Physics
Mass Increase (Relativistic Mass)
Quick fact
A particle accelerated to 99.9999% of light speed in the Large Hadron Collider has a relativistic mass more than 7,000 times its rest mass.
Why this is interesting
Imagine pushing a sled: the harder you push, the faster it goes. But what if, as it gained speed, it also became heavier—so heavy that no amount of pushing could make it reach a certain speed?