Antimatter
Written by John Carl Villanueva
If matter is a collection of particles, then antimatter is a collection of antiparticles. Let's have an example using a very simple atom, say, hydrogen. A neutral hydrogen atom is composed of one proton and one electron. Therefore, the antimatter counterpart of this atom, which we can call an antihydrogen, would be composed of an antiproton and an antielectron.
An antiproton is a proton with a negative charge while an antielectron, which is more commonly known as a positron, is an electron with a positive charge. Just a little reminder: an antiproton and an antielectron both have exactly the same mass as a proton and an electron respectively. The only difference are their charges.
Just as a particle and an antiparticle will annihilate each other when they make contact, so will a matter and an antimatter. Among the greatest mysteries of the Universe is the asymmetry of matter and antimatter. Nature is known to favor symmetry. That is why many scientists find it strange to find more matter than antimatter. Could it be possible that a substantial amount of antimatter is stashed somewhere in the far-flung areas of the Universe?
Although antimatter is not readily found in nature, scientists have long been playing with it by smashing subatomic particles together in huge particle accelerators like those in Fermilab and CERN. The purpose of smashing particles to produce antiparticles and eventually smashing them with particles as well, is to simulate the conditions during the Big Bang and subsequently the origins of the Universe.
As with a number of discoveries in Physics, the discovery of the antiparticle was a result of trying to make heads or tails out of a mathematical equation that made perfect sense on paper but never observed in nature. In trying to bring the principles of quantum theory and special relativity together through what is now known as the Dirac equation, a theoretical physicist by the name of Paul Dirac proposed the presence of antimatter.
The existence of antimatter was confirmed a few years later by Carl Anderson while studying cosmic particles in a cloud chamber and observing a particle which had the same signature as an electron except that it was positively charged, hence the name positron.
Today, antimatter is considered the answer to the limitations of conventional fuel. When matter and antimatter collide and annihilate one another, their masses are totally converted into energy; a very gargantuan amount according to Einstein's E=mc2.
You can read more about antimatter here in Universe Today. There are new differences between matter and antimatter that you might want to know about. We've also written about a possible reason why there's more matter than antimatter in the Universe.
There's more about it at NASA. Here are a couple of sources there:
- What's the Matter with Antimatter?
- Reaching for the stars – Scientists examine using antimatter and fusion to propel future spacecraft
Here are two episodes at Astronomy Cast that you might want to check out as well:
Filed under: Astronomy
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