My boss and I were waiting in a client’s reception. On a TV showing rolling news came a piece reporting the shutdown of CERN for an upgrade. My boss  sighed, ‘All that money, and for what?’ I said, ‘Well, on the scale of things that governments do it isn’t that much. And, so far as we know, the human brain is the only part of the universe able to reflect on the rest of the universe, so maybe things like CERN are part of what we are here for. ‘

Almost exactly a century ago our Friend Arthur Eddington published the first experimental confirmation of General Relativity (GR) showing that ‘modern’ Physics, that is, Physics following Einstein’s Wunderjahr papers of 1905, was not going away. Quantum Mechanics (QM), the other major  branch of modern Physics also has much of its origin in those papers. I believe that it’s also about a century since the Friend carried science articles. This isn’t one, but there might be some catching up to do.

Physics is taught in chronological order starting, roughly, with things known to Galileo, then things known to Newton, and so on. So modern Physics may appear quite late in a person’s education, and perhaps still be presented as a strange departure from the supposedly intuitive, allegedly obvious, ‘classical’ results that the student is familiar with. Eddington’s confirmation of GR was front-page news at the time, seen almost as an overthrow of rationality itself, and modern Physics is still sometimes seen as a way to inject a mysterious kind of flexibility into the subject.

But that’s backwards, both philosophically and in fact. QM, for example, gives predictions entirely consistent with those which classical Physics does, but better—in all situations. Including the world of our every-day experience, of things much bigger than atoms.

In four years at university my Physics didn’t quite get as far as what is investigated at CERN. I’ve picked up a bit more since then. One thing I learned is that there’s a philosophical position hidden inside classical Physics, one that is deeply embedded in western education but does not stand up to detailed investigation. The wonder is not that the universe turns out to be as rich as QM tells us it is, the wonder is that we managed to do as well as we did with such a deeply mistaken set of ideas about it.

There is no ‘wave-particle duality’; so far as we know, matter is explained best by just waves in fields. But waves are subtle and we have very poor intuitions about them. We have learned that waves in fields can do all the things that we used to imagine ‘particles’ did. Things that, we could say, classical physicists created the idea of ‘a particle’ in order to explain. But ‘particles’, imagined as something like very, very tiny billiard  balls, are an explanation that doesn’t stand up to scrutiny. Nor does the idea that the universe is full of objects which fully occupy crisp boundaries, with definite identities, and with intrinsic properties agreed to by all observers. Properties as basic as position in space or state of motion. Rather, the universe seems filled with overlapping, evolving, interacting waves, spread out over time and space, and it matters how we look at them. But we can calculate those evolutions with great accuracy. Heinsenberg’s Uncertainty Principles tell us that for certain pairs of  quantities we will get different pairs of answers depending on the order in which we measure them. But those measurements themselves may be as accurate as we like. Our predictions of what those measurements will turn out to be, using QM, can be very accurate too, but they will be statistical. Random, but not arbitrary. Based on probability, not certainty, but confidently so. QM is not a door to vagueness, it’s the opposite.

QM has almost been too successful: leaping from science to applied science to technology before we’ve managed to work out what it means. Is it true, truly really true, that the universe is made of propagating waves in fields? Maybe, and maybe not. It’s hard to tell. The latter gives much  better results that the former, in all cases, but there are reasons to suspect that other approaches might give yet better ones.

But we can be confident that there will be no return to classical Physics. It just can’t be made to agree with what we see. QM even tells us that the kind of probability and (therefore) even the kind of logic that underpins classical thinking can’t be quite right for the actual stuff of the world. If QM and GR really can’t be merged then we must hope that they will both be replaced by something else, but it won’t be a classical theory. And so Physics seems also to be subject to a continuing revelation. The more we’ve seen, the more we can expect to see. And be surprised by.

Classical Physics assumed that rich behaviour arises from complicated rules underlying a system. Another modern branch of Physics, Chaos Theory, tells us that this is not so. Simple things connected simply, as simple as one pendulum hanging from the end of another, can have arbitrarily rich behaviour. This turns out to be the key to analysing systems like the weather, where our ability to predict precisely declines very rapidly as we look further into the future. And a related field, Complexity Theory, shows how that realisation is also the key to understanding how large-scale order, very regular behaviour across space and time, can emerge spontaneously from the interactions between large numbers of simple entities following only simple, local rules. With no grand design or central organisation. Like shoals of fish, flocks of birds, and maybe many human behaviour too. These, also, are not doors through which comes mystery, they extend the reach of confident calculation, although again of a new  kind.

Modern kinds of Physics, as Eddington said in his 1929 Swarthmore Lecture, have rightly abandoned the earlier search for material, mechanistic explanations and replaced them with natural laws represented in mathematical language. Physics is no longer our every-day intuition and common sense  distilled to a very high degree of purity.

But modern Physics, although all maths all the time, can be a rich source of metaphors. It’s tempting for me to say that a gathered Meeting for Worship does for love what a laser cavity does for light: a wave of it bounces around, creating more of itself from the energy of its interaction with prepared entities, be they people or atoms. Or, perhaps, to say that the richness of a gathered Meeting self-organises out of each attender’s simple waiting on the prompting of the spirit interacting with that of the others present. Or even that ‘God’, in general, emerges out of the interaction between ‘that of God’ in each of us, rather than that of God in each of us being a fragment of a larger thing put there from  outside.

And those are lovely thoughts, but I must beware of extending the metaphors too far.