Harvard University engineers have made the world’s smallest radio receiver, built out of an assembly of atomic-scale defects in pink diamonds. The tiny radio, whose building blocks are the size of two atoms, can withstand extremely harsh environments and is biocompatible, so it could work anywhere from a probe in space to a pacemaker in a human heart. Since it's a radio, it can play whatever you want to send its way, including Christmas music. The radio is extremely resilient, thanks to the inherent strength of diamond. The team successfully played music at about 660 degrees Fahrenheit.