Matter vs antimatter

Nebulae in space

The Big Bang model suggests equal quantities of matter and antimatter should have formed, but the antimatter is nowhere to be seen out in space. A new experiment gives clues as to why matter has come to dominate.

  • Big Bang model suggests equal amounts of matter and antimatter
  • But only matter is seen widespread throughout the universe
  • New experiment gives clues as to why matter is dominant

A large collaboration of physicists working at the Fermilab Tevatron particle collider in the USA has found evidence for a possible explanation for the prevalence of matter over antimatter in the universe.

They found that smashing protons together in their experiment produced short-lived particles called “B mesons” that almost immediately broke down into debris that included slightly more matter than antimatter.

When particles of matter and antimatter collide, they annihilate each other and release energy. If there is slightly more matter to begin with, then all the antimatter will be annihilated, leaving a small excess of matter.

This sort of matter/antimatter asymmetry accounts for the fact that just about all the material in the universe is made of the normal matter we’re familiar with.

The Fermilab Tevatron

The Fermilab Tevatron (circular feature in background) is used to smash atomic particles together at high speed.

The Big Bang model suggests that equal amounts of matter and antimatter should have been formed, but the antimatter seems to have disappeared—everything in the universe seems to be made of normal matter. Why?

Physicists have long known about processes described by current physics theory that would produce tiny excesses of matter, but the amounts the theories predict are far smaller than necessary to create the universe we observe.

The Tevatron experiments suggest that we are on the verge of accounting for the quantities of matter that exist today.

But the truly exciting implication is that the experiment implies that there is new physics, beyond the widely accepted Standard Model, that must be at work.

If that’s the case, major scientific developments lie ahead.

The results emerge from a complicated and challenging analysis, and have yet to be confirmed by other experiments.

If the matter/antimatter imbalance holds up under the scrutiny of researchers at the Large Hadron Collider in Europe and competing research groups at Fermilab, it will likely stand as one of the most significant milestones in high-energy physics, according to Roy Briere of Carnegie Mellon University in Pittsburgh.

The results have been published in the journals Physical Review Letters and Physical Review D.

Adapted from information issued by APS / NASA / ESA / Orsola De Marco (Macquarie University).

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