Antimatter

Definition

Antimatter is a type of matter composed of antiparticles, which have the same mass as particles of ordinary matter but opposite charges. When antimatter and matter meet, they annihilate each other, releasing energy.

5 Must Know Facts For Your Next Test

1. Antimatter particles have opposite electric charges compared to their corresponding matter particles.
2. The collision between matter and antimatter results in annihilation, converting their mass into energy according to E=mc².
3. Antimatter was first predicted by Paul Dirac in 1928 and the positron, an antielectron, was discovered in 1932 by Carl Anderson.
4. In the early universe after the Big Bang, nearly equal amounts of matter and antimatter were created.
5. The scarcity of naturally occurring antimatter in the universe remains one of the unsolved questions in cosmology.

Review Questions

• What happens when a particle of matter encounters a particle of antimatter?
• Who first predicted the existence of antimatter and what is an example of an antiparticle?
• Why is the imbalance between matter and antimatter significant in understanding the early universe?

Related terms

Relativity: A theory formulated by Albert Einstein that describes how space and time are interconnected and how objects move within them.

Big Bang: The scientific theory that explains the origin of the universe as an expansion from a hot, dense state about 13.8 billion years ago.

Positron: The antiparticle or antimatter counterpart of the electron with a positive charge.