Are You Just a Brain in a Vat?How can you be sure your reality isn't a simulation?

From the show

Living Thought Experiments

This thought experiment challenges our certainty about the external world. It suggests your brain could be in a jar, fed all your experiences by a supercomputer. Because a simulated reality would feel identical to a real one, it raises a profound question: if we can't prove we aren't living in a simulation, what does it truly mean to know anything?