Some of the world's richest and most powerful people are convinced that we are living in a computer simulation. And now they're trying to do something about it. At least two of Silicon Valley's tech billionaires are pouring money into efforts to break humans out of the simulation that they believe that [we are] living in, according to a new report. Philosophers have long been concerned about how we can know that our world isn't just a very believable simulation of a real one. But concern about that has become ever more active in recent years, as computers and artificial intelligence have advanced. "Many people in Silicon Valley have become obsessed with the simulation hypothesis, the argument that what we experience as reality is in fact fabricated in a computer," writes The New Yorker's Tad Friend. "Two tech billionaires have gone so far as to secretly engage scientists to work on breaking us out of the simulation." The detail came from a New Yorker profile of Sam Altman, who runs Y Combinator which helps develop tech companies. A number of prominent tech billionaires have discussed the idea of the simulation - including Elon Musk, who has used his fortune to fund potentially odd efforts in the past. If we aren't actually living through a simulation, Mr Musk said, then all human life is probably about to come to an end and so we should hope that we are living in one. "Otherwise, if civilisation stops advancing, then that may be due to some calamitous event that stops civilisation," he said.