Making an invisible, silent, and heat-proof cylinder–for science

"There were many striking examples, and I don't want to turn this into a listicle, so let me discuss just three. Wegener showed how to prevent heat from moving into a volume. Now you might think this is just insulation, but it's not. At the border of an insulated volume, you have a temperature gradient. These gradients then distort the temperature field around the object in a way that, if you were to measure the temperature, you would know there had to be an object in the center.

The metamaterial, which consists of rings of copper (high thermal conductivity) and plastic (low thermal conductivity), guides the energy flow around the hidden volume in such a way that on all sides, the temperature gradient looks exactly as if there was no object between a heat source and the cold sink."