Being dense is a good thing! Here's why.
What you are looking at is a thermometer, named after Galileo himself. Density is the trick to the Galilean thermometer and this is how it works. As the temperature of a liquid increases, it's density decreases. Think about it this way. An ice cube is very dense, but as that ice cube is heated, it eventually melts. As it is heated even more, it boils. Finally, it becomes steam. Steam is far less dense than ice, right?
Well, take the principle of density and combine that with the principle of buoyancy, and BINGO, you've got yourself a Galilean thermometer.
As the temperature of the water increases and decreases, the colored liquids held inside each glass bubble rise and fall through the cylinder of water. This is because each has a certain buoyancy and they are reacting to the water's changing density.
You'll notice that each liquid-filled bubble has a tag attached to it, so the tag on the bottom most bubble, tells you the current temperature in the water. And, by extension, the current temperature in the room.
If anybody knows what the magical liquids are inside these bubbles, please post your comments and help me out.
I'm pretty sure one is Sangria and one is PBR, but maybe that's just wishful thinking.