The particle physics community is not too happy right now. About a month ago, they found themselves yanked into an unexpected debate. The point of contention was whether to build a $22-billion giant collider, a project overwhelmingly supported by particle physicists.
It all started with an op-ed by Sabine Hossenfelder, a theoretical physicist who had started her career as a particle physicist, in the New York Times.
Physicists typically present a united front on questions of funding but Hossenfelder’s write-up was a surprising departure from this norm. Hossenfelder contended that a new collider was just not a good investment for particle physics at this stage, even as particle physicists were misleading the public that new discoveries were around the corner.
An explainer appeared shortly after. Since then particle physicists have been presenting their rebuttals on other news sites, blogs and of course, social media. Hossenfelder’s Facebook page has been debate central for the past few weeks.
An important lesson physicists have learned is that the laws of nature are structured like a Matryoshka doll. The key to unraveling them is energy. At higher and higher energies, more and more hidden rules of nature come tumbling out. This is what collider are used for: they smash particles together at very high energies to reveal these otherwise inaccessible rules.
The Large Hadron Collider (LHC) in Geneva will soon reach the limit of its ability to amp up energy and CERN has already released the plans for a bigger, better machine called the Future Circular Collider (FCC). If approved by policymakers, it will be built by 2050.
On the theory side, our entire knowledge of particle physics can be summed up within a single, 40-year-old rulebook called – simply and stolidly – the Standard Model. Everything we have observed in the LHC had already been predicted by the Standard Model.
In the years since the Standard Model, particle physicists have come up with a plethora of models that try to go beyond it, to uncover the laws of ‘new physics’ deeper than the model itself. The physicists have postulated new particles, new symmetries of nature and even new dimensions of varying sizes. However, none of them have turned up in the LHC.
We do know that more discoveries wait to be made at at enormously high energies, far too high for any collider on Earth. But for energies that a collider on Earth can reach, is Standard Model the last of the Matryoshka dolls? Or is there anything more to find?
This is where opinions vary and the debate begins.
Hossenfelder has alleged that the particle physics community hasn’t presented an honest case to the public for the FCC. The advertisements always emphasise the new particles and exotic dimensions – exactly what they’ve failed to find.
She’s also maintained that there’s no compelling theoretical reason to expect anything new will turn up in the FCC. This is especially so since none of the models that that physicists came up with after the Standard Model have made a single correct prediction.
One could counter-argue that new particles and/or dimensions could be hiding at energies just out of the LHC’s reach, and it’s possible that the FCC will find them. But the same argument could also made if the FCC does not find them. So then should we keep building colliders till we find anything new?
Hossenfelder believes that it is time to stop.
She advances an alternative: instead of spending $22 billion on a single experiment, conduct a range of less expensive experiments that could give us a better idea of what to look for. We should start planning the next collider when we know where to look.
Several other physicists have penned multiple rebuttals. One of their points is that even if nothing new is found, the experiment will still be of value. They will help rule out unviable models – which in itself would be an important discovery. For another: there’s more juice to be extracted from the Standard Model yet. Many physicists are working on using the Standard Model to make predictions that can be confirmed or ruled out only with an FCC-type machine.
Finally, while $22 billion is indeed a lot, it is not prohibitive when spent over 30 years and by several countries together.
Overall, particle physicists feel it’s not time to throw in the towel yet.
As this debate plays out in the public eye, it highlights an important lesson for the scientific community: that communicating science to the people is now more important than ever.
When Hossenfelder had been making the same arguments in her blog, she was largely ignored. It was her article that forced prominent particle physicists to respond.
In fact, many particle physicists are also unhappy with the airtime Hossenfelder has been getting. They feel that a non-particle physicist does not deserve a public platform to criticise particle physics. But Hossenfelder has built a public presence by investing time and effort in science communication, on Twitter and Facebook, through her longtime blog and a book last year.
It is also true that particle physicists had not presented their best case for the FCC before the public till this debate forced their hands.
Irrespective of which way the debate swings, it has already shown that the few who communicate science can have a lopsided influence on the public perception of an entire field – even if they’re not from that field. The distinction between a particle physicist and, say, a condensed-matter physicist is not as meaningful to most people reading the New York Times or any other mainstream publication as it is to physicists. There’s no reason among readers to exclude Hossenfelder as an expert.
However, very few physicists engage in science communication. The extreme ‘publish or perish’ culture that prevails in sciences means that spending time in any activity other than research carries a large risk. In some places, in fact, junior scientists spending time popularising science are frowned upon because they’re seen to be spending time on something unproductive.
But debates like this demonstrate the rewards of science communication.
This presents some serious questions for the physics community. Should science communication be encouraged? If so, should it count for tenure? And how do we reward scientists who communicate without punishing those who don’t?
If physicists are to control the public perception of their fields, they will have to decide on these questions sooner than later.
And if the way this debate has proceeded is any indication, communication has helped clarify the positions of both sides and brought out some points of agreement.
All physicists agree that we can’t keep building colliders ad infinitum. They differ on when to quit. Now would be a good time, according to Hossenfelder. Most particle physicists don’t think so. But how will we know when we’ve reached that point? What are the objective parameters here? These are complex questions, and the final call will be made by our ultimate sponsors: the people.
So it’s a good thing that this debate is playing out before the public eye. In the days to come, physicists and non-physicists must continue this dialogue and find mutually agreeable answers. Extensive, honest science communication will be key.
Nirmalya Kajuri is a theoretical physicist. He is currently a postdoctoral fellow in the Chennai Mathematical Institute.