Why does matter and antimatter annihilate

So far, physicists have not been able to identify the exact mechanism that would produce this apparent "asymmetry," or difference, between matter and antimatter to explain why all the matter wasn't also destroyed. Is there an anti-universe? What would it look like? You will need RealPlayer in order to view this video.

Today, antimatter appears to exist primarily in cosmic rays -- extraterrestrial high-energy particles that form new particles as they penetrate the earth's atmosphere. And it appears in accelerators like CERN's, where scientists create high-energy collisions to produce particles and their antiparticles. Physicists study the properties and behavior of manufactured antiparticles, and the antimatter they form when they combine, hoping to find clues to this asymmetry mechanism. Most scientists believe that a subtle difference in the way matter and antimatter interact with the forces of nature may account for a universe that prefers matter, but they haven't been able to definitely confirm that difference in experiments.

Theories suggest that even if equal amounts of matter and antimatter were created with the Big Bang, disparities in their physical properties -- such as decay rate or life span -- might favor a matter-filled world. In , Russian theoretical physicist Andrei Sakharov postulated several rather complex conditions necessary for the prevalence of matter.

One required something called "charge-parity" violation, which is an example of a kind of asymmetry between particles and their antiparticles that describes the way they decay.

But more importantly, it will outline further tests to deepen the understanding following our finding—with a number of such tests already ongoing. Over the coming decade, the upgraded LHCb experiment will boost the sensitivity for these kinds of measurements. This will be complemented by the Japan-based Belle II experiment , which is just starting to operate.

These are exciting prospects for research into matter-antimatter asymmetry. Antimatter is also at the heart of a number of other experiments. And a number of current and future experiments will tackle the question of whether there is antimatter-matter asymmetry among neutrinos.

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Panofsky Prize in Experimental Particle Physics. The question on Stone's mind involves the equal-but-opposite nature of matter and antimatter.

Obviously, that didn't happen," he says in a whiff of understatement. Thus, Stone and his LHCb colleagues have been searching for subtle differences in matter and antimatter to understand why matter is so prevalent. The answer may lie at CERN, where scientists create antimatter by smashing protons together in the Large Hadron Collider LHC , the world's biggest, most powerful particular accelerator.

The more energy the LHC produces, the more massive are the particles--and antiparticles--formed during collision.