In the right light, everything casts a shadow—even an atom. A large object creates a shadow by physically blocking the light flying past it, and even a miniscule atom or ion can prevent photons with specific wavelengths from reaching their destinations.
Australian researchers from Griffith University captured a relatively large ytterbium atom in an ion trap, and then hit it with light of a wavelength the ytterbium could absorb. When the light reached the detector, the missing photons that the atom had gobbled up left this negative space: the shadow of a single atom, less than a millionth of a meter in length.
Image courtesy of Kielpinski group, Griffith University / Nature Communications