Since glass is a solid, how can we see through it? Why can't we see through wood?
We can see through glass because light passes through it. Our eyes only see objects chairs, the phone, your computer, or even tinted glass by processing light waves reflected off the object or absorbed by it.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.