With a good estimate for the
speed of light, we can come close to a reasonable estimate of the age of the
universe.
The 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.
(from Death By
Black Hole by Neil deGrasse Tyson)
9½*/10.
The complete review is here.
.
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