Imagine supercomputers that think with light instead of electricity. That s the breakthrough two European research teams have ...

Scientists have apparently broken the universe's speed limit. For generations, physicists believed there is nothing faster than light moving through a vacuum -- a speed of 186,000 miles per second.

For example, light slows down when passing through glass or water. Padgett and his team wondered if there were fundamental factors that could change the speed of light in a vacuum.

For example, in water, light travels at about three-fourths its vacuum speed; in glass, it's around two-thirds. The ratio between the speed of light in a vacuum and its speed in a material is ...

When light travels through glass or water, it’s slowed down. But scientists thought that, when it flashes through a vacuum, it's kept to the unvarying speed of 299,792,458 meters per second .

That means that when light is in glass, it travels with a speed that's only 0.667 times as fast as in a vacuum, with a value of 1.97 x 10 8 m/s. How about some other materials?

All massive particles could only approach it, but would never reach it. The speed of light, ... it's just ~225,000,000 m/s in water and just 197,000,000 m/s in crown glass. This slow speed, ...

Particles, like these electrons, that surpass the speed of light in water, or some other medium such as glass, create a shock wave similar to the shock wave from a sonic boom.

In 1676, by studying the motion of Jupiter's moon Io, Danish astronomer Ole Rømer calculated that light travels at a finite speed. Two years later, building on data gathered by Rømer, Dutch ...