Are Particle Physicists Inventing New Particles for No Reason? No, but It’s Complicated

Has the entire field of particle physics collapsed, thanks to the efforts of a former physicist who is now speaking out? If you’ve read the latest headlines, you might be inclined to think so. 

On Monday, the Guardian’s opinion section ran an article by astrophysicist and YouTuber Sabine Hossenfelder that claimed particle physicists have been harboring a dark secret: They “do not believe the particles they are paid to search for exist.”

In a nutshell, Hossenfelder says that theoretical particles are being conjured up out of thin air to explain some of the anomalous findings physicists have seen in particle colliders and high-energy physics experiments. She contends that an entire “zoo” has been invented featuring an array of strange particles like “wimps,” “axions” and “sterile neutrinos.” 

As she notes in her piece, particle physicists have been looking for the inhabitants of the “zoo,” but experiments designed to find them haven’t discovered anything. So, she writes, researchers are wasting time looking for made-up particles beyond the Standard Model, which she believes “works just fine the way it is.” Many particle physicists disagree with that idea, noting in particular that it doesn’t describe dark matter.

Still, by “inventing” new particles beyond the Standard Model, Hossenfelder appears to suggest that researchers are only serving themselves: They’re able to write highly theoretical scientific papers, boosting their publication numbers and racking up citations — which have great value when trying to get more funding. 

Worryingly, this claim inspired other publications to jump on the controversy. One headline screamed “FORMER PARTICLE PHYSICIST ABSOLUTELY ANNIHILATES THE FIELD OF PARTICLE PHYSICS” and suggested particle physicists had a “dirty secret.”

But the truth is far less alarming (and requires far less Caps Lock.)

Speaking to particle physicists over the last week, it’s clear Hossenfelder’s claims rankled the field. “It truly hurts me,” Thomas Van Riet, a physicist at KU Leuven in Belgium, told me via email.

Many view the framing of Hossenfelder’s article as unfair. Some believe it simply contains mistruths and false information. The major concern I’ve heard is how Hossenfelder presents particle physicists working “in private” as if they’ve been acting conspiratorially, keeping the truth about their work from the public. “What’s most annoying to me are the claims of what is said behind closed doors,” tweeted Djuna Croon, a theoretical physicist at Durham University, in response to the article.

Hossenfelder points out she used to be a particle physicist and has now “left the field.” This distance, she writes, renders her “able and willing to criticize the situation.” However, it may leave readers thinking that basically every working particle physicist is somehow untrustworthy.

It’s kind of like a chef eating at a restaurant besides the one they usually cook at. The restaurant they visit might serve up bland, boring soup that’s way overpriced. But then the chef says “this whole neighborhood of restaurants is terrible and they charge too much for soup,” even though there’s a whole street of restaurants selling cheap, delicious soup just around the block. In short, tarring a whole field with a single brush is unjustified and doesn’t capture the truth of the situation. 

That’s not to say there aren’t good points in Hossenfelder’s piece and particle physicists don’t dismiss all of her concerns. “Without any doubt, Sabine touches upon issues that should be discussed,” said Van Riet. It’s the way they’re presented that may be damaging.

Priors

Hossenfelder has been rattling cages in physics for some time. She has questioned whether big particle colliders, like the one that may replace the Large Hadron Collider, should be built at all because we haven’t found these new particles scientists have been predicting for decades.

In January 2019, she authored an opinion piece in The New York Times, which suggested “the Large Hadron Collider has failed to deliver the exciting discoveries that scientists promised.” The LHC did help discover the Higgs boson in 2012 but hasn’t had any luck discovering other new particles. Still, others have argued it’s been a great success. 

In October 2020, she uploaded a YouTube video titled “Particle Physicists Continue Empty Promises” in response to a Nature commentary discussing how the field planned to move beyond the Large Hadron Collider experiment. In the opening minutes of that video, she declares “today I want to tell you how particle physicists are wasting your money.”

Other YouTube videos, stretching back to 2019, include “Have We Really Measured Gravitational Waves?” (we have, as Hossenfelder points out at the end of her video) and “Particle Physics Discoveries That Disappeared” (they didn’t disappear, as evidenced by the ability to make a video about them, but newer discoveries helped scientists move on to other experiments).

The controversial takes have often led to unjustified personal insults and harassment for Hossenfelder by other scientists. Those attacks are what led to her publishing the piece in the Guardian, according to her blog. I reached out to Hossenfelder for comment but did not receive a response.

Hossenfelder’s skepticism of scientific results and theories is absolutely warranted. Science is about refining our understanding over time as new results yield new insights. In this way, Hossenfelder’s critiques of particle physics can be helpful. But they’re delivered in a way that’s out of the ordinary for scientists. Debates don’t always rage on YouTube or Twitter or even in the opinion section of a major publication — they’re usually happening at scientific conferences and in the papers themselves.

“In science, it is the evidence that counts. Not opinions,” Hossenfelder states in her gravitational waves video. It’s unusual, then, to see Hossenfelder write an opinion piece in The Guardian, rehashing some of the old arguments she’s been making on her YouTube channel for years. The evidence shows progress is being made, albeit slowly, because theories are often decades ahead of experiments, just like they were for the Higgs boson.

