What is called the Everett Many Worlds theory is a theory supposedly based on quantum mechanics. The theory holds that every instant the universe is constantly splitting up into an infinite number of copies of itself, so that every possibility (no matter how unlikely) can be realized. The theory has a name that makes it sound not so unreasonable (with all the planets being discovered, the phrase “many worlds” doesn't sound too farfetched). But the name “many worlds” doesn't describe the nutty idea behind the theory. The theory would be more accurately described as the theory of infinite duplication, because the theory maintains the universe is duplicating itself every second. Or we might also call the theory “the theory of infinite absurdities,” since it imagines that all absurd possibilities (no matter how ridiculous) are constantly being actualized.
There is no evidence whatsoever for this theory, which is endorsed by only a minority of theoretical physicists. The Everett Many Worlds theory has been firmly rejected by physicists such as Adrian Kent, T. P. Singh (who says it has been falsified), and also Casey Blood, who calls it “fatally flawed.” No one has ever observed a parallel universe. We also cannot plausibly imagine such a theory ever being verified. To verify the theory, you would need to travel to some other universe to verify its existence, which is, of course, impossible. Even if you did travel to such a universe, you could never verify the idea that every possibility is occurring in other parallel universes.
It is sometimes claimed that the Everett Many Worlds theory is “supported” or “implied” by quantum mechanics, but that statement is not correct. It is merely correct to say that quantum mechanics is the springboard or diving board from which people leap to the theory of infinite parallel universes, rather like a man jumping from a high Olympic diving board into an empty swimming pool. Because quantum field theory makes the worst prediction in the history of physics (that every cubic meter of a vacuum has more mass-energy than the entire mass-energy in the observable universe), and because quantum mechanics is inconsistent with the well-established theory of general relativity, we are many decades or centuries from being in a position where quantum mechanics can be credibly used as the basis of any vast theory with sweeping consequences, any theory such as the Everett Many Worlds theory.
In order for our universe to split up into other universes, you would need for new matter to be constantly created. Not just a little matter. The Everett Many Worlds theory basically requires that every instant an infinite amount of mass-energy be created – for how else could one universe constantly be splitting up into an infinite number of copies of itself? The problem with that is that it is a known law of nature that mass-energy cannot be created. This law is called the law of the conservation of mass and energy.
What is the proper term to describe an incredibly bizarre belief which is eternally unverifiable, and which violates a known law of nature? The correct term is: delusion. When discussing belief in the Everett Many Worlds theory, the term we should be using is: the parallel universes delusion.
The definition I am using for delusion is the first one I get when doing a Google search for that definition: “An idiosyncratic belief or impression that is firmly maintained despite being contradicted by what is generally accepted as reality or rational argument.” The parallel universes theory meets that definition. The theory involves a supremely idiosyncratic idea that is dramatically in conflict with what is “generally accepted as reality,” which is that there is one instance of each of us, not an infinite number of copies of each of us.
Vision disorder reminiscent of parallel universes theory
Now, you might argue: you can't prove that there aren't an infinite number of parallel universes, so the theory isn't a delusion. But an idea can be a delusion even if it can't be proven wrong. If you believe you created the Andromeda galaxy in a previous incarnation as a deity, there's no way to prove that wrong. But such a belief would be an incredibly bizarre unsubstantiated belief which could never be proven. So it would be absolutely correct to call it a delusion.
Is is it fair to use the term delusion in talking about a belief in parallel universes? After all, delusion is a very strong word, which almost implies a kind of psychiatric problem. But I don't think such a word is too strong. To illustrate the point, let us imagine a case of a man James who has been charged with killing a man named John Doe. James undergoes a psychiatric evaluation. Now James is a firm believer in the Everett Many Worlds theory, the idea that every second our universe is splitting up into an infinite number of parallel universes. The interview goes something like this.
Psychiatrist: Good morning. Let's begin the court-ordered psychiatric evaluation. You've been charged with a serious crime, the murder of John Doe. So I have to determine whether you have a firm grip on reality. Now let me ask you: did you kill John Doe?
James: Well, I did, and I didn't.
Psychiatrist: You did, and you didn't?
James: You see, there was one me who did kill John Doe, and there was one me who didn't.
Psychiatrist: Fascinating. So it seems that you have a kind of split personality.
James: No, it's not like that. It's that there's one world in which I killed John Doe, and another world in which I didn't.
Psychiatrist: My goodness, this is an even more fascinating case of pathology. So you think there are two you's?
James: No, no, Doctor, it's not like that.
Psychiatrist: Oh, I'm sorry. I didn't mean to put words in your mouth. So how many you's are there?
James: There are an infinite number of me's.
Psychiatrist: Really? So how many of those you's killed John Doe?
James: Well, an infinite number of me's killed John Doe, and an infinite number of me's did not kill John Doe. Plus there were an infinite number of me's who killed you, and your mother, or any other single person in this city.
Psychiatrist: So are you saying you've killed me an infinite number of times?
James: Yes, there have been an infinite number of me's who killed you, but don't get the wrong idea. There have also been an infinite number of me's who killed some other person, plus also an infinite number of me's who did not kill anyone.
Now I ask you: would it be fair for this psychiatrist to use the word delusion in discussing the beliefs of James? I think it would be absolutely fair. James suffers from an utterly irrational, gigantically bizarre and totally unverifiable belief for which there is no evidence, a belief that scrambles most of the normal notions of reality, making James sound like some psychiatric inmate. It would be perfectly fair to use the term delusion to refer to that belief. Similarly, it is correct to use the term “the parallel universes delusion” when speaking of the Everett Many Worlds theory, which postulates just what James described in his interview.
Two months ago a 39-year old JP Morgan executive jumped to his death from a high floor of a skyscraper. His girlfriend said that he had an obsession with the idea of parallel universes. Apparently the man was familiar with two other young believers in parallel universes who had killed themselves.
No one should be the least bit surprised when a believer in an infinity of parallel universes commits suicide. When a man holds the belief that all possible scenarios are just as real as observed reality, and that any possible outcome is occurring an infinite number of times, he is apt to think that it makes no difference what he does, and that it makes no difference whether he lives. A belief in an infinity of parallel universes is a poisonous prescription for complete moral indifference, and suicide is a very possible side effect of that prescription.
All I can say is: irrational beliefs lead to irrational conduct, and a belief in an infinity of parallel universes is an utterly irrational belief. Keep your grip on reality, and avoid this crackpot misbegotten theory like the plague. Do not flatter yourself by vainly imagining that there are an infinite number of you's scattered across parallel universes. You are the only you.
Postscript: See this recent post by physicist Lubos Moti Pilsen, who dismisses the Everett Many Worlds theory as pseudoscience that is "fundamentally wrong." Pilsen makes many other good points I didn't make in this post.
Post-postscript: See here to see a quote by a physicist Theo Nieuwenhuizen on the Everett Many Worlds theory:
But one thing is clear already: the many worlds idea about quantum mechanics is a mistaken, nonsensical issue. I spent 15 years on studying what goes on in quantum measurements, the only point of contact between the quantum framework and the reality of tests in detectors. We have good results and a good picture of what goes on. What is very clear: the many worlds idea comes in nowhere and it has nothings to to with the whole subject. It is a lot of talking about a misconceived structure of the theory.