Notice I ask what and not when, because ‘now’, as we experience it, is the most ephemeral of all experiences. As I’ve explained in another post: to record anything at all requires a duration – there is no instantaneous moment in time – except in mathematical calculus where a sleight-of-hand makes an infinitesimal disappear completely. It’s one of the most deceptive tricks in mathematics, but in mathematics you can have points with zero dimensions in space, so time with zero dimensions is just another idealism that allows one to perform calculations that would otherwise be impossible.
But another consequence of ‘now’ is that without memory we would not even know we have consciousness. Think about it: ‘now’ has no duration and consciousness exists in a continuous present so no memory would mean no experience of consciousness, or ‘now’ for that matter, because once it occurs it’s already in the past. Therefore memory is required to experience it at all.
But this post is not about calculus or consciousness per se; it arose from a quote I came across attributed to William Lawrence Bragg:
Everything that has already happened is particles, everything in the future is waves. The advancing sieve of time coagulates waves into particles at the moment ‘now’.
For those who don’t know, Sir William Lawrence Bragg was son of Sir William Henry Bragg, whom, as far as I know, were the only father and son to be jointly awarded a Nobel Prize in physics, for their work on X-ray diffraction in crystals. Henry was born in England and Lawrence was born in Australia. I heard about them at school, naturally, but I only came across this quote earlier in the week. They were among the first to exploit short wave photons (X-rays) to find the atomic-scale dimensions of crystal lattices, thus pioneering the discipline of crystallography.
In the same week, I came across this quote from Freeman Dyson recalling a conversation he had with Richard Feynman:
Thirty-one years ago Dick Feynman told me about his ‘sum over histories’ version of quantum mechanics. ‘The electron does anything it likes’, he said. ‘It goes in any direction at any speed, forward and backward in time, however it likes, and then you add up the amplitudes and it gives you the wave-function.’ I said, ‘You’re crazy.’ But he wasn’t.
I’ve discussed in some detail the mathematical formulation of the ‘wave-function’ known as Schrodinger’s equation, in another post, but what’s significant, in regard to the 2 quotes I’ve cited, is that the wave function effectively disappears or becomes irrelevant once an ‘observation’ or experimental ‘measurement’ occurs. In other words, the wave function ‘permeates all space’ (according to Richard Elwes in MATHS 1001) before it becomes part of the ‘classical physics’ real world. So Bragg’s quote makes perfect sense that the wave function represents the future and the particle ‘observation’, be it a photon or electron or whatever, represents the past with the interface being ‘now’.
As I’ve explicated in my last post, the default interpretation of Feyman’s ‘sum over histories’ or ‘path integrals’ mathematical description of quantum mechanics, is that all ‘histories’ occur in parallel universes, but I would argue that it’s a consequence of the irreversibility of time once the particle is ‘observed’. Now ‘observed’, in this context, means that the particle becomes part of the real world, or at least, that’s my prosaic interpretation. There is an extreme interpretation that it does require a ‘conscious observation’ in order to become real, but the fact that the Universe existed many billions of years prior to consciousness evolving, makes this interpretation logically implausible to say the least.
Brian Cox, in one of his BBC TV programmes (on ‘Time’) points out that one of the problems that Einstein had with quantum mechanics is that, according to its ‘rules’, the future was indeterminate. Einstein’s mathematical formulation of space-time, which became fundamental to his General Theory of Relativity (albeit was a consequence of his Special Theory) was that time could literally be treated like a dimension of space. This meant that the future was just as ‘real’ as the past. In other words, Einstein firmly believed that the universe, and therefore our lives, are completely deterministic – there was no place for free will in Einstein’s universe. Interestingly, this was a topic in a not-so-recent issue of Philosophy Now, though the author of the article didn’t explain that Einstein’s strict position on this was a logical consequence of his interpretation of space-time: the future was just as fixed as the past.
But, even without quantum mechanics, we know that chaos theory also contributes to the irreversibility of time, although Einstein was unaware of chaos theory in his lifetime. Paul Davies explains this better than most in his book on chaos theory, The Cosmic Blueprint.
The point is that, both in chaos theory and Feynman’s multiple histories, there are many possibilities that can happen in the ‘future’, but the ‘past’ is only one path and it can’t be remade. According to David Deutsch and Max Tegmark, all the future possibilities occur both in quantum mechanics and at a macro level. In fact, Deutsch has argued that chaotic phenomena are a consequence of the quantum mechanics' many worlds interpretation. In effect, they disassemble the asymmetry between the future and the past. According to their world-view, the future is just as inevitable as the past, because no matter which path is chosen, they all become reality somewhere in some universe; all of which bar one, we can’t see. From my perspective, this is not an argument in support of the many worlds interpretation, but an argument against it.
In my last post but one, I discussed at length Paul Davies’ book, The Mind of God. One of his more significant insights was that the Universe allows evolvement without dictating its end. In other words, it’s because of both chaos and quantum phenomena that there are many possible outcomes yet they all arise from a fixed past and this is a continuing process - it’s deterministic yet unpredictable.
One could make the same argument for free will. At many points in our lives we make choices based on a past that is fixed whilst conscious of a future that has many possibilities. I agree with Carlo Rovelli that free will is not a consequence of quantum mechanics, but the irreversibility of time applies to us as individual conscious agents in exactly the same way it applies to the dynamics of the Universe at both quantum and macro levels.
There is just one problem with this interpretation of the world, and that is, according to Einstein’s theories, there is no universal ‘now’. If there is no simultaneity, which is a fundamental outcome of the Special Theory of Relativity, then it’s difficult to imagine that people separated in space-time could agree on a ‘now’. And yet, the fact that we give the Universe an age and a timeline, effectively insists that there must be a ‘now’ for the Universe at large. I confess I don’t know enough physics to answer this, but quantum entanglement reintroduces simultaneity by stealth, even if we can’t use it to send messages. One of the features of the Universe is causality. Despite the implications of both quantum mechanics and relativity theory on the physics of time, neither of them interfere with causality, despite what some may argue (and that includes entanglement). But causality requires the speed of light to separate causal events, which is why the ‘now’ we experience sees stars in the firmament up to billions of years old. So space-time makes ‘now’ a subjective experience, even to the extent that at the event horizon of a black hole ‘now’ can become frozen to an outside observer.