Antimatter is just like normal matter, except that the particles that make it up are the opposite versions of the particles which make up regular matter. As you should know, everything physical in the universe is made up of atoms, and those atoms are made of protons, neutrons and electrons. These particles have a number of properties (mass, spin, etc) including charge. An electron has negative charge, and the amount of charge is exactly the same for every electron in the universe. But, many decades ago, quantum physicists predicted that there could be another type of electron, identical in every way except for possessing a positive charge. This particle would be called an anti-electron, or a positron. They also figured there must be anti-protons, and anti-matter versions of all particles (Physicists working with powerful particle accelerators later managed to create these anti-particles, proving that they do in fact exist). But if a proton ever comes into contact with its anti-particle, something interesting happens: They totally annihilate each other, leaving behind nothing but the potential energy of their mass according to Einstein’s famous E=mc2 equation. This annihilation is in fact the most potent possible nuclear explosion, and anti-matter bombs are a favourite weapon for science fiction authors.
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