Never mind what they say; what do you say?  And why? And how would you go about finding out whether it seems likely that they have a point. And don't you think it interesting that it is an interesting fact?

As for your other question about interesting facts about how things work, go about the house and ask yourself how each thing you see works: an ordinary light bulb; your TV controller (try looking at it through the display of your digital camera whicle you press its buttons; Why did you see what you saw, but not when you look at it directly?) What about a spring mousetrap? What do  you see when you move a calculator with an LED display (Do you still get them?) in the dark, and why? Why will a drop of water skitter calmly  around on the plate of a smoothing iron or a stove when it is very hot, but collapse into a fizz when it has cooled down for a while? Why does it not hurt when you stick your finger into a working electric fan from the front, but it hurts plenty when you do it from behind? (If you try this, you are stupider than anyone in the forum takes you for!)

You want examples? Try looking for non-examples!