as we that are left grow old,

age shall not wither them

nor the years condemn;

At the going down of the sun

and in the morning,

we shall remember them .

- Tomb of the

Scottish Unknown Soldier

Edinburgh

PAUL DIRAC, ANTIMATTER, AND YOU

A Riddle

What have these in common?

1. 1926: A graduate student, Cambridge University

2. Billions of years ago: Quasars exploding

3. 1908: A Siberian forest devastated

4. 10 million years ago: A galaxy exploding

5. 1932: A cloud - chamber track, Pasadena, Calif.

Answer: All may, and 1 and 5 do involve antimatter.

(ANTI matter?)

Yes - like ordinary matter with electrical properties of particles reversed. Each atom of matter is one or more nucleons surrounded by one or more electrons; charges add up to zero. A hydrogen atom has a proton with positive charge as nucleus, surrounded by an electron with negative charge. A proton is 1836.11 times as massive as an electron, but their charges are equal and opposite: + 1 - 1 = 0. Uranium - 235 (or U235, meaning "an isotope of element 92, uranium, nuclear weight 235") has 235 nucleons: 143 neutrons of zero charge and 92 protons of positive charge (143 + 92 = 235; hence its name); these 235 are surrounded by 92 electrons (negative), so total charge is zero: 0 +92 - 92 = 0. (Nuclear weight is never zero, being the mass of all the nucleons.)

Make electrons positive, protons negative: charges still balance; nuclear weight is unchanged - but it is not an atom of matter; it is an antiatom of antimatter. "Touch Me Not!"

In an antimatter world, antimatter behaves like matter. Bread dough rises, weapons kill, kisses still taste sweet. You would be antimatter and not notice it.

WARNING! Since your body is matter (else you could not be reading this), don't kiss an antimatter girl. You both would explode with violence unbelievable.

But you'll never meet one, nor will your grandchildren. (I'm not sure about their grandchildren.) E = mc2

Antimatter is no science - fiction nightmare; it's as real as Texas. That Cambridge graduate student was Paul A. M. Dirac inventing new mathematics to merge Albert Einstein's special theory of relativity with Max Planck's quantum theory. Both theories worked - but conflicted. Dirac sought to merge them without conflict.

He succeeded.

His equations were published in 1928, and from them, in 1930, he made an incredible prediction: each sort of particle had antiparticles of opposite charge: "antimatter."

Scientists have their human foibles; a scientist can grow as fond of his world concept as a cat of its "own" chair. By 1930 the cozy 19th - century "world" of physics had been repeatedly outraged. This ridiculous new assault insulted all common sense.

But in 1932 at the California Institute of Technology, Carl D. Anderson photographed proof of the electron's antiparticle (named "positron" for its positive charge but otherwise twin to the electron). Radical theory has seldom been confirmed so quickly or re warded so promptly: Dirac received the Nobel prize in 1933, Anderson in 1936 - each barely 31 years of age when awarded it.

Since 1932 so many sorts of antiparticles have been detected that no doubt remains: antimatter matches matter in every sort of particle. Matching is not always as simple as electron (e - ) and positron (e+). Photons are their own antiparticles. Neutrons and neutrinos (zero charges) are matched by antineutrons and antineutrinos, also of zero charge - this sounds like meaningless redundancy because English is not appropriate language; abstract mathematics is the language required for precise statements in physical theory. (Try writing the score of a symphony solely in words with no musical symbols whatever.)

But a hint lies in noting that there are reaction series in which protons and electrons yield neutrons - one example: solar power theory, Hans Bethe; if we ignore details, the Solar Phoenix can be summarized as changing four hydrogen atoms (four of 1Ht) into one helium atom (2H4). We start with four protons and four electrons; we end up six stages later with two neutrons, two protons, and two electrons - and that is neither precise nor adequate and is not an equation and ignores other isotopes involved, creation of positrons, release of energy through mutual annihilations of positrons and free electrons, and several other features, plus the fact that this transformation can occur by a variety of routes.

Nevertheless, antimatter is scarce in our corner of the universe - lucky for us because, when matter encounters antimatter, both explode in total annihilation. E = mc2 is known to everyone since its awful truth was demonstrated at Hiroshima, Japan. It states that energy is equivalent to mass, mass to energy, in this relation: energy equals mass times the square of the velocity of light in empty space.

That velocity is almost inconceivable. In blasting for the moon our astronauts reached nearly 7 miles! second; light travels almost 27,000 times that speed - 186,282.4 (±0.1) miles or 299,792.5 (±0.15) kilometers each second. Round off that last figure as 300,000; then use the compatible units of science (grams, centimeters, ergs) and write in centimeters 3 x 1O °, then square it: 9 x 1020, or 900000,000,000000000,000. (!!!)

This fantastic figure shouts that a tiny mass can become a monstrous blast of energy - grim proof: Hiroshima.

But maximum possible efficiency of U23 fission is about 1/10 of 1%; the Hiroshima bomb's actual efficiency was much lower, and H - bomb fusion has still lower maximum (H - bombs can be more powerful through having no limit on size; all fission bombs have sharp limits). But fission or fusion, almost all the reacting mass splits or combines into other elements; only a trifle becomes energy.

In matter - antimatter reaction, however, all of both become energy.

Mathematical Physicists

An experimental physicist uses expensive giant accelerators to shoot particles at 99.9% of the speed of light, or sometimes gadgets built on his own time with scrounged materials. Large or small, cheap or costly, he works with things.

A mathematical physicist uses pencil, paper, and brain. Not my brain or yours - unless you are of the rare few with "mathematical intuition."

That's a tag for an unexplainable. It is a gift, not a skill, and cannot be learned or taught. Even advanced mathematics ("advanced" to laymen) such as higher calculus, Fourier analysis, n - dimensional and non - Euclidean geometries are skills requiring only patience and normal intelligence .. . after they have been invented by persons having mathematical intuition.

The oft - heard plaint "I can't cope with math!" may mean subnormal intelligence (unlikely), laziness (more likely), or poor teaching (extremely likely). But that plaint usually refers to common arithmetic - a trivial skill in the eyes of a mathematician. (Creating it was not trivial. Zero, positional notation, decimal - or base point all took genius; imagine doing a Form 1040 in Roman numerals.)

Of billions living and dead perhaps a few thousand have been gifted with mathematical intuition; a few hundred have lived in circumstances permitting use of it; a smaller fraction have been mathematical physicists. Of these a few dozen have left permanent marks on physics.

But without these few we would not have science. Mathematical physics is basic to all sciences. No exceptions. None.

Mathematical physicists sometimes hint that experimentalists are frustrated pipe fitters; experimentalists mutter that theoreticians are so lost in fog they need guardians. But they are indispensable to each other. Piling up facts is not science - science is facts and - theories. Facts alone have limited use and lack meaning; a valid theory organizes them into far greater usefulness. To be valid a theory must be confirmed by all relevant facts. A "natural law" is theory repeatedly confirmed and drops back to "approximation" when one fact contradicts it. Then search resumes for better theory to embrace old facts plus this stubborn new one.