LED lighting, solar power and lasers are just some of the electronics revolutionised by two obscure chemical elements - gallium and indium. Laurence Knight hears from Mike Simpson of Philips why we will only need to replace our lightbulbs once every two decades, and travels to Sheffield University where research centre head Jon Heffernan explains what on earth III-V materials are and why making an LED is like baking a pizza. Meanwhile chemistry stalwart Prof Andrea Sella of UCL demonstrates these two metals' surprisingly buttery melt-in-the-mouth properties. (Photo: Times Square New Year's Eve ball, Credit: Jeff Zelevansky/Getty Images)