renormalisaatioon

Renormalisaatioon is a technique used in quantum field theory to handle infinities that arise in calculations. These infinities appear when considering the interactions of elementary particles at very small distances or high energies. Specifically, when performing perturbation theory calculations, loop diagrams often lead to divergent integrals, meaning they produce infinite results. Renormalisaatioon provides a systematic way to absorb these infinities into a redefinition of physical quantities like mass and charge.

The core idea is that the parameters we measure in experiments, such as the mass of an electron or the strength of electromagnetic interaction, are not the "bare" parameters that appear in the fundamental equations of the theory. Instead, they are "renormalized" by the effects of virtual particles that are constantly popping in and out of existence. Renormalisaatioon effectively accounts for these virtual particle contributions.

The process involves introducing a cutoff, a limit on the energy or momentum scale, to make the integrals finite. Then, the infinities that appear as the cutoff is removed are absorbed into a redefinition of the fundamental constants of the theory. This process results in a theory that is finite and predictive, meaning it can be used to make accurate predictions that can be compared with experimental results. Renormalisaatioon is a crucial tool that has enabled the success of quantum electrodynamics and other quantum field theories.