Expanded Universe (58 page)

Dirac brought this attitude to theoretical physics; his successes justify his approach.

He was born in Bristol, England, Aug. 8, 1902, and named Paul Adrien Maurice Dirac. His precocity in mathematics showed early; his father supplied books and encouraged him to study on his own. Solitary walks and study were the boy's notion of fun—and are of the man today. Dirac works (and plays) hardest by doing and saying
nothing . . . 
while his mind roams the universe.

When barely 16 years old, he entered the University of Bristol. At 18 he graduated, bachelor of science in electrical engineering. In 1923 a grant enabled him to return to school at the foremost institution for mathematics, Cambridge University. In three years of study for a doctorate Dirac published 12 papers in mathematical physics, 5 in
The Proceedings of the Royal Society.
A cub with only an engineering degree from a minor university has trouble getting published
in any
journal of science; to appear at the age of 22 in the most highly respected of them all is amazing.

Dirac received his doctorate in May 1926, his dissertation being "Quantum 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 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 Lemaître'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 10
¹⁰
per annum). This amount seems trivial, but it is
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.

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 antimatter. Others find that setup dangerously crowded—make it every second galaxy. Still others prefer universe-and-antiuniverse with antimatter in ours only on rare occasions when energetic particles collide so violently that some of the energy forms antiparticles. And some like higher numbers of universes—even an unlimited number.

One advantage of light's finite speed is that we can see several eons of the universe in action, rather than just one frame of a
very
long moving picture. Today's instruments reach not only far out into space but also far back into time; this permits us to test in some degree a proposed cosmology. The LST (Large Space Telescope), to be placed in orbit by the Space Shuttle in 1983, will have 20 times the resolving power of the best ground-based and atmosphere-distorted conventional telescope—therefore 20 times the reach, or more than enough to see clear back to the "beginning" by one cosmology, the "big bang."

(Q: What happened
before
the beginning? A:
You
tell
me.)
 

When we double that reach—someday we will—what will we see? Empty space? Or the backs of our necks?

(Q: What's this to
me
?
A: Patience one moment. . . .)

The star nearest ours is a triplet system; one of the three resembles our sun and may have an Earthlike planet—an inviting target for our first attempt to cross interstellar space. Suppose that system is antimatter—
BANG!
Scratch one starship.

(Hooray for Zero Population Growth! To hell with space-travel boondoggles!)

Then consider this: June 30, 1908, a meteor struck Siberia, so blindingly bright in broad daylight that people 1,000 miles away saw it. Its roar was "deafening" at 500 miles. Its ground quake brought a train to emergency stop 400 miles from impact. North of Vanavara its air blast killed a herd of 1,500 reindeer.

Trouble and war and revolution—investigation waited 19 years. But still devastated were many hundreds of square miles. How giant trees lay pinpointed impact.

A meteor from inside our Galaxy can strike Earth at 50 miles/second.

But could one hit us from
outside
our Galaxy?

Yes!
The only unlikely (but not impossible) routes are those plowing edgewise or nearly so through the Milky Way; most of the sky is an open road—step outside tonight and
look.
An antimeteor from an antigalaxy could sneak in through hard vacuum—losing an antiatom whenever it encountered a random atom but nevertheless could strike us massing, say, one pound.

One pound
of antimatter at any speed or none would raise as much hell as
28,000 tons
of matter striking at 50 miles/second.

Hubble Large Space Telescope

Today no one knows how to amass even a gram of antimatter or how to handle and control it either for power or for weaponry. Experts assert that all three are impossible.

However . . .

Two relevant examples of "expert" predictions:

Robert A. Millikan, Nobel laureate in physics and distinguished second to none by a half-century of research into charges and properties of atomic particles, in quantum mechanics, and in several other areas, predicted that all the power that could ever be extracted from atoms would no more than blow the whistle on a peanut vendor's cart. (In fairness I must add that most of his colleagues agreed—and the same is true of the next example.)

Forest Ray Moulton, for many years top astronomer of the University of Chicago and foremost authority in ballistics, stated in print (1935) that there was "not the slightest possibility of such a journey" as the one the whole world watched 34 years later: Apollo 11 to the moon.

 

In 1908 the Tunguska region of Siberia was struck by a blast equivalent to 30 million tons of TNT, the impact of which was felt by residents 400 miles from the site and which left in its wake a 20-mile radius of charred forests. Numerous theories attempting to explain the occurrence have been suggested over the years, but none has gained consensus in the scientific community. Among the more recent theories to explain the blast is the proposal that an antimeteor, composed of antimatter, plunged through Earth's atmosphere and upon coming in contact with ordinary matter exploded with devastating force.

