High-speed electrons prove Einstein was right about the speed of light

By Leah Crane
If you are driving a car and match your speed to the vehicle in front, it will appear to slow down, relative to you. Albert Einstein said the same isn’t true of the photons emerging from your car headlights, however – they will always travel at light-speed.
This central tenet of Einstein’s theory of special relativity – that the speed of light does not change because of the speed of the observer – has now been proved right more precisely than ever before.
Vahe Gurzadyan and Amur Margaryan at Yerevan State University in Armenia used data from two experiments at the European Synchrotron Radiation Facility in France to look for signs of a changing speed of light.
The rst experiment measured the speed of a photon in a moving reference frame. A high powered laser is æred at a beam of fast-moving electrons, bouncing off into a detector that measured their momentum to ænd the speed of light from the electrons’ frame of reference – the equivalent of measuring the photons from your moving car’s headlights.


Updated: 11/15/18