Is the universe fully determined, eg were a supreme being or a very powerful being to copy the universe in its early state create a parallel universe that would unfold in the exact same way as our universe, down to the everyday decisions made by every human being who lives or ever lived ? In the 19th century the answer would have been yes, Pierre-Simon Laplace of the Laplace transform fame would say yes: But in the 20th century the scientific discovery of Quantum Mechanism sheds strong doubts about the former statement. QM in its very nature is probabilistic. Particles can come into being at random, and the quantum process is part of our thought process. Of course, nothing is fully understood on this front. The probabilistic nature of QM might be an approximation and there might exist some hidden variables that would make QM deterministic, but this is not the opinion of most scientists today. The current thinking is that a universe that started out just like ours would not unfold in the exact same way and there might be differences. Does this means that the universe is not deterministic. Well, scientists today can be less confident of this than during Laplace's time.