No joke. It's a widely known and tested experiment. Might be room for some reservations about how to interpret the results, but the evidence is clear, there is no room for free will, and choice has no effect on reality
I came across an experiment in a lab at university, bunch of lasers and mirrors on a table used to prove the future is deterministic, there is no free will, choice is an illusion, bound by fate, literally - was belief, is now fact