Schrodinger’s wave equation describes how the quantum state of a quantum system changes with time. Everett’s insight was that the observer of a quantum state was as much part of the system as the observed part of the system. Therefore they were “entangled” in the quantum sense and would be covered by a single quantum state equation.
If the observer and the observed are thus entangled, then so must be an observer who observes the quantum state of the observer and the observed. One can then extend this to the whole universe, which leads to the concept of a wave equation or function which describes the whole Universe.
That there is an equation for the universe is not really surprising and indeed, it is not surprising that it could be a quantum wave equation as the quantum world seems to form the basis of the physical, apparently classically described, world that we see.
I base this idea on the fact that everything that we sees appears to be describable in terms of a deterministic equation. It has been argued that such things as “psi phenomena“, but such claims are yet to be conclusively verified, with many putative examples having been discredited.
Some people argue for a soul or mind as an example of a non-physical entity, but any such concept leaves a lot of questions to be asked. A non-physical entity cannot, by definition almost, be measured in any way, and there is difficulty in showing how such a non-physical entity can interact with physical ones, and therefore be noticed or detected.
By definition almost, a physical entity, such a body, is only influenced by physical things. If this were not the case we would see physical entities not following the laws of physics. For example, if it is possible to move an object by mind power or telekinesis, one would see the object disobeying fundamental scientific laws, like Newton’s First Law of Motion.
The mind is a curious example of a physical entity which is often thought of as being non-physical. After all, a mind does not have a physical location, apart from the skull of the person whose mind it is, and it can’t be weighed as such.
The mind however is a pattern, on the brain, made up of the state of trillions of neurones. It is made up of information, and is much like a computer program which is made up of the state of a few billion physical logic circuits in the guts of the computer.
Open a computer and you won’t see “an image” anywhere. You will see patterns of bits of data in the memory, or on the hard disk, or maybe in transit, being sent to a computer screen. Similarly if you open someone’s skull you will not see an image there either. Just a bunch of neurones in particular states.
The one glaring exception to all the above, is, perhaps, consciousness. It’s hard to describe consciousness in terms of a pattern or patterns of the states of our neurones, but I believe that that is fundamentally what it is.
Some people argue that we are conscious beings, (true), and that we consciously make choices (false, in my opinion). When we look closely at any choice that we make, it appears to be that choice is in fact illusory, and that our actions are determined by prior factors.
People seem to realise this, although they don’t acknowledge it. When questioned, there is always some reason that they “choose” in a particular way. Perhaps they don’t have enough cash to choose the luxury option when out shopping, or their desire outweighs their financial state. When pushed people can always think of a reason.
To be sure, many “reasons” are actually post choice rationalisations, and choices may be based more on emotions than valid rational reasons, but whatever the emotions (such as the desire for an object), the emotions precede decision.
If, as sometimes happens, a person has to make a choice between two alternatives, that person can be almost paralysed with indecision. Even then, when a decision is finally made, it can be either a random choice, or maybe the person may say that they made a particular choice because they had decided a different way in another situation, or similar (e.g. they like the colour blue!).
If there is no non-physical component to the Universe, as appears very likely, and psi phenomenon do not exist, then everything has a cause. I don’t mean this in the sense that event A causes event B which causes C, but more in the sense that the slope that a marble is on causes it to move in a particular direction.
Causality seems to be a continuum thing, rather than the discrete A causes B case. We can only get an approximation of the discrete case if we exclude all other options. There is a latin term for this : ceteris paribus – all other things being kept the same. “Ceteris paribus” would exclude the case where a wind blowing up or across the slope changes the path of the marble.
For this reason I dislike the Many Worlds Interpretation of Quantum Physics, as it is usually stated. The usual metaphor is a splitting movie film, which results in two distinct tracks in the future. I feel that a better picture would be a marble on a slope with a saddle.
The marble may go left, or it may go right, or it may even follow the line of the saddle. We still require “ceteris paribus” to exclude crosswinds, but there is no split as such. In a quantum model, the marble goes both left and right (and traverses the peak of the saddle with vanishing probability).
The probability that it goes left or right is determined by the wave equation for the system, and has a real physical meaning, which it doesn’t (so far as my knowledge goes) in the splitting metaphor.
I don’t know how my speculations stack up against the realities of quantum mechanics, but I like my interpretation, purely on aesthetic grounds, even if it is far from the mark!