Can light travel at less than the speed of light?

A2A Yes! The visible portion of the Electromagnetic (EM) wave spectra is generally referred as “Light”. EM waves move in the vacuum or no medium with a speed of 3*10^8 m/s (c). read more

Light can never move at anything else than the speed of light. Speed of light can be slowed slightly as it travels through materials such as water or glass, it has generally been thought impossible for particles of light, known as photons, to be slowed as they travel through free space, unimpeded by interactions with any materials. read more

But to keep the speed of light constant at all times and for all observers, in special relativity, space and time become stretchy and variable. Time is not absolute, for example. A moving clock ticks more slowly than a stationary one. Travel at the speed of light and, theoretically, the clock would stop altogether. read more

The speed of light in a vacuum is 186,282 miles per second (299,792 kilometers per second), and in theory nothing can travel faster than light. In miles per hour, light speed is, well, a lot: about 670,616,629 mph. read more