In religion, ensoulment is the moment at which a human being gains a soul. In the time of Aristotle, it was widely believed that the human soul entered the forming body at 40 days (male embryos) or 90 days (female embryos), and quickening was an indication of the presence of a soul.

As for backward time travel, it is possible to find solutions in general relativity that allow for it, such as a rotating black hole. Traveling to an arbitrary point in spacetime has very limited support in theoretical physics, and is usually connected only with quantum mechanics or wormholes.

It is already known that quantum mechanics plays a role in the brain, since quantum mechanics determines the shapes and properties of molecules like neurotransmitters and proteins, and these molecules affect how the brain works.

Today some physicists suspect that, whether or not consciousness influences quantum mechanics, it might in fact arise because of it. They think that quantum theory might be needed to fully understand how the brain works.

When a quantum “observer” is watching Quantum mechanics states that particles can also behave as waves. In other words, when under observation, electrons are being “forced” to behave like particles and not like waves. Thus the mere act of observation affects the experimental findings.

In modern physics, the double-slit experiment is a demonstration that light and matter can display characteristics of both classically defined waves and particles; moreover, it displays the fundamentally probabilistic nature of quantum mechanical phenomena.

In the famous double-slit experiment, single particles, such as photons, pass one at a time through a screen containing two slits. Conversely, if neither is checked, a photon will appear to have passed through both slits simultaneously before interfering with itself, acting like a wave.