For nearly 100 years, scientists have dreamed of turning the lightest of all the elements, hydrogen, into a metal. Now, in a stunning act of modern-day alchemy, scientists at Harvard University have finally succeeded in creating a tiny amount of [this] material. Metallic hydrogen could theoretically revolutionise technology, enabling the creation of super-fast computers, high-speed levitating trains and ultra-efficient vehicles and dramatically improving almost anything involving electricity. But the prospect of this bright future could be at risk if the scientists' next step - to establish whether the metal is stable at normal pressures and temperatures - fails to go as hoped. Professor Isaac Silvera, who made the breakthrough with Dr Ranga Dias, said: "This is the holy grail of high-pressure physics. "It's the first-ever sample of metallic hydrogen on Earth, so when you're looking at it, you're looking at something that's never existed before." At the moment the tiny piece of metal can only be seen through two diamonds that were used to crush liquid hydrogen at a temperature far below freezing. The amount of pressure needed was immense - more than is found at the centre of the Earth. Sometime in the next few weeks, the researchers plan to carefully ease the pressure. According to one theory, metallic hydrogen will be stable at room temperature. If this is true, then [it] could ... transform humanity's efforts to explore our solar system by providing a form of rocket fuel nearly four times more powerful than the best available today.