Antimatter Propulsion

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Antimatter Propulsion

Imagine an energy source that is more powerful than nuclear fission or even nuclear fusion . Antimatter-matter reactions could offer an amount of energy that is not comparable to today's energy sources. When particles of matter and particles of antimatter collide, large amounts of energy are produced as a by-product. Because matter can neither be created nor destroyed, it is turned into tremendous amounts of energy.

Antimatter is the exact opposite of normal matter. Whereas a proton is a positively-charged particle, its antimatter counterpart, called an antiproton, is negatively charged. The antimatter counterpart to the negatively-charged electron is the positron, which is positively charged. All of the sub-atomic particles' charges are reversed, forming antiatoms. These antiatoms were first theorized in 1928 by Paul A. M. Dirac, a British physicist. In 1932 the first antimatter particle was created in a laboratory experiment by Carl Anderson, who is credited with coining the word "positron." Speculation continued throughout the 1950s, but because of the complexity of creating these particles, astrophysicists were unable to produce antimatter atoms until the late 1990s.

Antimatter particles are difficult to produce because of their very nature. When a particle or atom of antimatter comes into contact with a particle or atom of normal matter, both are annihilated and energy is released. The synthesized antiatoms have lasted only 40 billionths of a second before their annihilation. The particles were accelerated at close to the speed of light. Antihydrogen is the simplest antimatter atom to produce, yet, that feat took decades of research and billions of dollars. Even the European Organization for Nuclear Research (CERN), the laboratory in which the experiment was performed, admitted that this method of creating antimatter is far too expensive and difficult to be subject to mass production. Instead, cheaper and faster methods must be developed to make antimatter more than a dream of the future.

Developing antimatter is worth the effort because the energy created by sustainable matter-antimatter reactions would be so powerful that many people believe that faster-than-light travel, or "warp speed," could be achieved. Other possible uses include powering long-term spaceflight for humans and probes.

The main hope for antimatter is that one day this energy source could be used as a fuel. Hydrogen would be annihilated with anti-hydrogen, and the energy would be funneled into a magnetic nozzle of a rocket . Such energy would propel the ship or probe at tremendous speeds compared to today's methods of propulsion. One of the problems with this model is that much of the energy is given off as neutrally charged particles that cannot be harnessed. To make use of the majority of the energy produced, these particles would have to be captured.

The amount of thrust produced by the space shuttle's boosters is equal to the energy released from 71 milligrams of antimatter. The benefits of antimatter propulsion will be worth the effort when this energy can be used to explore the universe in a way that has only been dreamed of so far.

see also Faster-Than-Light Travel (volume 4); Interstellar Travel (volume 4); Nuclear Propulsion (volume 4); Rockets (volume 3).

Craig Samuels

Bibliography

Barnett, Michael R., Henry Muehry, Helen R. Quinn, and Gordon Aubrecht. The Charm of Strange Quarks: Mysteries and Revolutions of Particle Physics. New York: AIP Press, 2000.