Physics Colloquium - Peter Maták (24.6.2021)
Thursday 24.6.2021 at 16:00, Lecture room C
By: František Herman
On the Origin of Matter in the Universe
The origin of matter-antimatter asymmetry of the universe belongs to the most interesting open questions in contemporary astroparticle physics. After a brief introduction to the essential ingredients of cosmology, the necessary conditions for the matter asymmetry generation will be explained. When speaking of matter in the universe, we think of the staff made of particles. What are the particles (in the modern physics sense), and why the language based on particle description is always just an approximation of physical reality? To explain the origin of matter, the particles are often considered classical point-like objects revealing their quantum nature in the interactions only when coming close to each other. The overabundance of matter over antimatter, or particles over antiparticles, which is a key to the existence of the universe as we observe it, can then be explained in terms of the difference in their interactions. Such difference is deeply connected to temporal asymmetry occurring in particles’ decays and scatterings. The temporal asymmetry, or the arrow of time, may seem to be familiar from everyday life. Watching a movie where a cup falls on the floor and breaks into many glass pieces, we can easily decide whether the movie is shown in a forward or backward direction. A note often follows this typical example that particles’ interactions use to be time-symmetric. That this does not have to be the case, and what role it plays in the matters’ origin will be the topic of this lecture.