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Antimatter

physical science Maturity 7-9 Next article →

Everything in our world is made of matter. But there is a special twin called antimatter.

PositronDiscovery
PositronDiscovery

Antimatter is made of antiparticles. These are partners to the particles in normal matter. They have the same mass. However, they have an opposite electric charge. For example, an electron has a negative charge. Its twin is the positron, which has a positive charge. An antiproton is negatively charged, while a proton is positive. This makes antimatter a very different kind of building block.

When matter and antimatter meet, they crash together. This event is called annihilation. During annihilation, both particles turn into pure energy. This energy often comes out as gamma rays. These are very strong types of light.

16slicePETCT
16slicePETCT

If there is matter nearby, the energy turns into heat or light. This process follows a rule called mass-energy equivalence. It means the energy released depends on the mass of the particles. This powerful reaction is how antimatter works.

Scientists have studied these particles for a long time. The modern theory began in 1928 with Paul Dirac. He wrote a paper about how electrons work. J. Robert Oppenheimer later argued that a positive electron must exist. This particle is the positron. Carl D. Anderson discovered the positron in 1932.

PositronDiscovery
PositronDiscovery

Later, teams used the Bevatron in Berkeley, California, to find more. They found the antiproton in 1955 and the antineutron in 1956. These discoveries changed how we see the world.

Making antimatter is a very hard job. Scientists can only make a tiny amount at particle accelerators. Total production has only been a few nanograms. It is also very expensive to handle. We cannot collect large amounts of it.

16slicePETCT
16slicePETCT

Even so, we use it in medicine every day. Doctors use positron emission tomography to see inside the body. They also use it for radiation therapy and industrial imaging. These tools help people stay healthy.

Most of our universe is made of matter. We do not see much antimatter in space. This is one of the biggest mysteries in physics. Scientists call the study of this imbalance baryogenesis. We do not know why there is more matter than antimatter. Some people once thought there might be whole antigalaxies out there.

16slicePETCT
16slicePETCT

Now, NASA looks for signs of antimatter in deep space. They watch for gamma rays from colliding superclusters. Finding the answer would explain how our universe began.

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