How Does This Candle Suck Water Up Into a Glass?

Photo: Rhett Allain

It’s a classic demo and one that you can try yourself. You light a candle and put it in some water (I used blue dye in my water). Next, cover the candle with a glass. As the flame burns out, the water gets “sucked” up into the glass. It’s pretty cool.

Let me start off with the “sucked” part. No, the water isn’t actually sucked up. Actually, the pressure inside the glass is reduced…