The dream world is not subject to the same laws as the natural world. It is a purely imaginary construct, built entirely from our expectations and imaginations, so absolutely no physical laws are in any way guaranteed to hold for everyone, and even if they did, that would tell us nothing of the laws that govern the natural world. read more
Newton's Laws, as a model, work well, unless you are dealing with things that have very large mass, move at a significant fraction of the speed of light, or are very small in size. At that point, things like relativity, and the uncertainty principal become significant. read more