Antimatter

Every elementary particle in the Universe appears to have a partner particle called its antiparticle that shares many of the same characteristics, but many other characteristics are the opposite of those for the particle. For example, the electron has as its antiparticle the antielectron(also called positron). The electron and the antielectron have exactly the same masses, but they have exactly opposite electrical charges.

The common stuff around us appears to be "matter", but we routinely produce antimatter in small quantities in high energy accelerator experiments. When a matter particle meets its antimatter particle they destroy each other completely (the technical term is "annihilation"), releasing the equivalent of their rest masses in the form of pure energy (according to the Einstein E=mc^2 relation). For example, when an electron meets an antielectron, the two annihilate and produce a burst of light having the energy corresponding to the masses of the two particles.

Because the properties of matter and antimatter parallel each other, we believe that the physics and chemistry of a galaxy made entirely from antimatter would closely parallel that of our our matter galaxy. Thus, is is conceivable that life built on antimatter could have evolved at other places in the Universe, just as life based on matter has evolved here. However, we have no evidence thus far for large concentrations of antimatter anywhere in the Universe. Everything that we see so far seems to be matter. If true, this is something of a mystery, because naively there are reasons from fundamental physics to believe that the Universe should have produced about as much matter as antimatter.

WHY IN NEWS?- Scientists have come closer in understanding why the universe contains more matter than antimatter.Physicists have made important discoveries regarding Bs meson particles — something that may explain why the universe contains more matter than antimatter(Bs meson oscillates between a matter particle and an antimatter particle). But the uncertainties of their results were too high to make any solid conclusions.

Could the Dark Matter be Antimatter?

♤ It is conceivable that the dark matter (or at least part of it) could be antimatter, but there are very strong experimental reasons to doubt this. For example, if the dark matter out there were antimatter, we

would expect it to annihilate with matter whenever it meets up with it, releasing bursts of energy primarily in the form of light. We see no evidence in careful observations for that, which leads most scientists to believe that whatever the dark matter is, it is not antimatter.