Q: Which came first, dawn or dusk?
A: A circle has no beginning.
Q: In an instant, how fast is an arrow?
A: It flies at every speed.
Q: Why is night dark?
A: Because the universe is expanding.
Q: What is the speed of darkness?
A: The same as the speed of light.
Q: But what is the speed of light?
A: The same for everybody.
Q: Is light a wave or a particle?
A: That depends on how you look at it.
Q: How did the cat cross the lawn?
A: By a sum over every path.
Q: When did the wind shift?
A: When a butterfly flapped its wings.
Q: Why did the apple fall?
A: Because space-time is curved.
Q: Why don’t I fall through the floor?
A: Because electrons have spin one-half.
Q: Why doesn’t the Earth stop turning?
A: Because to physics, all directions are alike.
Q: Why doesn’t the sun go out?
A: Because to physics, all times are alike.
Q: Why doesn’t the moon fall from the sky?
A: Because to physics, all places are alike.
Q: Why don’t rivers run backwards?
A: Because you can’t unscramble an egg.
Q: Then why can’t you unscramble an egg?
A: Because rivers don’t run backwards.
Q: Is there intelligent life in the universe?
A: How would you know?