The term "anti-electron" first appeared in an article by Dirac in 1931. But not even Dirac himself seemed to have complete confidence in his theory. He left it unclear as to whether he was referring to a truly detectable particle. To Dirac, it must have seemed too preposterous to postulate the existence of an entire anti-world solely on the basis of a formula. Dirac was later asked why he hadn't clearly predicted the new particle at the time. "Pure cowardice," he replied.
Even when Carl Anderson, a 26-year-old American, made his great discovery, it went almost unnoticed in the scientific community at first. In the air-and-alcohol mixture of a cloud chamber, Anderson had seen strange strips of condensation that looked as if they came from positively charged electrons. But no one drew the conclusion that these could have been the anti-electrons Dirac had described.
The breakthrough came in a lecture at the Royal Society in London, where the results from the United States were presented. The audience was mesmerized by photos of the ghostlike particle trails. It seemed as if messengers from the depths of the universe were raining down on planet Earth. Upon impact, they created particle-antiparticle pairs that disappeared into nothingness shortly thereafter.
The most elementary form of creation and destruction was unfolding before the eyes of the audience. The speaker, Patrick Blackett, called it the "death pact."
Fuelling the Imagination A new element entered the world of science fiction on that day. The term "anti-world" alone is enough to inspire fantasies, suggesting the possibility of another, opposite form of existence. Heaven and hell, Christ and Antichrist, matter and antimatter -- could there be a connection?
But antimatter is also fascinating beyond all metaphysical speculation, especially as it reveals the full explosive force of Einstein's famous formula, E = mc2. Mass, as the equation states, is nothing but highly concentrated energy. Normally, however, that energy is "trapped" in the form of matter. But when a particle and its antiparticle collide, this energy is released immediately -- and in an impressive quantity. About a teaspoon of matter, combined with the corresponding amount of antimatter, is enough to unleash the destructive power of the Hiroshima bomb.
Not surprisingly, antimatter usually plays either the role of a super-fuel or a super-bomb in the utopias of science fiction authors. Either power-hungry extraterrestrials are destroying planets with their antimatter cannons, or megacities are slurping all of their energy from small tubes of antimatter. In his novel "Angels & Demons," the author Dan Brown describes a hunt for a canister of antimatter with which the secret society of the Illuminati plans to destroy the Vatican. And the fictional starship USS Enterprise of "Star Trek" fame can only embark on its expeditions to distant civilizations because antimatter is fueling its warp drive.
Physicists, however, have never nourished any great hopes of being able to make such visions reality. That's because they know that all the world's antiproton factories combined produce less than a billionth of a gram of antimatter per year. At this rate, they would have had to start production well before the Big Bang to make a single super-bomb -- not to mention the problem of having to store the antimatter for such a long time without triggering a premature explosion.