Is the universe fundamentally predictable or unpredictable? Does the degree to which the future remains unknown reflect our own cognitive limitations, or the fundamentally open structure of reality? Earlier this week a remarkable panel comprising of Lee Smolin, Francesca Vidotto and John Vervaeke debated these questions during an IAI Live event, streamed in real time from the Institute of Art and Ideas in London. The universe, the panelists agreed, is a place of constant change and surprise, and its future remains fundamentally open.
The next IAI Live event, ‘Quantum Physics and the End of Reality’ is FREE and will take place on July 25th. Sabine Hossenfelder, Eric Weinstein, Carlo Rovelli and Brian Keeting debate quantum mechanics, consciousness and the observer effect. Learn more here.
Arguably the success of the natural sciences, physics in particular, is measured in terms of its predictive powers. Even quantum mechanics, a theory that challenged the deterministic picture of reality, still makes predictions, albeit probabilistic ones, with great accuracy – the greatest of any theory so far. But is this idea that reality has a certain order, that the future will resemble the past, and that we are capable of identifying the patters that help us navigate time true? Or is reality and the future radically open, unpredictable, and capable of surprising us?
These were some of the questions that radical theoretical physicist Lee Smolin, professor of physics, astronomy and philosophy Francesca Vidotto, and professor of cognitive science, John Vervaeke, tackled during a live online debate for the Institute of Art and Ideas earlier this month. The discussion ended up focussing less on the cognitive limitations of humans and more on the very nature of reality itself and the extent to which it lends itself to predictability. Then again, John Vervake argued that there is a lot more continuity between the cognitive structure of the human mind, and the structure of reality itself.
Lee Smolin kicked off the discussion by saying that while we can of course predict some things, the idea that the future is entirely predictable is part of a metaphysical fantasy based on a particular conception of the laws of nature. For him, the best expression of this Newtonian paradigm of determinism is found not in the writings of Sir Isaac, but the playwright Tom Stoppard. In his famous play Arcadia, the character of Thomasina is fascinated by the idea that the future is, in principle, knowable:
“If you could stop every atom in its position and direction, and if your mind could comprehend all the actions thus suspended, then if you were really, really good at algebra you could write the formula for all the future; and although nobody can be so cleaver to do it, the formula must exist just as if one could.”
For Smolin, the universe is best thought of not as a collection of things but of events, constantly created by time. According to this picture, which echoes the French philosopher Henri Bergson, the future remains radically open.
This picture of reality, Smolin argued, seductive as it is, is dead and the reason for that has to do with the ontology on which it’s based. Newton’s universe was made up of billiard balls, bouncing against each other in accordance with strict laws of motion. But for Lee Smolin, the universe is best thought of not as a collection of things but of events, constantly created by time. According to this picture, which echoes the French philosopher Henri Bergson, the future remains radically open, and the past is there only insofar as it’s reflected in present knowledge. Only the present is real.
Francesca Vidotto, co-author with Carlo Rovelli, of Covariant Loop Quantum Gravity, presented a more mainstream picture of how physics thinks about prediction. As a cosmologist, Vidotto explained, she is used to looking at a picture of the universe, and then running the film, as it were, backwards, to see what happened in the past. We can do the same for the future, she argued, and predict things like the eventual heat death of the universe. The main qualification Vidotto made was that these pictures of the universe in was in the past and as it will be in the future that physics puts together are very coarse-grained. The detail of each picture remains rather fuzzy.
John Vervaeke suggested that we start by drawing a distinction between two ways of thinking about prediction. On the one hand we think of prediction in nomological terms, using laws of nature to predict natural events at a grand scale. On the other hand, we think of prediction in terms of a very particular causal pathways that lead to particular events, say Napoleon’s defeat at Waterloo, and which don’t lend themselves to nomological descriptions, but to narratives. This distinction is reminiscent of the one Neo-Kantian philosophers drew between the explanations available to the natural sciences and those available to the human sciences. Neo-Kantians wanted to stress that the nomological framework of the natural sciences is not applicable to the human sciences – looking for laws of history which we can use to predict future historical events is futile. We should also resist, they argued, the idea that the narrative framework of the human sciences is somehow ultimately reducible to nomological explanations, like Thomasina thought. It's not that the phenomena that history describes are too complex for the human mind to be able to explain using the laws of motion - they are simply phenomena of a different kind from those that physics studies.
What if there is a deep connection between our cognitive structures and the structures of reality, wondered Vervaeke.
