Visit physicist Divine Kumah in his research lab and you’ll find him making what could be described as the world’s tiniest layer cakes. How tiny? Try just a few atoms thick. One hundred thousand of them would barely stack up against a sheet of paper. They’re not for eating, however. He takes his ingredients from the periodic table — oxygen and different metals such as titanium and magnesium — and brings them together in ways not found in nature to create ultra-thin films, one layer of atoms at a time.