Physics’ unsolved problems

Brian Cox is possibly the only particle physicist on Earth who is the subject of a book that claims to be an “unauthorised biography”.

Contrary to expectations, though, the book, published in 2015 and written by Ben Falk, is not about Cox’s early career as a pop star in the 1990s Northern Irish dance outfit, D:REAM. Rather, according to the blurb, it concentrates on how “his affable charm and infectious enthusiasm have brought science to a whole new audience”.

The contention is certainly true. In recent years he has written and fronted several blockbuster science television series, including The Human Universe and the forthcoming The Forces of Nature.

For 14 seasons he has co-hosted, with Robin Ince, the popular BBC radio program The Infinite Monkey Cage. In between he’s popped up on panel shows, in the rebooted Monty Python stage production, and in specials such as “The Science of Dr Who”.

In August he’ll be doing a speaking tour of Australian mainland capitals. Of course it will sell out. And of course he’ll be a special guest on every TV show that can get him. He’s a celebrity, after all.

Given all that, it’s easy to forget that he’s also a very serious scientist. Among other things, he holds research posts at the University of Manchester, CERN and the Large Hadron Collider. When free from his recording commitments, he is part of an international team working on the installation of proton tagging detectors for use in refinements of the collider’s ATLAS and CMS experiments.

He’s publishing, too. In June this year he was a co-author – admittedly with 5,112 others – of at least one paper lodged on preprint site arXiv. The paper is titled “Measurements of the Higgs boson production and decay rates and constraints on its couplings from a combined ATLAS and CMS analysis of the LHC pp collision data at s√= 7 and 8 TeV”  – which, just by itself, slates home that the good professor, despite what the music mags used to say, is far from just a pretty face.

While his day job concerns playing close attention to subatomic particles, it doesn’t at all preclude his thoughts turning to matters macro.

The possibility of life beyond earth is one such area. In The Human Universe he led the somewhat depressing argument that, while life per se might be abundant in the cosmos, humanity could well be the only intelligent, civilisation-building example of it in this galaxy. This is in part, he said, because the development of eukaryotic cells was so vanishingly unlikely, the chances of it happening twice in planets orbiting our 300 billion local area stars is exceedingly remote.

Of course, there is much unknown – indeed, unknowable – beneath such a statement, because all species on Earth stem ultimately from a single common ancestor. In terms of types of life, this presents a sample size of just one – never a reliable number from which to draw conclusions.

Because of that, it invites the question of whether life evolving once only is always the name of the game, or whether two or more entirely separate life-systems can share a planet.

“There’s an argument that there’s a sense of inevitability about geochemistry turning into biochemistry in the right circumstances,” says Cox.

“The theory that I think is the most promising is the idea that in hydrothermal vents in an ocean, in those kinds of conditions where you get an energy flow – an out-of-equilibrium situation – where you get acid and alkaline together, hot and cold together, biochemistry may be inevitable in those conditions.

“The counter argument is what some evolutionary biologists say: once you get a life, once you get a replicator, it’s then very difficult for another replicator to get a foothold because the head start you get by being the first replicator is immense.

‘I’d say we’re sure now that dark matter must be some kind of particle. It would be a very strange thing if it wasn’t’

“You get access to natural selection straight away, and off you go. The advantage to being first is colossal.”

Cox’s own opinion? “Honestly? I don’t know.”

And that, of course, is how it should be. However much certain crusty parliamentarians and commentators may like to deride them, doubt and uncertainty are essential elements in the scientific process.

This is so, even in areas where evidence appears to be ever bolstering theory. Take the standard model of particle physics, for instance, a model at the heart of Cox’s research.

From the outside, recent discoveries – not least of the Higgs boson and the (albeit contested) detection of gravitational waves – seem to be yet more proof of the model’s robust structure.

Brian Cox has his doubts.

“The standard model, with Higgs, is really not what most people would have expected,” he says.

“It’s not clear that it’s … well, it looks quite ‘fine-tuned’, let’s put it that way. There are more natural models, in many people’s eyes.

“Supersymmetry is a very good example – which also gives you a candidate for dark matter. This is absolutely necessary.”

But the drawback with supersymmetry – where every particle has another twin with higher mass – is that it would be a much better model if there were the slightest experimental evidence that it actually exists. It’s an obstacle, says Cox, but not necessarily a permanent one.

“I’d say we’re sure now that dark matter must be some kind of particle. It would be a very strange thing if it wasn’t,” he says.

“So, it looks like the astronomers are telling us that there must be some other kind of particle out there. And you would expect it in terms of energy – naively – to be around about where the Higgs particle is. So it’s kind of surprising that we haven’t seen any hint of anything like supersymmetry.

“But there’s a lot data still to be taken at the LHC, and I would not be surprised at all if we didn’t see something else. Although it’s possible that we won’t, of course.”

But if they do, it still won’t be the end of the standard model’s faults. Far from it, in fact.

“There are huge unsolved problems in physics at the moment,” says Cox.

“I would say that dark matter is one that should be resolved pretty soon. But dark energy is a colossal problem. There’s something very strange that we don’t understand about the way particles interact with space-time.

“That link between general relativity and quantum theory – there’s something really terribly wrong with our understanding of that.”

And that is significant not just in and of itself. From an anthropocentric point of view, it feeds into an even deeper issue, at least if Cox is right in suggesting intelligent life in the universe is as rare as it is.

Bluntly, if we don’t sort out the friction between the two paradigms, nothing else in the Milky Way will do so, either. Possibly ever.

“The most interesting questions, I think, are questions that appear to have mutually exclusive answers,” says Cox.

“So when you start asking questions, such as how valuable is the human race, I take two views that appear to be opposed.

“One is that physically we’re obviously insignificant. But I think we’re incredibly valuable. The reason for that is that I think in the local universe there are very few civilisations around, so we’re not likely to meet any others.

“You could even argue that there are only a handful, possibly even one. And that’s enough for me to make us valuable.”

Brian Cox, with Robin Ince, will be in Australia from 5-18 August. Details and tickets: https://lateralevents.com/public-events/brian-cox-journey-into-deep-space/

Andrew Masterson’s new book, Lolcatz, Santa and Death by Dog, is published by Ebury, an imprint of Penguin Random House, on 1 August 2016.