There are some generous experts who are willing to befriend the general public~~brilliant professionals who have a gift for bringing the amateur into their world, making the complex understandable and painting such informative word pictures that the visitor into their expertise leaves with a slightly elevated IQ.

Neil deGrasse Tyson is one of these.  His book Death by Black Hole and other cosmic quandries (W. W. Norton & Company, 2007) has this bit about the speed of light in a vacuum.

Including the space shuttle and Superman, a few things  in life travel faster than a speeding bullet.  But nothing moves faster that the speed of light in a vacuum.  Nothing.

Because light has a speed, astrophysicists know that looking out in space is the same as looking back in time….

These concepts are not exclusively cosmic.  True, when you flick on a wall switch, you don’t have to wait around for the light to reach the floor.  Some morning while you’re eating breakfast and you need something new to think about, though, you might want to ponder the fact that you see your kids across the table not as they are but as they once were, about three nanoseconds ago.  Doesn’t sound like much, but stick the kids in the nearby Andromeda galaxy, and by the time you see them spoon their Cheerios they will have aged more than 2 million years.