59,482 views
472 likes
Electrons have no known physical size. They behave like point-like particles with no surface, no volume, and no internal structure. So how can physicists collide two electrons? In this video, we’ll explore what a particle collision really means, how quantum fields and virtual photons make it possible, and how powerful accelerators have tested the electron down to incredibly small scales.
0:00 Introduction: how do you collide something with no size
1:08 What a pointlike particle actually means
2:47 The classical electron radius and early ideas
4:07 The problem of infinite self energy
5:13 Quantum electrodynamics and renormalization
6:06 How scattering experiments measure size
7:56 LEP collider results and the limit on electron size
9:01 The magnetic moment and the Penning trap
10:47 The fine structure constant discrepancy
11:58 What a collision really is: cross sections and virtual photons
14:47 The wave nature of the electron and how accelerators work
19:54 Fields instead of things and the final thoughts
