We’re back on our Edge series of concepts scientists wished more people knew about. Today’s entry is Frank Tipler’s Parallel Universes of Quantum Mechanics. Tipler:
In 1957, a Princeton physics graduate student named Hugh Everett showed that the consistency of quantum mechanics required the existence of an infinity of universes parallel to our universe. That is, there has to be a person identical to you reading this identical article right now in a universe identical to ours. Further, there have to be an infinite number of universes, and thus an infinite number of people identical to you in them.
Most physicists, at least most physicists who apply quantum mechanics to cosmology, accept Everett’s argument. So obvious is Everett’s proof for the existence of these parallel universes, that Steve Hawking once told me that he considered the existence of these parallel universes “trivially true.”
Hawking also thought it trivially true that philosophy is useless, itself a philosophical judgment. So perhaps we should seek out a more eminent authority.
Anyway, Tipler says “Everett showed that the consistency of quantum mechanics required the existence of an infinity of universes parallel to our universe.” Everett showed no such thing. Quantum mechanics does not need an infinite number of duplicate universes, along with another infinite number of different universes, to be consist. Everett instead produced a mathematical picture the interpretation of which is up for grabs. Don’t forget: QM is a theory of probabilities, and probabilities aren’t real, i.e. they are not physical entities. The refication of probability in QM is a major problem: see more in this book. I am dubious that “most” physics buy the interpretation that these infinity of parallel universes are real entities and not just parameters in an equation, but I’ve done no survey.
The free will question arises because the equations of physics are deterministic. Everything that you do today was determined by the initial state of all the universes at the beginning of time. But the equations of quantum mechanics say that although the future behavior of all the universes are determined exactly, it is also determined that in the various universes, the identical yous will make different choices at each instant, and thus the universes will differentiate over time. Say you are in an ice cream shop, trying to choose between vanilla and strawberry. What is determined is that in one world you will choose vanilla and in another you will choose strawberry. But before the two yous make the choice, you two are exactly identical. The laws of physics assert it makes no sense to say which one of you will choose vanilla and which strawberry. So before the choice is made, which universe you will be in after the choice is unknowable in the sense that it is meaningless to ask.
To me, this analysis shows that we indeed have free will, even though the evolution of the universe is totally deterministic.
This type of thing leads to exasperation, but proof by exasperation doesn’t count in logic, so we need to take it seriously. Accepting the Many Worlds of Everett, here you are, ready to make a choice. There are (it is said), at the moment, an infinite number of yous standing in line at an infinite number of Baskin Robbins (and they with only 31 flavors!). The universes are identical in every way, down to the quark across the vast regions of space. There are also an infinite number of other universes different in an infinite number of ways.
In your universe you choose, as any sensible person would choose, Moose Tracks. An infinite number of other yous also choose Moose Tracks, and separate infinite yous choose the other flavors. Actually, you don’t choose, since it is quantum mechanics determining that set A of you gets Moose Tracks, set B Chocolate Cherry, set C gets Orange Swirl, and so on. All the choices are filled, and all must be filled. The universes, since the non-choice choices were different, are all now on their own paths, evolving differently. Nobody who eats Moose Tracks acts in exactly the same way as somebody who eats Orange Swirl.
Each time a choice is made, an infinity of universes peel off and wend their own ways. How many choices are made? Oh, many, many. Toss a pebble onto the pavement. Quantum mechanics suggests—this is the formula—that the pebble can take infinitely many end positions, all the way from infinitely over there, to infinitely in that direction. That makes another set of infinite universes pop into existence, to each follow the paths decided by where quantum mechanics puts the infinite pebbles.
That’s a lot of infinities! Infinities upon infinities upon infinities, because stuff is happening all over the place. Think of some remote star and the physical and chemical reactions taking place within. Each reaction in each moment requires another infinity of branching universes. You can’t emphasize enough how many infinities this is, since these reactions are happening already across an infinite number of universes. It’s a lot.
But then, what makes quantum mechanics choose this universe as the one in which I opt for Moose Tracks? Sure, QM makes sure all choices are made. But how? And how does it order the choices? What—what exactly—is driving QM to put what where? Which of the infinite universes gets the pebble at X, and which at X – 17? And why?
Ah. We’re right back to the same problem the original, single-universe QM posed, and the reason for the positing of Many Worlds. How does QM actualize potentialities? How does it select specific outcomes. Nobody knows the answer with ordinary, single-universe QM. Indeed, all we can know is we can’t know (thanks to Monsieur Bell). But something is making the choice, even if we don’t and can’t know what it is. The escape to Many Worlds avoids the question, because that theory says all choices are made. Very well: all are made. But how? The theory still does not say, and cannot say. Nothing has been solved.
So we see, even if Tipler’s interpretation of Everett is right, and there is no, there is zero, observational evidence it is, we still haven’t solved the problem we set out to solve. How does QM choose? All we’ve done if multiplied infinities faster than democracies increase budget deficits. Which is supposed to make the problem.
Before we go, we owe to Tipler to present his solution to the so-called Problem of Evil—which vexes both atheist and theist theories: to atheists, there can be no such thing as evil (or good) yet trying taking an atheist’s wallet; to theists, an Omnipotent God would seem to preclude evil.
Another philosophical problem with ethical implications is the Problem of Evil: Why is there evil in the universe we see? We can imagine a universe in which we experienced nothing bad, so why is this evil-free universe not the universe we actually see? The German philosopher Gottfried Leibniz argued that we are actually in the best of all possible worlds, but this seems unlikely. If Hitler had never taken power in Germany, there would have been no Holocaust. Is it plausible that a universe with Hitler is better than a universe without him? The medieval philosopher Abelard claimed that existence was a good in itself, so that in order to maximize the good in reality, all universes, both those with evil in them and those without evil, have to be actualized. Remarkably, quantum mechanics says that the maximization of good as Abelard suggested is in fact realized.
Is this the solution of the Problem of Evil? I do know that many wonder “why Hitler?” but no analysis considers the fact that—if quantum mechanics is correct—there is a universe out there in which he remained a house painter.
Oh my. If Everett-like universes exist, not only was there a Stalin, ruthless socialist murderer that he was, but there were an infinite other worse Stalins, some that not only killed millions, but who slaughtered billions. And there must have been one who killed everybody, and not just killed everybody, but who tortured them all to death in the worst possible way. And not only must there been such a blood-soaked Stalin, there must have been an infinite number of Maos who committed worse crimes. And not only must there been an infinite number of Stalins and Maos, but there must be—there must be—an infinite number of yous who are worse criminals still!
This is the solution to the Problem of Evil? One doubts.
An irreconcilable flaw of infinite “yous” is that our intellects and wills are not bodies, i.e. not made of physical stuff, and therefore not susceptible to physical forces. There is thus no way to split an intellect since each is unique. Even if you can imagine a way to overcome this, it gives rise to continuity problems.
At this moment in time stands you, ready to make a choice. Forget all other universes and concentrate on the one you are in now, poised. QM makes the choices (however many there are, and this could be an infinite number) and splits the universes. Never mind how. But it must make the splits. It’s not a problem (not really) where these different universes go, but where does the energy come from to make the splits? It must be infinite in extent and infinite in ability. Everything happens instantaneously. Must this Infinite Pool exist outside the universes it is creating? Is it God?
Now there must be a you that persists through each split that is the same since intellects are not splittable. Each split must be accompanied by the creation of a new intellect attached to the new physical stuff, including the new bodies that resemble you (and how is that accomplished?). But you yourself must persist.