Tuesday, June 20, 2017

Overbye on "ominous silence" in particle physics

Dennis Overbye is a top science writer and his new text in the New York Times,
Yearning for New Physics at CERN, in a Post-Higgs Way
is also pretty good. He quotes various particle physicists, including fans of SUSY and critics of SUSY, and those give him different ideas about the probability that new physics is going to be observed in coming years, but he decides to make a conclusion in one direction, anyway: the silence in particle physics is ominous, the subtitle says.

In particular, Overbye talks about the silence after the \(750\GeV\) hint faded away. It's been just a year or so when this bump disappeared. Should one be using ominous words such as "ominous" when there has been no similar intense wave of activity for a year? I don't think so.

There are at least three problems that I have with similar statements about frustration, depression, confusion, and ominous signs in particle physics of recent years:
  • it is irrational to single out the present
  • the success of the existing effective theory should not be described as "confusion" but the opposite of it, the lack of confusions
  • in general, it is irrational to link one's mood to the success of older or newer theories
What do I mean?

First, it's silly to say that 2017 is particularly frustrating because no new particles have appeared. The known list of elementary particles has really been settled in the mid 1970s or so. It became clear in that decade that there had to be three generations of quarks and leptons, gluons, photons, W-bosons, and Z-bosons, and the Higgs. Most of them were already discovered in that decade. An anomalous particle was the top quark that could have been lighter but it wasn't and was discovered in 1995; and the Higgs boson whose existence was obvious from the 1960s but that was only discovered in 2012, for some reasons.

So the absence of new elementary particles that are forced on us by experiments or indisputable arguments in theory isn't a new phenomenon. It's been the default state in some 40 years – and in many previous long periods, too. In particular, I haven't really seen a paradigm shift that would add a new particle to our list – I mean the unquestionably demonstrated list – in my whole life. So I just don't understand the calls for frustration. If people like me should be frustrated by the null results, our whole lives should be frustrating. Well, it may surely be said to be true from some viewpoints ;-) but it doesn't have to be. One may adopt a neutral or optimistic psychological attitude, too.

The choice of the "bad mood" is unjustifiable. The "bad mood" isn't science, it's just some emotions. As a Czech guy interested in politics, I can't resist to mention that the first president of modern Czechia Václav Havel began to talk about the "bad mood" ("blbá nálada") in the society starting from a talk he gave in 1997, i.e. exactly two decades ago. The problem was that these complaints about the political situation weren't an impartial, rational analysis in any sense. Instead, it was a political campaign because he was really promoting the bad mood.

But the word "confusing" is even more wrong. When the Standard Model works perfectly, there is no real confusion when it comes to predictions of particle physics experiments – and predictions are what science is almost all about. What does it mean to be confused? Yes, the Standard Model cannot be a complete theory and its parameters look fine-tuned or unnatural according to some basic guesses about "what should be beyond the Standard Model". But this observation is basically equivalent to the statement that we don't have a complete and completely proven theory of everything yet. Without such a theory, you just can't reliably determine the probability that some coupling constants are large or small etc.

We have never had a complete and completely proven theory of everything yet, however! So if the confusion we talk about is equivalent to the absence or incomplete status of our TOE, it's the minimum confusion that has always existed in science. The word "confusing" is just self-evidently wrong. I feel like Sheldon who is correcting Penny when she says that something is typical. On the contrary, it's an almost textbook example of something that is atypical, Sheldon once correctly pointed out!

But perhaps most importantly, I think that this whole identification of "good mood in physics" and even "the likability of physics in the public" with the "rate at which paradigms are shifting" is utterly irrational, too. As long as people are impartial about their expectations, there shouldn't exist any correlation like that. In fact, around the year 1900, the correlations that were used to say bad things about physics were upside down.

The period around 1900 was said to be a "frustrating period in physics" exactly because the framework of classical physics that had been established as well as the Standard Model (and GR) is established today ceased to work well. And indeed, it was fashionable to talk badly about physics than a few decades earlier. But with hindsight, the years around 1900 seem hugely important and with some emotions, absolutely wonderful. Various manifestations of radioactivity, X-rays, ionizing radiation composed of elementary particles were discovered. And in 1900, Planck figured out how to calculate the black body curve assuming that the energy of the electromagnetic radiation was quantized. First steps towards quantum mechanics were made. And in 1905, Einstein had his miraculous year. Relativity was found, the atomic theory was settled thanks to the new theory of the Brownian motion, the theory of the photoelectric effect has increased the seriousness of the photons, and so on.

Physics was getting "bad press" because the old picture of physics didn't seem sufficient. These days, physics is getting "bad press" because the old picture of physics seems very sufficient. These biases are opposite to each other. Both of these biases are just wrong in physics – and in science. Physics and science have the purpose of understanding Nature as correctly, accurately, and deeply as possible. Some theories or ideas may have a very wide range of validity. If it is shown that it is the case, it is how Nature works. Some theories break down. When they do, it's also wonderful, we're learning about a new thing and we have to pick the right replacements.

But it is not the goal of physics or science to maximize the frequency of paradigm shift or make a Trotskyist permanent revolution. In the same way, it is not the goal of physics or science to fanatically preserve some old ideas. It seems that the people – journalists, laymen, but also some physicists who basically cooperate with them – are introducing these utterly irrational biases. But these biases don't define science. They define ideologies such as Trotskyism or the Inquisition. If you do physics well, you look for the relevant evidence, arguments, and calculations that allow you to find correct answers, predictions, and explanations of wide and interesting sets of physical phenomena.

The correct answers may look more conservative or quickly evolving but the quality isn't measured by this speed of revolution – with either sign. The quality is measured by the correctness, accuracy, and universality of the predictions and the consistency, coherence, elegance, simplicity, and unified spirit of the theories that are used to make these predictions. The Standard Model may work up to proton-proton collisions at up to \(13\TeV\) or \(1,300\TeV\). We don't know the answer. None of these answers should bring bad press to the scientific research. It was Nature who decided about the answer and before we know this answer, we have the duty to be impartial towards the possible options. If the Standard Model works up to \(1,300\TeV\), then it is how Nature works. It means that most of the science, when done correctly, will obviously focus on other questions than the same experiments at slightly higher energies in coming centuries.

It is a strategy to work on the progress in physics by doing similar experiments and increasing the energy and luminosity gradually. I still think it's the most sensible strategy to do truly experimental particle physics. But the truly experimental approach just isn't the only one. Theorists are also learning about the coherent logic underlying particle physics by employing characteristically theoretical approaches. There's nothing wrong about them. Many of these ideas are absolutely wonderful. It remains to be seen which of the strategies and ideas will gain the importance in the next 10 or 50 years. Whatever the answer is, physics may be done correctly and cleverly, be wonderful, and deserve good press.

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