Figure 2. The factor γ as function of the speed v / c for a particle of the elementary charge e in sub- and superluminal conditions. The arrow on the abscissa marks the speed limits touching the light-barrier

From

The Mysterious Constant Alpha (α) in Quantumphysics

T. G.M. Gerlitz

International Journal of Physics. 2022, 10(1), 59-63 doi:10.12691/ijp-10-1-4