In 1938, when there was not a pinch of pure uranium-235 anywhere on Earth and no technology to amass or control it, Lise Meitner devised mathematics that pointed straight to atom bombs. Less than seven years after she did this, the first one blazed "like a thousand suns."

No
possible
way to amass antimatter?

Or
ever
to handle it?

Being smugly certain of
that
(but mistaken) could mean to
you . . . 
and me and everyone . . .

The
END
 

I am precluded from revising this article because Encyclopaedia Britannica owns the copyright; I wrote it under contract. But in truth it needs no revision but can use some late news flashes. 
1) Jonathan V. Post reports (Onmi, May '79) that scientists in Geneva have announced containment of a beam of antiprotons in a circular storage ring for 85 hours. Further deponent sayeth not as today (Nov. '79) I have not yet traced down details. The total mass could not have been large (Geneva is still on the map) as the storage method used is not suited to large masses—or, as in this case, a massive sum total of very small masses. 
But I am astonished at any containment even though with dead seriousness I predicted it in the section just above. I did not expect it in the near future but now I learn it happened at least 10 months ago, only 4 years after I wrote the above article. 
Too frighteningly soon! A very small (anti) mass to be sure—but when Dr. Lise Meitner wrote the equations that implicitly predicted the A-bomb, there was not enough purified U-235 anywhere to cause a gnat's eye to water. 
How soon will we face a LARGE mass—say about an ounce—planted in Manhattan by someone who doesn't like us very well? If he releases the magnetic container by an alarm-clock timer or nine other simple make-it-in-your-own-kitchen devices, he can be in Singapore when it goes off. Or in Trenton if he enjoys watching his own little practical jokes—he won't worry about witnesses; they will be dead. 
Too big? Too cumbersome? Too expensive? I don't know—and neither does anyone else today. I am not proposing sneaking a CERN particle accelerator past Hoboken customs . . . but note that the first reacting atomic pile (University of Chicago) was massive—but it was not flown to Hiroshima. The bomb that did go was called "Little Boy" for good reason. Now we can fire them from 8-inch guns. As for the "suitcase" bomb—change that to a large briefcase; all the other essentials can be bought off the shelf for cash in any medium-large city, no questions asked as they are commonplace items. 
Antimatter, containment and all, might turn out to be even smaller, lighter, simpler. 
 

2) That variable constant: Dr. Van Flandern is still plugging away at Dr. Dirac's 1937 prediction about the "Constant" of Gravitation. The latest figures I have seen show (by his measurements) that the "Constant" is decreasing by 3.6 ± 1.8 parts in 1011 years, a figure surprisingly close to Dirac's 1937 prediction (5.6) in view of the extreme difficulty of making the measurements and of excluding extraneous variables. But all this is based on a universe 18–20 billion years old since the "big bang"—an assumption on current best data but still an assumption. If the universe is actually materially older than that (there are reasons to think so, and all the revisions since Abbé Lemaître first formulated the theory have all been upward, never downward), then Dirac's prediction may turn out to be right on the nose of observed data to their limit of accuracy. 
The data above are from an article by Dr. Herbert Friedman of Naval Research Laboratory. Our Baker Street Irregulars have just established a pipeline to Dr. Van Flandern; if major new data become available before this book is closed for press, I will add a line to this. 
3) In Where To see prediction number fourteen, page 276: At the Naval Academy I slept my way through the course in physics; nothing had changed since I had covered the same ground in high school. "Little did I dream" that a young man at Cambridge, less than five years older than I, was at that very moment turning the world upside down. This quiet, polite, soft-spoken gentleman was going to turn out to be the enfant terrible of physics. This has been the stormiest century in natural philosophy of all history and the storms are not over. We would not today have over 200 "elementary" particles (an open scandal) if Paul Dirac had not simplified the relation of spin and magnetism in an electron into one equation over fifty years ago, then shown that the equation implied antimatter. 
Many thousands of man-hours, many millions of dollars have been spent since then exploring the byways opened up by this one equation. And the end is not yet. The four forces (strong, weak, gravitic, electromagnetic) are still to be combined into one system. Einstein died with the work unfinished, Hawking (although young) is tragically ill, Dirac himself has reached the age when he really should not climb stepladders (as I know too well; I'm not that much younger). 
E = mc2 everybody knows; it's short and simple. But the Dirac equation, at least as important, is known only to professionals—not surprising; it's hairy and uses symbols a layman never sees. 
I include it here just for record; I won't try to explain it. For explanations, get a late text on quantum mechanics and be prepared to learn some not-easy mathematics. Lotsa luck!