Marvel’s Loki series has built an interesting narrative on the idea of an infinite multiverse. Anything that could happen (including an alligator with a great Tom Hiddleston grin on its face), has happened. This makes for a rich story telling device. It is the way ahead for Marvel’s Multiverse of Madness phase 4 storyline. But there might be more going on here. Fiction is helping to cement the actual physical idea of a real multiverse into the public consciousness. The idea of a multiverse crops up in both science and science fiction.
The multiverse is how some scientists account for the fine tuning of the universe for life – without resorting to God as an explanation. Physicists Andrei Linde, Alan Guth, and Paul Steinhardt have proposed a scientific model called Inflationary Cosmology, while other physicists have proposed String Theory. You cash out the details in different ways, but you end up with:
1 – Our universe is finely setup for life to exist.
2 – There are an infinite number of different universes.
3 – There is a high likelihood of life sustaining universes coming into existence.
4 – We are just lucky to live in a life sustaining universe.
MIT physicist Max Tegmark has gone further to say that, “all structures that exist mathematically exist also physically.” If you can think of a structure that is mathematically possible, then because there is an infinite multiverse, that structure isn’t just an idea. It actually must exist! So – hello Gator Loki.
However – there is a big epistemological cost to this idea. Stephen C. Meyer points out the cost in two ways.
The Cost of Our Rationality
The infinite multiverse means that any event- however unlikely – has actually occurred an infinite number of times. One such event is the sudden appearance (through quantum fluctuations of subatomic fields/particles) of a brain with preset memories and an ability to perceive a limited universe. These are called Boltzmann Brains after 19th century physicist Ludwig Boltzmann. They pop into existence for a while – and then pop out of existence again.
If physicists posit a multiverse to explain the fine tuning of the universe for life, then this also must lead us to doubt the reliability of our own minds because it is more likely that we are Boltzmann Brains than individuals in a naturally complex and populated universe. And if that is the case – our scientific reasoning abilities, perceptions, and our basis for accepting the multiverse hypothesis are all undermined. The infinite multiverse is a self-refuting hypothesis.
The Cost of Scientific Prediction
If we live in an infinite multiverse, then what can we say about our understanding of the laws of nature? Take the law of gravity for example? Well – we can say that so far – the behaviour of nature is such that the law of gravity leads us to expect certain behaviours. For example, the dropping of an apple from the branch of a tree to the ground. But because anything that could happen must happen in an infinite universe, we must also face the possibility that at some arbitrary point in the future, the natural laws will diverge and begin to behave in unexpected ways. Apple’s can start to fall up, for example. This is because for all we know, the mathematical laws describing the universe are not fully understood by us yet and are controlled by a wider and more general equation that will lead nature to behave differently in the future. We cannot rule out this possibility. But that means we can no longer confidently predict scientifically whether or not events will happen based on our experience of the past. Stephen Meyer puts it this way:
“Scientific explanation presupposes the uniformity and regularity of nature, including the uniformity of the fundamental laws of physics and the regularity of patterns of cause and effect [but] such uniformity and regularity may not characterize our universe, however much it might have seemed to do so up until this point.” We might think we are experiencing cause and effect in nature. But what we don’t realise is that actually, we have been experiencing random fluctuations and nature will behave differently in the future compared to the past. Science as we know it – ceases to be helpful.
If we accept the thesis that we live in an infinite multiverse, then we must also accept two additional conclusions. We cannot be sure that we are rational, and we cannot rely on our ability to make scientific predictions.
Both of these conclusions undermine the multiverse hypothesis and the practice of science – so – I would suggest we cannot live with these conclusions. They are not logically sound. And so this is a strong reason to reject the multiverse in physics, look for another theory to explain the fine tuning of the universe.
Having said all of that – roll on season 2 of Marvel’s Loki!
 Stephen C. Meyer, Return of the God Hypothesis, (HarperOne, 2020), 394.
 Ibid., 401 – 402.
 Ibid., 396.