Sabine Hossenfelder (No one in physics dare say it, but the race to invent new particles is pointless, September 26) has missed a lot of particle physics, even fundamental research in general. While we would all love to revolutionize our respective fields by discovering some new particle or the like, in reality eliminating the impossible – particles that don’t exist – is an equally important, albeit laborious, function of science. Nature has an infinite capacity to surprise, and our scientific ancestors long ago learned not to take anything for granted. Each proven impossibility brings us closer to a deeper understanding of the real universe; it is just as important to know that it is impossible to travel faster than light as to understand that light is composed of photons, for example.
It would of course be extremely tedious to rule out all outlandish possibilities (Hossenfelder’s octopuses on Mars, for example), and so we need a set of principles to guide us on where to look. There is general disagreement over what works best, but many of the hypothetical particles mentioned in the article were designed with useful functions in mind – breaking cherished principles of the Standard Model for example, or adding to them new features. What we test are the principles themselves, not the particles; while some of them might actually exist, others are just straw men to help us formulate useful tests.
Dr. Phil Bull
Reader in Cosmology, Jodrell Bank Center for Astrophysics
Sabine Hossenfelder argues that particle physicists are far too eager to speculate on new particles, suggesting this is done for reasons of professional advancement, rather than a sincere desire to advance our understanding of the universe. In fact, we develop and propose new theories and new particles because there are real puzzles and open questions that our current best theory, the Standard Model, cannot solve. This is how science is supposed to work.
The neutron was proposed in 1920 and discovered a dozen years later. Likewise, positrons, pions, neutrinos, quarks, etc. were all hypothesized by physicists long before they were observed in an experiment. More recently, the Higgs boson was discovered in 2012, having been proposed half a century earlier. I wonder how many of these discoveries would never have been made if physicists had followed Hossenfelder’s advice on their approach to science.
Hossenfelder’s assertion that the standard model “works just fine as it is” is simply not true. The Standard Model predicts that neutrinos should be massless (they are not), that the neutron’s electric dipole moment should be large (it is undetectably small), and that there should be equal abundances of matter and antimatter in our universe (there is none). Moreover, most of the matter in our universe is made up of dark matter, which is not described by the Standard Model. These are not hallmarks of a theory that “works just fine as it is”.
Of course, most of the particles that my colleagues and I speculate about won’t turn out to be real, and that’s fine. Nor would anyone expect every suspect in a criminal case to ultimately be found guilty. The purpose of these surveys is not to be right all the time. Instead, it’s about rationally considering the possibilities, studying their consequences, deciding what experiments to build and perform, and ultimately learning as much as possible about our universe.
Professor of Astronomy and Astrophysics, University of Chicago
Particle physics is about more than just inventing and searching for new particles, or “bump chasing” as we call it. The Large Hadron Collider (LHC) was built with two main goals: to find the Higgs boson, predicted by the standard model of particle physics, and to search for new phenomena needed to explain some of the fascinating details of our universe for which we currently have no explanation, such as dark matter.
There is no good model to guide us where to look for empirical evidence, just lots of theories, some predicting new particles. We grope in the dark, looking for evidence to send us in a new direction. Part of that is bump hunting and, as Sabine Hossenfelder rightly pointed out, this method did not yield any new findings and is less likely to do so now because many possibilities have been ruled out. But the unknowns are still there and the universe is once again revealed to be subtle and mysterious. What we are doing now at CERN’s LHC is making increasingly precise measurements with the data we have, looking for small deviations from the Standard Model to guide us to where we should be looking for new phenomena. .
There are many analogies in the history of science for this process – Albert Einstein tweaking Isaac Newton some 250 years after the Principia, and more recently the Cern LEP machine, a precursor to the LHC, finding anomalies that have guided us where to look. the Higgs boson. Just because there aren’t fruits within reach doesn’t mean there aren’t fruits to be found.
Professor of Physics, University of Minnesota
As a professional astronomer, I fully share Sabine Hossenfelder’s point of view on physics. Unfortunately, the situation is no different in today’s astrophysics, which is filled with useless papers on the properties of dark matter and dark energy, on which countless brilliant careers have been built.
As in the case of physicists, in private many astrophysicists would question the existence of these entities, even if no one openly states it (let alone writes it down in a paper). The situation is ridiculous to say the least.
Any voices contrary to traditional astrophysics are effectively drowned out by the arbitration system, which ensures that only orthodox results appear in technical journals. The James Webb Space Telescope will most likely provide enough evidence to change the status quo, with important consequences for fundamental physics.
Dr. Ricardo Scarpa
Brena Baja, La Palma, Spain
Sabine Hossenfelder provides valuable insight into how the mechanical application of mathematics can be falsifiable, pass peer review, and meet funding requirements. But its central point, that there is little point in theories that are falsifiable but unverifiable, has broader lessons.
Think tanks and institutes have generated many social and economic theories and, as with particle physics, there is no shortage of well-researched, peer-reviewed and well-funded ideas to inform government, business and private policy. Like dark matter and dark energy, inequality, poverty and lack of opportunity can be measured, analyzed and theorized from all angles. But does this intellectual production improve things in proportion to the effort provided? Many think not.
More insight and less rote ideology is the call. Notice to economists and social theorists.
St Albans, Hertfordshire