Updated: Dec 5, 2020
How fast does light travel? Well, you might say the speed of light, but physicists have only ever measured the two-way speed of light, where light heads out and bounces back. But we have never measured the one-way speed of light and it could be between half "the speed of light" and infinity.
This is not a new insight! Einstein realised it in 1905! So why do so few scientists and students know this?