| UPDATED: 10:47, Thu, Feb 18, 2021 Link copied Sign up for FREE for the biggest new releases, reviews and tech hacks SUBSCRIBE Invalid email When you subscribe we will use the information you provide to send you these newsletters. Sometimes they'll include recommendations for other related newsletters or services we offer. Our Privacy Notice explains more about how we use your data, and your rights. You can unsubscribe at any time. Providing a description of gravity as a geometric property of space and time, or spacetime, Einstein’s theory has important astrophysical implications as it alludes to the existence of black holes – cosmic phenomena where nothing, not even light, can escape. According to the “no-hair theorem” of his equations, black holes have three characteristics — mass, spin and charge – so if those three values are the same in two black holes, it is impossible to tell them apart. But scientists have started to question this.