Maximum Entropy and Acausal Processes: Astrophysical Applications and Challenges

Abstract

In Newtonian physics, if we know the state of the world at some moment of time, then we can precisely predict the state of the world at all future times. In this sense, Newtonian physics is deterministic. In modern physics (starting with quantum mechanics), theories are usually non-deterministic in the sense that even if we know exactly the initial state of the world, we cannot uniquely predict the future state of the world. In quantum mechanics (and in most modern quantum-based physical theories), the best we can get is probabilities of different future states. In this sense, in the majority of modern physical theories, uncertainty is of statistical nature.\rLately, a new area of acausal (causality violating) processes has entered mainstream physics. This area has important astrophysical applications. It can be shown that if an acausal process is possible, then some events will take place, whose probability is normally extremely low to prevent this acausal influence from happening.\rAccording to statistical physics, the probability of a macro-state monotonically depends on its entropy, and therefore, the state most probable to occur is the one with the maximal entropy. In this paper, we use MaxEnt to show how the possibility of acausal processes explains the isotropy of the universe and the over-abundance of particles over anti-particles. We will also describe the open MaxEnt problems arising from acausal applications and show that the possibility of acausal processes leads to a field of physics where probabilities are non-frequential.