting a research professorship at Florida State
University, where he is now working on gravitation theory. In 1937 he had theorized
that Newton’s “constant of gravitation” was in fact a decreasing variable . . . but
the amount of decrease he predicted was so small that it could not be verified in
1937.
Today the decrease can be measured. In July 1974 Thomas C. Van Flandern of
the U.S. Naval Observatory reported measurements showing a decrease in gravitation
of about a ten-billionth each year (1 per 1010 per annum). This amount seems
trivial, but it j~ very large in astronomical and geological time. If these findings
are confirmed and if they continue to support Dirac’s mathematical theory, he will
have upset physical science even more than he did in 1928 and 1930.
Here is an incomplete list of the sciences that would undergo radical
revision: physics from micro- through astro-, astronomy, geology, paleontology,
meteorology, chemistry, cosmology, cosmogony, geogony, ballistics. It is too early
to speculate about effects on the life sciences, but we exist inside this physical
world and gravitation is the most pervasive feature of our world.
Theory of biological evolution would certainly be affected. It is possible
that understanding gravitation could result in changes in engineering technology too
sweeping easily to be imagined.
Antimatter and You
Of cosmologies there is no end; astrophysicists enjoy “playing God.” It’s
safe fun, too, as the questions are so sweeping, the data so confusing, that any
cosmology is hard to prove or disprove. But since 1932 antimatter has been a
necessary datum. Many cosmologists feel that the universe (universes?) has as much
antimatter as matter-but they disagree over how to balance the two.
Some think that, on the average, every other star in our Milky Way galaxy is