Computers are widely used in physics and other natural sciences to simulate physical phenomena. Thus, people routinely use computers to model many and different physical systems. In addition, computers have been used to solve difficult problems by simulating successful practices employed by living organism. However, it seems not everything can be simulated, that is, there are phenomena that are characterized as non-computable. Most of them can be simulated by quantum computers but for some even these computers are not adequate. The authors examine why this happens, how it can be solved, and whether the “ultimate” goal of simulating the whole universe is feasible.