Light Speed vs. Wavelength

Do all wavelengths of light moving in a vacumn travel at the same speed?
- John Aho (age 66)
Sequim, WA, USA

Many experiments have been made in the laboratory as well as light-year distances.  None have indicated any differences in the speed of light. One example of an astronomical observation is to look at blue light and red light arriving from a supernova many light-years distant. Both colors arrive at the same time.   This is a very fundamental point.  If, for example, photons had a very small mass then there should be a difference.  

LeeH

(published on 04/21/2008)