If some of your ping pong balls are dented or crushed, don't worry — they're still usable. To restore their shape, immerse the balls in a pot of hot water or pour boiling water over them.

An curved arrow pointing right. NASA's Scott Kelly turned a ball of water and two hydrophobic paddles into an out of this world game of ping pong on the International Space Station. Story by Tony ...

and a ping-pong ball. You can see the video below. Imagine for a moment heating a tank of water as an example. The simple approach would be to turn on the heater and when the water reaches the ...