On the philosophy of reality

 This follows on from my last post, after I saw a YouTube interview with Raymond Tallis on Closer to Truth. He’s all but saying that physics has lost the plot, or at least that’s my takeaway. I happen to know that he’s also writing a book on ‘reality’ – might even have finished it – which is why he can’t stop talking about it, and, it seems, neither can I.
 
I think there are 3 aspects to this discussion, even though they are not clearly delineated. Nevertheless, it might be worth watching the video to better appreciate what I’m talking about. While I agree with some of his points, I think Tallis’s main thrust that physicists contend that ‘reality dissolves’ is a strawman argument as I’ve never heard or read a physicist make that claim. Robert Lawrence Kuhn, who hosts all the talks on Closer To Truth, appears to get uncharacteristically flustered, but I suspect it’s because he intuitively thought the argument facile but couldn’t easily counter it. It would have been far more interesting and edifying if Tallis was debating with someone like Paul Davies, who is not only a physicist, but knows some philosophy.
 
At one point they get onto evolution, as Kuhn attempts to make the distinction between how we’ve evolved to understand the world but culturally moved beyond that. This leads to the 3 aspects I alluded to earlier.
 
The first aspect is that there is an objective reality independent of us, which we need to take seriously because it can kill us. As Tallis points out, this is what we’ve evolved to avoid, otherwise we wouldn’t be here. As I’ve pointed out many times, our brains create a model of that reality so we can interact with it. This is the second aspect, and is part of our evolutionary heritage.
 
The third aspect appears to be completely at odds with this and that appears to be what Tallis has an issue with. The third aspect is that we make mathematical models of reality, which seem, on the surface at least, to have no bearing on the reality that we experience. We don’t see wavefunctions of particles or twins aging at different rates when one goes on a journey somewhere.
 
It doesn’t help that different physicists attempt to give different accounts of what’s happening. For example, a lot of physicists believe that the wavefunction is just a useful mathematical fiction. Others believe that it carries on in another universe after the ‘observation’ or ‘measurement’. All acknowledge that we can’t explain exactly what happens, which is why it’s called the ‘measurement problem’.
 
What many people don’t tell you is that QM only makes predictions about events, which is why it deals in probabilities, and logically, observations require a time lapse, no matter how small, before it’s recorded, so it axiomatically happens in the past. As Paul Davies points out there is an irreversibility in time once the ‘observation’ has been made.
 
The very act of measurement breaks the time symmetry of quantum mechanics in a process sometimes described as the collapse of the wave function…. the rewind button is destroyed as soon as that measurement is made.
 
So, nothing ‘dissolves’, it’s just not observable until after the event, and the event could be a photon hitting a photo-sensitive surface or an isotope undergoing some form of radioactive decay or an electron hitting a screen and emitting light. Even Sabine Hossenfleder (in one of her videos) points out that the multiple paths of Feynman’s ‘sum-over-histories path-integral’ are in the future of the measurement that they predict via calculation.
 
Tallis apparently thinks that QM infers that there is nothing solid in the world, yet it was Freeman Dyson, in collaboration with Andrew Leonard, who used Wolfgang Pauli’s Exclusion Principle to demonstrate why solid objects don’t meld into each other. Dyson acknowledged that ‘the proof was extraordinarily complicated, difficult and opaque’, which might explain why it took so long for someone to calculate it (1967).
 
Humans are unique within the animal kingdom in that we’ve developed tools that allow us to ‘sense’ phenomena that can’t be detected through our biological senses. It’s this very attribute that has led to the discipline of science, and in the last century it has taken giant strides beyond anything our predecessors could have imagined. Not only have we learned that we live in a galaxy that is one among trillions and that the Universe is roughly 14 billion years old, but we can ‘sense’ radiation only 380,000 years after its birth. Who would have thought? At the other end of the scale, we’ve built a giant underground synchrotron that ‘senses’ the smallest known particle in nature, called quarks. They are sub-sub-atomic.
 
