Researchers working at Harvard University claim they’ve just discovered something that could upend the world of physics, but many other scientists are skeptical of the claim. The scientists claim they’ve figured out how to produce metallic hydrogen, something that is seen as the “holy grail” of high-pressure physics, but they face an uphill battle convincing everyone that the research is sound.

Hydrogen is the simplest atom in the universe with a single proton and a single electron, and although it exists almost exclusively as a gas, like every element it could theoretically be turned into a liquid and solid state. But to turn it into a solid metal, it would take some incredible intense pressure, and scientists have spent decades trying unsuccessfully figure out a way to do that.

The researchers at Harvard claimed in a recent paper they figured it out, but scientists said in another paper that they doubted the claims and that it was likely just another failed attempt in this area among many others, according to a report from Nature.

Harvard claims in a statement: “The material – atomic metallic hydrogen – was created by Thomas D. Cabot Professor of the Natural Sciences Isaac Silvera and post-doctoral fellow Ranga Dias. In addition to helping scientists answer fundamental questions about the nature of matter, the material is theorized to have a wide range of applications, including as a room-temperature superconductor. The creation of the rare material is described in a January 26 paper published in Science.”