Scientists Say: Antimatter

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Antimatter (noun, “AN-tee-MAT-ter”)

Antimatter is made of antiparticles. Think of antiparticles like partners of ordinary particles, but with the opposite properties.

You’ve likely heard of protons, neutrons and electrons. These are the tiny particles that make up atoms. But you may not have heard of their anti-twins. These are antiprotons, antineutrons and positrons.

Particles and antiparticles have the same mass. But they generally have opposite electric charges. An electron is negative. So the positron is positive. A proton is positive. So the antiproton is negative. But exceptions to law of opposites exist. Take the neutron, which has no electric charge. It’s neutral. So the antineutron is also neutral.

When matter and antimatter meet, they destroy each other. If an electron meets a positron, for instance, they self-destruct. As physicists say, they “annihilate” each other. This releases energy in the form of gamma rays. That’s a high-energy type of light.

Antiparticles can bind together to form atoms, just as ordinary particles do. Scientists have built antihydrogen in the lab. They do that by pairing a positron and an antiproton. This isn’t an easy feat, though. If either of those antiparticles touch ordinary matter — poof! They cease to exist. That means scientists must “handle” the particles without touching them. They do this through magnetic or electrical fields.

Very, very little antimatter exists today. A tiny amount occurs naturally. For example, cosmic rays constantly smash into Earth’s atmosphere. When they do, they produce tiny bits of antimatter. Some radioactive decay gives off antiparticles, too. But antimatter never lasts very long. Normal matter quickly destroys it.

Scientists believe that the Big Bang produced equal amounts of matter and antimatter. Why does ordinary matter reign supreme today? That’s one of the universe’s biggest mysteries.