In this sense, Vervaeke agreed with Smolin – the demand for certainty in our predictions is premised on a deterministic picture of the universe, epistemology and ontology are linked here. He also agreed that this picture of reality has been deeply undermined – nature is not deterministic. But instead of following the neo-Kantians who, as Kant, remained agnostic about the ultimate nature of reality, seeing the different explanations of physics and history as simply two different cognitive frameworks that we apply to reality, Vervaeke made a surprising claim. What if there is a deep connection between our cognitive structures and the structures of reality? It is possible, of course, that the mind is operating according to principles radically different from reality, and that intelligibility, the fact that reality seems to make sense to us, is an illusion, a projection on our part. That’s the Kantian story. But what if what we take to be real and what we take to be intelligible are not separated by an enormous gulf, but are one and the same thing. That’s what Kant’s successor, Hegel, thought and it sounded like Vervaeke had arrived at the same idea through cognitive science.
If we follow this idea that intelligence and reality are structured in the same way, Veraeke says, then reality would have to mirror the fundamental features of our cognition: It would be part algorithmic, following strict rules, and part arbitrary.
As a follower of Leibniz’s philosophy, and a believer in the principle of sufficient reason – the idea that all events can be given a rational account - Smolin agreed with Vervaeke that the universe should be intelligible. But in order for the universe to be intelligible, according to Smolin, we must be able not only to find the underlying laws that govern it, but also why the universe is governed by such laws. At this point he quoted Charles Peirce:
“To suppose universal laws of nature capable of being apprehended by the mind and yet having no reason for their special forms, but standing inexplicable and irrational, is hardly a justifiable position.”
As with Peirce, Smolin argues that the best candidate for an explanation of why the laws of nature are what they are is evolution: in the same way that complexity in living organisms evolved through a process of natural selection, something equivalent must be the case for why the universe has developed the way that it did, and has the laws that it does.
Being and becoming are not polar opposites, as Parmenides and Heraclitus thought, but intertwined. Why this is so is the greatest question in physics, according to Vidotto.
Vidotto agreed with the sentiment of Smolin’s approach. Of course the laws of physics are not given by God, or something else external to the universe. They emerge from within it. She did point out, however, that Smolin’s picture almost pushes the issue back a step. We might be able to explain how laws evolved naturally, but is that evolution itself not governed by a meta-law? If so, how do we explain how that came about?
Where she did agree with Smolin is that the old picture of the world as composed of objects has been left behind by modern physics. And while she thinks time is emergent, she sees change as fundamental. Our universe is made of processes, not objects: something exists only insofar as it is interacting with something else. Being and becoming are not polar opposites, as Parmenides and Heraclitus thought, but intertwined. Why this is so is the greatest question in physics, according to Vidotto.
Bu this still doesn’t tell us whether those processes are predictable, or chaotic.
Vervaeke had the last stab at this central question of the debate. As we saw, according to his continuity hypothesis, our cognitive structures are continuous with biological life, and perhaps even more fundamental structures of nature. Cognition, therefore, is best understood as an evolutionary phenomenon – as an ever-modifying feedback cycle between models and data. This means that not only does the mind think in evolutionary terms but is itself a part of this evolutionary cycle. "Our cognition is part of the ontological processes of nature!" he explaimed.
Vervaeke argued that the two ways that our minds understand something to be real are: 1. That which conforms to our current mode of intelligibility, that which is predictable, if you like and 2. That which doesn’t fit within our current mode of intelligibility, that which surprises us, that’s unpredictable. Guided by the idea that our cognitive processes are part of nature’s processes, it follows that the universe is sometimes orderly and predictable, and sometimes chaotic and unpredictable.
Lee Smolin couldn’t contain his enthusiasm as he saw a deep affinity between his ideas of how the universe develops by learning, and the ones Vervaeke was putting forward. For Smolin, one way of thinking about how laws develop within the universe is by a principle of precedence. Faced with a certain set of circumstances, the universe “looks to its past” and “remembers” how it reacted previously. When this happens over and over again, the behaviour of the universe begins to converge towards definite laws. The question though is, what happens when the universe runs into a situation that has no precedent? Then, the universe has to do something new and unpredictable. Vervaeke was similarly enthusiastic and surprised hearing echoes of his thinking from a physicist.
Sometimes we don’t need the universe to tell us reality can be open and unpredictable – all we need is to talk to each other and be surprised.