Light waves always travel at the speed of light in a vacuum, which is approximately 186,282 miles per second (299,792,458 meters per second).

Here's the catch:

* Light slows down when it passes through a medium like water, glass, or air. This is because the light interacts with the atoms of the medium, which slows it down.

* The speed of light in a vacuum is a fundamental constant of the universe. It's the fastest speed at which anything can travel.

So, to answer your question directly: light waves always travel at the speed of light in a vacuum.