It’s important for the field of particle physics to consider where resources are going and what projects are being funded. This process doesn’t happen in secret. In fact, in July, the particle physics community came together in Seattle for the Snowmass conference, a long-term planning exercise exploring the scientific opportunities for the next decade. 

“The emphasis is on community — everybody is welcome to participate — and on exploring the scientific opportunities for the coming decade,” noted Aida X. El-Khadra, a professor of physics at the University of Illinois. 

So what Hossenfelder is suggesting is correct: Particle physicists do need to take different approaches and conceive new strategies to move the field forward. The truth is the majority are trying to do just that. Conceiving new theories or particles may sometimes end in failure. That’s exactly how science is supposed to work. 

Bad aim

Hossenfelder’s piece paints the field of particle physics with one very broad brush, suggesting “thousands” of tenured professors are “ambulance chasing” and operating in secret, some sort of shady cabal that exists purely to continue existing and siphoning up research money. Particle physicists I spoke with disagreed with these generalizations. 

However, the practice of “ambulance chasing” Hossenfelder calls out in her piece is something that’s worth exploring. Ambulance chasing is the idea a new result or anomaly in particle physics inspires dozens of scientific papers trying to explain the result, sometimes invoking new particles or building out new models. This certainly does happen and is important to call it out, but it’s much less common than Hossenfelder suggests.

“Theorists certainly sometimes pick up experimental results with poor statistical significance, but it is not a big problem,” said Ulrik Egede, a particle physicist at Monash University in Australia. Egede points to the front page of arXiv, a server where scientists can drop preprint studies, and notes when he recently looked at the front page, only one in 25 would classify as a “theory we do not need.”

The truth is ambulance chasing is not just an issue in particle physics. It’s a broader problem with the way scientific research gets funded. Scientists typically acquire grant funding by convincing government bodies or philanthropic institutions they have an experiment or idea worth backing. One of the determining factors is their track record: Having papers under your belt goes a long way to convincing a funding body you deserve more funding. (If that sounds ridiculous, well, it is, as the Guardian itself pointed out in 2017.) 

This puts a lot of pressure on scientists to publish and particularly affects those early in their careers and from diverse backgrounds. As the funding for scientific research dwindles, as it has in places like Australia, that pressure grows. Scientists get caught in the cycle of publishing to stay in a job. They’re fighting each other to survive. 

This is something Hossenfelder herself has experience with. She tweeted in August that the German Research Foundation had knocked back her latest funding proposal. She mentions that several papers were not published quickly enough as being a potential reason for this. Publishing can mean more money. So, yes, some particle physicists might “ambulance chase.” So might biologists or astrophysicists or materials scientists. 

And focusing on issues like ambulance chasing misses larger, systemic issues in particle physics. It’s a field that suffers from problems similar to those in other STEM fields, particularly when it comes to diversity and inclusion. It erases the ability to have honest, open dialogue about whether we should build new, expensive particle colliders — one of Hossenfelder’s gripes. 

Why does this matter?

Forgive me if you’ve stumbled across previous CNET articles in which I say this, but good science communication and good science journalism is built on finding truth in uncertainty. It’s about preserving the nuances of a new study and conveying them honestly. 

The reality is that much of the public, myself included, aren’t familiar with the nuances and vagaries of particle physics and the challenges and problems beyond the Standard Model. We might not fully understand axions or wimps or, perhaps, even protons, neutrons and electrons. In this knowledge vacuum, we’re vulnerable to misinformation and hyperbole. It may not have been her intention, but Hossenfelder’s piece makes it seem as if the whistle has been blown: It’s not just the public that doesn’t understand particle physics, but the scientists themselves. That’s simply not true.

Penning opinion pieces “annihilating” entire fields and suggesting they’re operating secretively is a dangerous game to play. Not only does it erode trust in particle physics but in science as a whole. It gives the impression scientists are willingly scheming behind the scenes in an effort to get more money rather than answer fundamental questions about the universe or health or biology or climate. My experience over the last decade has taught me the vast majority of scientists are working insane hours for pretty pathetic pay because they’re driven to unlock the secrets of the tiny corner of the cosmos we occupy. 

Hossenfelder clearly has a great grasp of the concepts and can explain them in an engaging and interesting way. Don’t take it from me. Her YouTube channel has over half a million subscribers. She has real influence and can inspire positive change — she should be allowed to push back against the idea we need big, new, expensive particle colliders. She should be free to be skeptical. We all should learn from that.

But we should also be careful we don’t stifle curiosity. Theoretical physics pushes on the boundaries of everything we know at the very edge of our technological capabilities. That’s wild. In doing so, of course there are times scientists will be wrong. Of course there are times when their predictions or theoretical new particles don’t pan out in a way they expected. In fact, I’d say this is the norm. But a negative result is still a result. It does move the field forward, forcing us to rethink in search of a greater truth. 

Does the world need — want? — a new, expensive, mammoth particle collider to search for that truth? How much does it value the search for dark matter? Do we want to know the fundamental physics underpinning our reality? Those are questions worth asking; conversations worth having. But to push particle physics forward into a new and exciting realm, we should foster curiosity, spark new ideas, invent new particles when it makes sense and encourage new approaches when it does not.