TANGLED COSMOS

Dick Pountain /Idealog 356/ 06 Mar 2024 03:39

For all its faults, YouTube is a resource that offers a quite unprecedented breadth and depth of content – all kinds of music, craft, sport, even streaming movies, and both science and mathematics. OK, much of what it offers is of increasingly dubious, click-baity quality, and that even applies to a lot of the science. I view a lot of YouTube mathematics vids, and while they lack the professional depth you can find on Wikipedia, they often make up for that by exploiting visualisation in original and useful ways. Unsurprisingly the science on YouTube is dominated by cosmology and particle physics, those perennial playgrounds for opinionated nerds who know that Einstein or Bohr were wrong (or right, or whatever). To be sure it’s created a handful of stars like Sabine Hossenfelder and Derek Muller who talk sense and explain stuff well, but the nature of the medium means these get drowned out by the charlatans for most non-scientist viewers.

There are however certain ‘brands’ that guarantee seriousness, and one of the best is the Royal Institution, which gave us Humphry Davy, Faraday and Bragg. I always watch their Christmas lecture, because I like bangs, but this year YouTube offered me as follow-up a lecture by Professor Tim Palmer, who I’ll confess to not knowing before. His lecture, which was about uncertainty and probability, more or less blew my mind, and pushed me to read his book ‘The Primacy Of Doubt’ which merely reinforced that effect. 

Palmer studied mathematical physics and became an expert on chaos theory, before turning that knowledge to practical use in weather forecasting. The huge extension of reliable forecasting in recent years, from a couple of days to around a week, is largely thanks to the method of ‘ensemble’ forecasts he pioneered. Shocked by the infamous failure of the Met Office to predict the 1987 UK hurricane, Palmer realised that the deterministic supercomputer models then in use were prone in rare cases to chaotically wrong prediction, which could be alleviated by feeding the model multiple starting conditions that differ by small additions of randomness – instead of a single prediction this produces a brush-like clump of predictions, the central trend of which is more likely to be right.The theory behind his method involves the Lorenz Equations, which describe the behaviour of chaotic dynamic systems. Solving these equations doesn’t lead to single precise solutions, but to infinitely convoluted fractal graphs called attractors. Palmer’s explanation of Lorenz’s discovery in his RI lecture is superb, and he does it without writing any algebra or calculus on the blackboard, admirably accessible. That however is not what blew my mind: that happened when Palmer turned his method to cosmology. 

In addition to his work in chaos theory Palmer (who is now an Oxford Professor of Climate Physics) obtained his doctorate in General Relativity, so it was no surprise that he has tried to bring the two subjects together. Taking off from Einstein’s theory that gravity is the effect of the curvature of space/time by matter, Palmer postulates that rather than being smoothly curved it may be that space/time itself has fractal complexity, sort of like the Lorenz attractors of chaotic systems. I don’t understand his ‘Invariant Set Postulate’ well enough to attempt further explanation here, but well enough to know that if true it would resolve several of the knottiest problems that currently occupy both cosmology and quantum physics. 

Subatomic particles traversing a fractally convoluted space/time would explain quantum uncertainty without having to invent multiple universes, could offer a theory of quantum gravity more plausible than any of the current candidates, and even do away with ‘non-locality’ and the spooky action at a distance that so annoyed Albert Einstein. 

You’ve probably gathered by now that I’m one of those same opinionated nerds that I was deriding above. I’ve ranted in this column before against people who employ their shaky grasp of quantum uncertainty to declare everything from ‘there’s no such thing as reality’, to multiple universes that provide mechanisms for magic and telepathy. As a humble chemist rather than a mathematical physicist I’m not equipped to refute them in the way Palmer may be in the process of doing. I believe that the very real world that we live in is ruled by thermodynamics, not quantum mechanics, whether that be the crappy battery in your electric car, the catastrophic increase in your utility bills, or those massive perturbations of atmospheric energy that we call our climate (and which may yet see the end of us if we don’t start concentrating). Tim Palmer knows that better than almost anyone, and I have no hesitation in recommending that you watch his RI lecture here https://youtu.be/RkiEV47KPX4?si=BvcXzGzhNqOCiAuv.  [

 Dick Pountain is still just about capable of performing useful work on his surroundings]