Philosopher Nick Bostrom proposed the simulation hypothesis in 2003, and the belief has only snowballed since then. Most notably, Elon Musk and astrophysicist Neil deGrasse Tyson have jumped on the nothing-we-know-is-real bandwagon. Tyson hosted the 2016 Isaac Asimov Memorial Debate at the American Museum of Natural History, which addressed this question head-on: Is the universe a simulation? At the event, Tyson was joined by panelists Lisa Randall, a theoretical physicist at Harvard; Max Tegmark, a cosmologist at MIT; David Chalmers, a professor of philosophy at NYU; Zohreh Davoudi, a theoretical physicist at MIT; and James Gates, a theoretical physicist at the University of Maryland.
The opinions on the simulation hypothesis varied (Chalmers had a real mind-boggler: "We're not going to get conclusive proof that we're not in a simulation, because any proof would be simulated."). Tyson himself said, "I think the likelihood may be very high. [...] it is easy for me to imagine that everything in our lives is just a creation of some other entity for their entertainment." But whether or not everyone is in agreement about the matter, the concept is legitimate enough for the top minds in theoretical physics to meet on and parse out. (Here's the whole transcript from the panel if you're interested in a long read, or check out watch the two-hour panel discussion in the video below.)