I have seen in the past (during my voyages in the crazy recesses of the Internet) certain arguments about why reincarnation is just common sense or based on physics. I might as well write down why this isn’t the case.
I haven’t read any formal studies or well-written articles on this, but the argument as I have seen it is this:
1. Physics tells us energy is never lost. (The Law of Conservation of Energy.)
2. Therefore, when a person dies, their soul orhas to go somewhere.
3. Reincarnation is a good explanation where.
4. Therefore, reincarnation is probable based on what we know.
Rather than an argument based on physics, this is complete nonsense. The reason is simple: When physics speaks of “energy”, it means something specific. Energy is the ability to cause physical actions, roughly speaking. It exists in certain forms — heat, kinetic (movement), chemical energy and so on — which can change into each other, or even into matter in extreme cases, but not disappear.
Well, what’s the problem? Don’t our souls cause our bodies to move? Not in the sense of being physical energy. You can explain everything that goes on in a human body without postulating an extra energy source that is the soul. Everything works by physical processes. It’s in explaining conscious experience that we need to speak of something like the soul, and even then science suggests rather that it’s a supervenient property of the organisation of the physical matter rather than something separate. And similarly, when life ceases, there is no mysterious vanishing of energy from the body or anywhere else, any more than we have to wonder where the movement “goes” when a ball stops rolling.
What the “argument” does is a simple, completely unjustified leap of imagination: Taking the Law of Conservation of Energy, it then decides to call something (rather vague) energy and then apply the law to that. But the law is a law of physics, and it involves a definition of just what it means by energy. The soul or life energy isn’t part of that definition, so the law doesn’t apply to it. Indeed, if there were an unknown type of energy (and it would be, since science doesn’t recognise such a type) that can act like known types of physical energy, it would appear at the moment that the Law of Conservation of Energy is not true, since the “soul energy” would add mysterious effects that seem to come out of nowhere. But there isn’t, and the reasons given for thinking there is are nonexistent. And even if there were reasons to think there is some special energy totally outside what has actually been observed, it would not automatically be included in the law of physics, which is based on what has been observed, just because someone happened to decide to call it “energy”.
In sum, the argument is worthless because it’s based on equivocation, using the same word in different senses in different part of the argument. It makes as much sense as Terry Pratchett‘s tongue-in-cheek fictional proof for the notion that libraries distort space according to the Theory of Relativity: knowledge = power = energy = matter = mass, mass bends space, therefore a library is “just a genteel black hole that knows how to read” (may or may not be an exact quote from somewhere in the Discworld series, I’m not looking at a source as I write this). Don’t think to yourself it makes at least a little more sense than that. As an application of the laws of physics, it makes precisely as little sense as that. It has nothing to do with what physics says, just the misuse of words and concepts.
Obviously, the same kind of argument can be applied just as unsuccessfully to the immortality of the soul in general.
Some further thoughts.
First, if there was a soul energy, it more likely would be conserved, or at least conservation would apply after it has had an effect on physical things, since then it would presumably be transformed into other types of energy. This does nothing to change the point that we have no grounds to suppose such a thing in the first place.
Secondly: From soul being “energy”, you get “reincarnation”? Really? If it were energy, capacity to make things move and stuff, you might get some kind of Buddhist style no-self alternative where a person isn’t reborn so much as their karma or something passes on. (Karma is, or has been treated, as another quasi-sensible concept like what is discussed here: I’ve seen people say that karma is “just causality”, but apparently implying that somehow this “causality” acts in a morally just way even when there is no external reason to expect that to happen.) Your personality is a complex structure; if all that passes on is “energy” in some sense that resembles the real concept at all, you’re not going to have this “Hypnosis revealed that I had been the Queen of Sheba” kind of reincarnation. (As an aside, hypnosis is known to be able to give people “memories” of just about anything, not just things that have happened.) You’d have something more analogous to the idea of the physical matter in your body being recycled to make dirt and stuff, your personality just destroyed. So, your formless psychic energy could be transferred to some new person the same way as some flower might appropriate some atoms left behind from your body. Of course, all of this would only apply if there was some soul energy in the first place.