But, in conjunction with these miracle technologies, we have discovered, or developed (a combination of both), mathematical tools that allow us to describe these phenomena. In fact, as Richard Feynman pointed out, mathematics is the only language in which ‘nature speaks’. It’s like the mathematical models are another tool in addition to the technological ones that extend our natural senses.
 
Having said that, sometimes these mathematical models don’t actually reflect the real world. A good example is Ptolemy’s model of the solar system using epicycles, that had Earth at its centre. A possible modern example is String Theory, which predicts up to 10 spatial dimensions when we are only aware of 3.
 
Sabine Hossenfelder (already mentioned) wrote a book called Lost in Math, where she challenges this paradigm. I think that this is where Tallis is coming from, though he doesn’t specifically say so. He mentions a wavefunction (in passing), and I’ve already pointed out that some physicists see it as a convenient and useful mathematical fiction. One is Viktor T Toth (on Quora) who says:
 
The mathematical fiction of wavefunction collapse was “invented” to deal with the inconvenient fact that otherwise, we’d have to accept what the equations tell us, namely that quantum mechanics is nonlocal (as per Bell’s theorem)…
 
But it’s this very ‘wavefunction collapse’ that Davies was referring to when he pointed out that it ‘destroys the rewind button’. Toth has a different perspective:
 
As others pointed out, wavefunction collapse is, first and foremost, a mathematical abstraction, not a physical process. If it were a physical process, it would be even weirder. Rather than subdividing spacetime with an arbitrarily chosen hypersurface called “now” into a “before observation” and an “after observation” half, connected by the non-unitary transformation of the “collapse”, wavefunction collapse basically implies throwing away the entire universe, replacing it with a different one (past, present, and future included) containing the collapsed wavefunction instead of the original.
 
Most likely, it’s expositions like this that make Tallis throw up his hands (figuratively speaking), even though I expect he’s never read anything by Toth. Just to address Toth’s remark, I would contend that the ‘arbitrarily chosen hypersurface called “now”’ is actually the edge in time of the entire universe. A conundrum that is rarely acknowledged, let alone addressed, is that the Universe appears to have no edge in space while having an edge in time. Notice how different his ‘visualisation’ is to Davies’, yet both of them are highly qualified and respected physicists.
 
So, while there are philosophical differences among physicists, one can possibly empathise with the frustrations of a self-identified philosopher. (Tallis’s professional background is in neuroscience.)
 
Nevertheless, Tallis uses quantum mechanics just like the rest of us, because all electronic devices are dependent on it, and we all exploit Einstein’s relativity theories when we use our smartphones to tell us where we are.
 
So the mathematical models, by and large, work. And they work so well, that we don’t need to know anything about them, in the same way you don’t need to know anything about all the technology your car uses in order for you to drive it.
 
Tallis, like many philosophers, sees mathematics as a consequence of our ability to measure things, which we then turn into equations that conveniently describe natural phenomena. But the history of Western science reveals a different story, where highly abstract mathematical discoveries later provide an epistemological key to our comprehension of the most esoteric natural phenomena. The wavefunction is a good example: using an unexpected mathematical relationship discovered by Euler in the 1700s, it encapsulates in one formula (Shrodinger’s), superposition, entanglement and Heisenberg’s Uncertainty Principle. So it may just be a mathematical abstraction, yet it describes the most enigmatic features discovered in the natural world thus far.
 
From what I read and watch (on YouTube), I don’t think you can do theoretical physics without doing philosophy. Philosophy (specifically, epistemology) looks at questions that don’t have answers using our current bank of knowledge. Examples include the multiverse, determinism and free will. Philosophers with a limited knowledge of physics (and that includes me) are not in the same position as practicing physicists to address questions about reality. This puts Tallis at a disadvantage. Physicists can’t agree on topics like the multiverse, superdeterminism, free will or the anthropic principle, yet often hold strong views regardless.
 
I’m always reminded of John Wheeler’s metaphor of science as an island of knowledge in a sea of ignorance, with the shoreline being philosophy. Note that as the island expands so does the shoreline of our ignorance.