I recently stumbled upon the definition of a Relativistic particle
:
A relativistic particle is a particle which moves with a relativistic speed; that is, a speed comparable to the speed of light.
However I remember from the university courses that the electrons of an atom are described in term of probability density (cloud).
So my question is that how can we link the concept of trajectory
to the one of electron cloud
. It seems to me that those concepts are contradictory.