God of Many Worlds
In the popular telling, Galileo ran afoul of the Church because he insisted that the earth orbited the sun rather than vice versa. In actuality, the conflict was more about Galileo’s insistence that science should help inform the interpretation of scripture. Today, to varying degrees, most people of faith embrace the role of science in shaping our view of God’s universe and our place within it.
When it comes to quantum physics, faith traditions have much catching up to do. Quantum mechanics poses an interesting problem, in that physicists still argue over profound differences in its interpretation. I will briefly describe why I think the Many Worlds interpretation will ultimately gain broad acceptance, and then I will discuss implications for faith. (A note on terminology should be added. In popular media, the term Multiverse often denotes a Many Worlds reality, but it has other meanings as well.)
To illustrate the Many Worlds picture, we can consider radioactive decay of radon gas atoms. These atoms are found naturally in air, and several million decay within your lungs each year. Each decay ejects a polonium by-product into the lung tissue, and in very rare cases a polonium atom landing at the wrong place leads to lung cancer and death. Since quantum mechanics governs radioactivity, each polonium atom shoots off simultaneously in all different directions at once. This is a very strange statement. It would not be strange for the direction to be well-defined but simply unknown. But physicists agree that quantum mechanics says something different: each polonium atom actually travels in mutually contradictory directions until its location is measured, for instance by your lung tissue.
The point of physicists’ disagreement is about what happens next. The original formulation of quantum mechanics, the Copenhagen interpretation, says that large objects do not follow quantum rules. So, when your lungs find the polonium to have shot off in one direction or the other, the multiple realities which had existed a moment before are cut off, leaving only one reality going forward. But if quantum physics correctly predicts behavior of individual atoms, why would it not also correctly predict behavior of the collection of atoms making up your lungs? In recent decades, an increasing number of physicists have begun to take that argument seriously. This leads to the Many Worlds interpretation, in which large things can also exist in contradictory states — each one of these contradictory realities effectively a different World. Unlike for atoms, your lungs are too complicated for us to verify their contradictory state, so their behavior appears to follow the Copenhagen rules. We now know that the Copenhagen add-on to the simpler quantum rules, besides being self-inconsistent, is completely unnecessary to make correct predictions. In science, the simplest theory that explains the data is most often correct. So, many physicists like myself argue that the Copenhagen interpretation is probably wrong, leaving us with a Many Worlds reality.
The simple quantum rules predict that large things, like you and I, only experience one World or another. You either have lung cancer or you do not. But the full picture of reality consists of many disconnected Worlds, in which other versions of you have very different life experiences, or in which you never existed at all. You have around a 1 in 70,000 chance per year of dying of radon-induced lung cancer. So, there are real Worlds in which a radon event will lead to your death, but they are handily outnumbered by the Worlds in which you survive. However, a substantial risk accumulates over a long line of ancestors. Going back 300,000 years to the first Homo Sapiens, there is a sizeable chance that a radon-induced death cuts off an otherwise viable family tree. The odds of each ancestry tree surviving to the present day turn out to be around 1 in 3. That means that in over half the present-day Worlds, one of your ancestors died before reproducing, so you do not currently exist. And the fraction of Worlds containing you plummets further when we consider other quantum hazards your ancestors faced, along with the fact that quantum fluctuations in the early universe most often did not even lead to formation of planet Earth.
What are the implications of a Many Worlds reality for people of faith? For one, science has again found reality to be more magnificent than we had imagined. Continuing revelations about the vastness of the universe have already encouraged worshippers to view God as bigger than we had before. A Many Worlds reality now makes God, who evidently weaves an uncountable number of stories about immeasurably large universes, all that much more awe-inspiring.
Second, any sense of personal destiny needs to be held with a large dose of humility. You do not have a single destiny. Branching from this moment, there will be many future versions of you, each experiencing different realities. Likewise, the familiar question: “Could things have been different?” takes on a new flavor. Yes, things often could have been different. And in fact, they were for different versions of you. As a personal example, at age 46 I was diagnosed with a slowly progressing type of brain cancer. Occasionally it is tempting to lose faith and ask, “God, could you not have planned a better future for me?” A Many Worlds reality makes asking those questions less compelling, since after all there are Worlds in which I never existed. Instead, I find myself thankful for the existence of my experience. And I choose to trust that God’s presence will go with me (or more precisely all versions of me) into all future Worlds branching from this moment. It is also sometimes tempting to ask whether different past lifestyle choices might have given my body a better chance of preventing the cancer. For all I know, there could be parallel versions of me which are still completely healthy. Be that as it may, this World is real and beautiful, and my response needs to be, “God, yes to you in this World.”
Finally, in a Many Worlds reality, there are Earths in which Jesus of Nazareth was never born. How, then, should Christians view Jesus? We could imagine that God sends to each of these Worlds a unique Incarnate Messiah, who undergoes an atoning death and resurrection. But spread across an immense number of different Earth histories (and any alien civilizations), this picture begins to feel contrived. More compelling to me is the theology of the universal or “cosmic” Christ, which describes a picture of God being Incarnate in all of the universe. There is no bit of matter not imbued with God’s presence, and the invitation into the Christ mystery takes on many forms. This theology is also helpful in the single World of our experience, in which there are many cultures which have heard nothing, or at least nothing compelling, about Jesus. Christians can embrace the creeds as describing our mode of interaction with Christ, and at the same time acknowledge that they represent but a window into a larger reality.
People of faith have a spotty history when it comes to being receptive to science. Given that physicists have not yet agreed upon the correct interpretation of quantum mechanics, it would be unbecoming for believers to prematurely declare their loyalty to a Many Worlds viewpoint. But wouldn’t it be interesting for people of faith to be ahead of the game, cultivating an openness to this uncomfortable picture of reality?
Further Reading
MIT physicist Max Tegmark published an introductory article Many Lives in Many Worlds in Nature; a free version of the article can be found here. Caltech physicist Sean Carroll wrote an excellent and accessible book Something Deeply Hidden, a good read for both non-experts and physicists. And I have written a longer version of this piece, which can be found here.
Brian Odom is a Professor of Physics and member of the Center for Fundamental Physics Northwestern University, and a member of Saint Chrysostom’s Episcopal Church in Chicago.
