Antimatter is the opposite of normal matter, of which the majority of our universe is made. Until just recently, the presence of antimatter in our universe was considered to be only theoretical. In 1928, British physicist Paul A.M. Dirac revised Einstein’s famous equation E=mc². Dirac said that Einstein didn’t consider that the “m” in the equation — mass — could have negative properties as well as positive. Dirac’s equation (E = + or – mc2) allowed for the existence of anti-particles in our universe. Scientists have since proven that several anti-particles exist.
These anti-particles are, literally, mirror images of normal matter. Each anti-particle has the same mass as its corresponding particle, but the electrical charges are reversed. Here are some antimatter discoveries of the 20th century:
Positrons – Electrons with a positive instead of negative charge. Discovered by Carl Anderson in 1932, positrons were the first evidence that antimatter existed.
Anti-protons – Protons that have a negative instead of the usual positive charge. In 1955, researchers at the Berkeley Bevatron produced an antiproton.
Anti-atoms – Pairing together positrons and antiprotons, scientists at CERN, the European Organization for Nuclear Research, created the first anti-atom. Nine anti-hydrogen atoms were created, each lasting only 40 nanoseconds. As of 1998, CERN researchers were pushing the production of anti-hydrogen atoms to 2,000 per hour.
When antimatter comes into contact with normal matter, these equal but opposite particles collide to produce an explosion emitting pure radiation, which travels out of the point of the explosion at the speed of light. Both particles that created the explosion are completely annihilated, leaving behind other subatomic particles. The explosion that occurs when antimatter and matter interact transfers the entire mass of both objects into energy. Scientists believe that this energy is more powerful than any that can be generated by other propulsion methods.
E = mc2
Einstein’s famous formula means that ‘mass is condensed energy’. Since ‘c’ is the speed of light, which is a very large number, the equation tells us that a small amount of mass contains an enormous amount of energy. It is like exchanging money between different currencies, with a huge exchange rate.
A mass of 1 kg contains an energy of 90 million gigajoules, equivalent to worldwide energy consumption over 90 minutes.
When antiparticles and particles meet, they destroy each other. This process, called ‘annihilation’, liberates all the energy that is stored in their mass. Annihilation can create gamma-rays or even new particle-antiparticle pairs.
There is technology available to create antimatter through the use of high-energy particle colliders, also called “atom smashers.” Atom smashers, like CERN, are large tunnels lined with powerful supermagnets that circle around to propel atoms at near-light speeds. When an atom is sent through this accelerator, it slams into a target, creating particles. Some of these particles are antiparticles that are separated out by the magnetic field. These high-energy particle accelerators only produce one or two picograms of antiprotons each year. A picogram is a trillionth of a gram. All of the antiprotons produced at CERN in one year would be enough to light a 100-watt electric light bulb for three seconds. It will take tons of antiprotons to travel to interstellar destinations.
Antimatter at lower energies is used in Positron Emission Tomography . But antimatter has captured public interest mainly as fuel for the fictional starship Enterprise on Star Trek. In fact, NASA is paying attention to antimatter as a possible fuel for interstellar propulsion. At Penn State University, the Antimatter Space Propulsion group is addressing the challenge of using antimatter annihilation as source of energy for propulsion.