Annihilation Theory

e+ + e- → γ

(A positron plus and electron results in a gamma ray)

Equations like these show the fundamental properties of all interactions. Here, the resultant is a gamma ray, which indicates that (considering that gamma particles travel at the speed of light) we should supposedly be living in a universe filled with light. There should be no preference for matter yet the omnipresent solid mass that surrounds us obviously denotes something missing in the above equation. Sakharov's conditions describe what would have to happen in order for this imbalance to occur.

Sakharov himself was a prominent Soviet Nuclear physicist. He is renown not only for his contribution to science but also for numerous humanitarian works in reforming the Soviet Union. Eight years after he thought of the three conditions, in 1975, he was awarded the Nobel Peace Prize in recognition for his campaigns for human rights. His work in cosmology has also been widely recognised and his proposal for the conditions necessary to create the antimatter imbalance have proved a substantial contribution to this area of science.

The first of his conditions is a bold proposal. It has not been proven in any physical experiments, but Sakharov proposed that conservation laws do not forbid reactions that change the balance between particles and antiparticles. Conservation laws state that the portion of the universe chosen for analysis does not change as the universe evolves, and these laws have not been known to have exceptions.

To counter this Sakharov's second condition points out that the laws of physics must be slightly different for matter and antimatter. Unlike his first proposal, the second has some solid evidence behind it. In 1964 four physicists Christenson, Cronin, Fitch and Turlay discovered at Brookhaven that long-lived Kaon's can decay into two pions. This means that the weak force (its most familiar effect being in beta decay) does not act equally on quarks and antiquarks (quarks and antiquarks being an example of matter and antimatter).  This second condition supports the first and could possibly be the only evidence for it. A slight difference in the ratio of matter and antimatter could evolve into the huge unequal portions of both that are present today.

This preference for matter is also evident in the third condition. Sakharov's final condition argues that the reactions between matter, antimatter and radiation started occurring at different rates. This would have theoretically occurred quite early in the universes history. To make this plausible there must have been some disruption to the thermal equilibrium. A bubble that, in theory, was created when the universe was less than 10^-12 (ten to the power of negative twelve) seconds old could have potentially upset the thermal equilibrium. The surface area of this bubble, which was expanding at a rapid rate and its interior was cooled, could have caused disturbance to the thermal equilibrium. Again at the surface of the expanding bubble, some particles bounced off whilst others broke through. It is believed interactions at the bubbles surface made it easier for a quark to brake through rather than an antiquark. Thus leaving a greater amount of quarks within the bubble. This bubble now marks the boundaries of our universe and since we live within it the above theory could further explain the preference for matter in our universe.  

If all of the above theories were proved to be totally factual it would paint a lovely neat picture for physicists to work on. However, the creation of the universe is not that simple. The laws that have been proven to be correct in the past are constantly modified then contradicted by new information. Discoveries such as these are crucial to understanding the topic however such differing interpretations of fact only adds to the complexity of the matter. Take into account Sakharov's first condition for example. If it is true then it alters the current knowledge of conservation laws and this affects our understanding of motion.

Our understanding of this is crucial to progress. We are constantly moving towards solving the antimatter mystery of why there is something rather than nothing. New resources are aiding our discovery, a strong example of this being the Large Hadron Collider (LHC) that was launched in Switzerland last week. The Large Hadron Collider Beauty detector was designed with the intension of showing the slight differences between matter and antimatter by studying a type of particle called the beauty quark. The experiment incorporates sub-detectors that have been positioned very close to the collision point and then cascade one after the other for a distance of 20 metres. Movable tracking detectors are being used to catch the beauty quarks. All of this is very advanced, sophisticated technology. This will inevitably lead to a greater understanding of the universe, which will contribute to physicists developing new theorems to explain the creation of the universe.    

Sakharov's conditions are only three of the infinite possibilities to explain the antimatter mystery. What makes them special is that although those conditions were formed over forty years ago they are still relevant and are applied to modern physics. Nevertheless where there is information there will always be debate and differing interpretations of fact. The only certain way to solving the mysteries of the universe is by using innovation and inquiry, complimented by unbiased interpretation of fact.

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