Baryogenisis: how matter came to be

One of the greatest mysteries of the Universe, apart from its reason for existing, is the question “How?” : how did we come to be, how did it all start… These existential questions can throw us into Nihilistic thought, but they can also make us look further, deeper, in an attempt to find meaning in this random Universe. A big question is “How did matter come into existence?” .

The Standard Model

First of all, what is matter? The matter that we observe is known as baryonic matter, matter formed by known particles: protons and neutrons. Observations have shown that only 5% of the Universe is baryonic matter, the rest being dark matter and dark energy, whose existence and composition had not yet been determined. The Standard Model is a physical model which classifies elementary particles and explains interactions between matter (except for gravity). All matter particles have an antimatter particle. Antimatter particles are particles that have the same mass but with other properties such as electric charge being opposite. When antimatter and matter interact together, they annihilate, i.e. destroy each other, releasing their energy in the form of photons.

Baryon Asymmetry

The Standard Model predicts that matter and antimatter should have been created in symmetric amounts at the beginning of the Universe; however, as can be seen, matter exists, and so there must have been a moment where a baryon asymmetry appeared, i.e. there were more matter particles than antimatter particles, or else all matter would have annihilated and we wouldn’t be here. This process of the asymmetry appearing is known as baryogenesis, as it is the “creation” in some way of the observable matter in the Universe.

There is not an equal amount of baryonic matter as antibaryonic matter, but how did this happen? This phenomenon is not fully explained by the Standard Model, and we do not know what would have caused this asymmetry in the early Universe in the first place. It is one of the limitations and pending questions in particle physics.

LHCb

Observations show that matter and antimatter do not follow physical laws which imply symmetry. New experiments are being theorised and conducted to find the cause of this baryon asymmetry which so intrigues scientists. The LHCb experiment (Large Hadron Collider beauty experiment) is one such experiment, which seeks to find how this asymmetry happened in the early stages of the Universe. It is formed of a detector, and some other discoveries, such as the accidental discovery of the “pentaquark” have been made, but not yet anything conclusive regarding baryon asymmetry. You can read more about this experiment on their webpage.

Physics is a vast field of study, and there are many questions which are unanswered. The Universe is fascinating, but we have only scratched the surface of it. The matter that we see is such a small fraction of it, and even yet we have not quite understood all the physics behind it. Someday in the future, new discoveries will finally answer these questions, but new questions will appear, enticing a new generation of curious physicists to investigate and look further by standing on the shoulders of giants, as Newton said.

 

Editor: Maria ‘Stefi’ Ticsa

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