Heinlein, Robert A – Expanded Universe

Out of sight around the curve a train whistled. Perhaps there would have

been time to run and flag it down, perhaps not. In any case both men went right

ahead trying to pull her free . . . and the train hit them.

The wife was killed, the husband was mortally injured and died later, the

tramp was killed-and testimony showed that neither man made the slightest effort to

save himself.

The husband’s behavior was heroic . . but what we expect of a husband toward

his wife: his right, and his proud privilege, to die for his woman. But what of this

nameless stranger? Up to the very last second he could have jumped clear. He did

not. He was still trying to save this woman he had never seen before in his life,

right up to the very instant the train killed him. And that’s all we’ll ever know

about him.

This is how a man dies.

This is how a man .. . lives!

“They shall not grow old

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

Page 195

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 ~2U~35, 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