A new discovery in physics tells about democracy in science
As a scientist, sometimes I wonder: is there democracy in science? Sure enough, anybody can express their own opinions. However, when a new result or a new discovery is presented to the scientific community, it’s the mathematical rigour or the experimental accuracy that ultimately tells if the new result is correct or not. The new result needs to be accepted by the community, that’s true, so there is a human and social touch to it. However, the process is far from being democratic. I want to draw a parallel between politics (and democracy) and the way science works in this situation. First, let me give you a taste of how the science works in the next few paragraphs.
On April 7, 2021 the scientists at Fermilab announced a new, very precise measurement of the properties of one particle. This result confirms a previous experiment done 20 years back. However, there are two predictions for this property: one suggesting that our current understanding of physics is incomplete, the other suggesting the exact contrary. How does the scientific community choose between the two?
What a team of scientists measured at Fermilab is a property that the particle called muon reveals when passing through an intense magnetic field. The muon is a big brother of the electron, much heavier and with a fickle nature that makes it short-lived. We can picture the muon as a spinning top. When moving near a powerful magnet, it will start swirling around. The stronger is the magnet, the faster it swirls. Physicists measure this property with a number, traditionally called “g” or the muon magnetic moment, which Paul Dirac first predicted to be equal to 2. And it was soon measured to this value. Done? Not so fast.
As Italians say, “non dire gatto se non ce l’hai nel sacco”, don’t say “cat!” if it’s not in your bag. Definitely true when it’s the Schödinger’s cat that we are chasing! Quantum physics, in fact, predicts that a swirling muon will summon into existence particles out of the vacuum, and their presence forms a cloud around the muon that changes the value of “g” by a tiny little bit. Particles of light, for instance, contribute two parts in a thousand. This effect is purely due to quantum physics. All particles contribute, including the ones that we may not have discovered yet. Hence, measuring “g” with the highest possible precision can reveal the presence of new particles beyond our current knowledge.
Experimental physicists took this task very seriously: in 2000, an experiment in Brookhaven, US, measured “g” of the muon with a precision of less than one part in a billion. To give you a scale, this precision amounts to counting all wheat grains produced in Arkansas in 2019, without missing a single one! This is an amazing achievement, however, it was not enough to convince the whole physics community. In science, a second experiment is needed to confirm the result, even when there is little to no doubt about the work done. So, a second team of scientists formed and designed a new experiment at Fermilab, which revealed their first result on April 7, 2021. Analysing only a small part of the data, they measured “g” again with a similar precision as Brookhaven achieved, and found a very similar value. Thus, the result seems to be confirmed, and the Fermilab team will continue collecting and analysing data to further increase the precision. As you can see here, it’s not the opinion of the community to decide if the result of the first experiment is correct, but a second independent experiment obtaining the same.
The first result from Brookhaven in 2000 also launched a big challenge to the theoretical community: their task, at that stage, was to predict the value of “g” from quantum physics, including all the known particles (collectively called the Standard Model). There is an obstacle, though: quarks. They are particles that are continuously glued to each other, so it’s impossible to see them individually. Thus, the swirling muon cannot summon into existence individual quarks, but a muck formed of many quarks glued together by glue-particles (gluons). Theorists had to scratch their heads bald to figure out how to calculate this with precision matching the experimental result!
There are two ways. The most accurate one relies on measuring at experiments how the quark muck itself interacts with a magnetic field. These results can be translated into the muon “g” by use of a clean mathematical procedure. After many years of efforts, the due precision has been achieved, with the result that the theoretical value does not agree with the experimental one. This mismatch may reveal the presence of new unknown particles, thus opening a new page in the history of physics! How do we know for sure? Certainly not by a vote in the scientific community!
The second way relies on precise calculations done on super-computers, without relying on experimental data. Until now, the precision of these computations was far from enough. The plot thickens, however, as on April 7, 2021, while Fermilab was announcing their experimental result, an article appeared in Nature presenting new results of a super-computer calculation, achieving a precision close to the experimental one. This time the result is… right in between the experimental one and the other Standard Model calculation. If the new calculation is correct, then there is no need for new particles beyond the known ones of the Standard Model. In the community, there is no consensus, and I have to confess I would not know which option to choose, if I were asked to vote. Fortunately, science is not based on votes but on independent confirmations. If the new result is correct, other teams of scientists should be able to obtain the same with independent techniques. And then, re-examine the previous results to understand why they differ.
If you are still reading the article at this point, you should have a taste of how science works. The situation with the muon “g” is typical, and marks all scientific progresses. Anybody can challenge the current and accepted knowledge, but only with solid and reproducible results. It means that other teams of scientists should be able to obtain the same results, or at least compatible ones, with different techniques. Only once this stage is passed, a new discovery can be confirmed. The most popular “belief” does not matter here! In politics, on the contrary, it’s the popular vote that often has the strongest weight. Think of Brexit in the UK, which has happened only because of the outcome of a popular vote. Many decisions in politics could be better taken following evidence and rigorous thinking, like it is done in science. Opinions should be based on evidence, data, and clear understanding of the social and economic situation of the country. Is voters’ opinion really enough to decide if an action is correct and beneficial for a nation? I believe that democracy can be improved by learning from other disciplines.
