5 Amazing Facts About Antimatter

Antimatter is science fiction. In the book and movie Angels and Demons, Professor Langdon tries to save the Vatican from an antimatter bomb. The starship Enterprise from Star Trek uses the destruction of matter and antimatter to travel faster than light.

But antimatter is also a matter of reality. Antimatter particles are almost identical to their matter counterparts, except that they carry the opposite charge and spin. When antimatter meets matter, it instantly annihilates into energy.

While antimatter bombs and antimatter-powered spaceships are far-fetched, there are still plenty of facts about antimatter that will tickle your brain cells.

 Antimatter was supposed to destroy all matter in the universe after the big bang.

According to the theory, the big bang should have created matter and antimatter in equal amounts. When matter and antimatter meet, they annihilate, leaving nothing but energy behind. So basically none of us should exist.

But we do. And as far as physicists can tell, it's only because eventually there was one extra particle of matter for every billion pairs of matter and antimatter. Physicists are working hard to explain this asymmetry.

 Antimatter is closer to you than you think.

Small amounts of antimatter are constantly raining down on Earth in the form of cosmic rays, energetic particles from space. These antimatter particles enter our atmosphere at rates ranging from less than one per square meter to more than 100 per square meter. Scientists have also seen evidence of antimatter production above storms.

But other sources of antimatter are even closer to home. Bananas, for example, produce antimatter and release one positron—the antimatter equivalent of an electron—about every 75 minutes. This occurs because bananas contain small amounts of potassium-40, a naturally occurring isotope of potassium. As potassium-40 decays, it sometimes spits out a positron.

Our bodies also contain potassium-40, which means that positrons are emitted from you as well. Antimatter annihilates immediately upon contact with matter, so these antimatter particles have very short lifetimes.

 Humans have created only a tiny amount of antimatter.

The annihilation of antimatter and matter have the potential to release enormous amounts of energy. A gram of antimatter could cause an explosion the size of a nuclear bomb. However, humans produced only a tiny amount of antimatter.

All the antiprotons created at Fermilab's Tevatron particle accelerator have a combined weight of just 15 nanograms. Those produced at CERN reach around 1 nanogram. Around 2 nanograms of positrons have been produced at DESY in Germany so far.

If all the antimatter that humans have ever produced were destroyed at once, the energy produced would not even be enough to make a cup of tea.

The problem lies in the efficiency and cost of producing and storing antimatter. Producing 1 gram of antimatter would require approximately 25 million billion kilowatt hours of energy and cost over a million billion dollars.

 There is such a thing as an antimatter trap.

To study antimatter, you must prevent it from annihilating with matter. Scientists have developed ways to do this.

Charged antimatter particles such as positrons and antiprotons can be held in devices called Penning traps. These are comparable to small accelerators. Inside, the particles spiral around as the magnetic and electric fields prevent them from colliding with the walls of the trap.

But Penning traps won't work on neutral particles like antihydrogen. Because they have no charge, these particles cannot be confined by electric fields. Instead, they are held in Ioffe traps, which work by creating a region of space where the magnetic field increases in all directions. The particle gets stuck in the area with the weakest magnetic field, much like a marble rolling along the bottom of a bowl.

Earth's magnetic field can also act as a kind of antimatter trap. Antiprotons have been found in zones around Earth called the Van Allen radiation belts.

 Antimatter can fall.

Antimatter and matter particles have the same mass but differ in properties such as electric charge and spin. The Standard Model predicts that gravity should have the same effect on matter and antimatter; however, that remains to be seen. Experiments like AEGIS, ALPHA and GBAR are trying to find out.

Observing the effect of gravity on antimatter is not as easy as observing an apple fall from a tree. These experiments need to trap antimatter or slow it down by cooling it to temperatures just above absolute zero. And since gravity is the weakest of the fundamental forces, physicists must use neutral antimatter particles in these experiments to prevent interference from the stronger electric force.

 Conclusion

There is currently no technology available to mass produce or collect antimatter in the volume required for this application. However, a small number of researchers have performed simulation studies on propulsion and storage. They include Ronan Keane and Wei-Ming Zhang, who worked at Western Reserve Academy and Kent State University, respectively, and Marc Weber and his colleagues at Washington State University. One day, if we can figure out a way to create or collect large amounts of antimatter, their studies could help make antimatter-powered interstellar travel a reality.