There’s a theory called the butterfly effect that could explain why things change each time Jake travels back in time. When Isaac Newton came up with the law of motion and universal gravitation in the 1600s, everything seemed predictable within science and the universe. This led to the belief that the future is set and we need to just wait for it to reveal itself. Determinism is the idea that the future is fixed while chaos theory purports that a small deviance could drastically change the outcome. The science of the butterfly effect is that tiny changes in big systems can have complex results.