The importance of strengthening the scientific culture

Based on an interview with Meghie Rodrigues. The version in Portuguese, from Ciência e Cultura vol.71 no.4, dec. 2019, is also in Meghie's post.

By Meghie Rodrigues

Francesco Vissani has easy laughter and good prose - which makes it seem that particle physics can be simpler than it really is. 

The Italian physicist, director of research at the National Laboratories of Gran Sasso of the Istituto Nazionale di Fisica Nucleare (INFN), is engaged in the study of neutrinos, subatomic particles that have no electric charge, almost no mass, and that interact little with matter - yet they are one of the most abundant particles in the universe.  

With a passion for scientific dissemination, Vissani is a member of the division for education, dissemination and heritage of the International Astronomical Union.

In 2014 he created the Asimov Prize for scientific dissemination, which involves students of Italian high schools. Every year, students choose the best scientific book published in the country - within a previous selection of five books, prepared by professors, scientists, journals and professionals from different areas engaged with scientific dissemination. Students vote the books and actively participate by writing reviews that explain their assessment - students who write the best reviews are asked to present the books at the award ceremony. (More info on that here.)

In his third visit to Brazil, Vissani is the first scientist invited to participate in the Cesar Lattes program of the Resident Scientist by the Institute of Advanced Studies (IdEA) of the State University of Campinas (Unicamp).

In an interview with Science & Culture he talks about nature and science, the interest in the study of neutrinos and the importance of scientific dissemination today.

Meghie Rodrigues: How neutrinos have been discovered and what is their function in nature?

Francesco Vissani: This particle was introduced in science in a funny manner. It all began with the Austrian physicist Wolfgang Pauli (renowned as the father of the theory electron spin), who was studying radioactivity - i.e., the disintegration of certain atomic nuclei.

At the beginning of the twentieth century, it was known that nuclei of certain elements apparently disintegrate without maintaining the energy they had - energy seemed to get lost. This is such a big thing that I want to rephrase it. When scientists measure the energy of the final fragments of the disintegration, they expect that it be the same originally present. But that does not happen for certain nuclei: sometimes more energy is observed, sometimes less - but always less than was originally present. 

This was a serious issue for a few decades, many people were puzzled about that, and Pauli was among them.

He thought - energy shouldn't be lost - so someone invisible should be taking the energy away. Thus, he concluded that what was being observed was due to "the action of some invisible, ghostly agent," even if he was not very happy with this hypothesis. 

But the stone had been launched, and slowly the scientific debate began to seriously consider Pauli's hypothesis. The idea was refined, and it was realised that the ghost particle should not have been exactly a ghost, otherwise it could not even be produced. A way to quantify its interaction with ordinary matter was found, some hints of the correctness of this position were found, and twenty years later the neutrino was actually observed.

Meghie Rodrigues: Can you expand the point? 

Francesco Vissani: Let us try! If neutrinos are really produced in this disintegration and do, let's say, their part, energy is not lost. It is only shared with these phantom particles. This hypothesis allows us to save the principle of "energy conservation" and allows us to predict new facts. This is how we got convinced that Pauli was largely right. 

Neutrinos have also some amount of rotation, that is similar (not exactly identical) to the spin of electrons. In general neutrinos are quite alike to electrons, e.g., they are not trapped in atomic nuclei, and moreover they have no electric charge.

They are absurdly tiny, even when compared to an atomic scale. 

If we zoom an atom till the size of our planet, its nucleus would be the size of a soccer field - and the neutrino would be the size of a virus. Because of this minuscule size, neutrinos cross matter almost without disturbance (or interaction with it) and it is very difficult to "catch it".

It is so difficult to detect neutrinos that you need many neutrinos to see only one and in addition you have to do it indirectly, seeing its effect on other particles, to finally conclude that one neutrino happened to be there.

One important example of the role of neutrinos is as follows: The center of the Sun, by melting hydrogen into helium, releases a huge lot of energy. The light of the Sun is one of the aftermath of these set of reactions. However, neutrinos are produced as well!

Therefore, by observing the neutrinos from the Sun we can monitor its engine.

We have seen the interior of the Sun with neutrino telescopes, just as we have been able to see the interior of our body with X-ray machines. With Borexino, a neutrino telescope that operates in the Laboratori Nazionali del Gran Sasso, we have been able to see practically all kinds of neutrinos of the Sun, and in this manner we monitor the reactions that happen in real time.

It is also possible to say that we see the elements that get transformed into others - just like in the dream of an alchemist - and release energy in the form of light and of neutrinos.

Meghie Rodrigues: Besides being a "ghost particle", the neutrino has already received other denominations, such as a "vampire particle". Why is that?

Francesco Vissani: It's a way of talking about some of the properties of this particle. Obviously, the name ghost is not because the neutrino died and came back to haunt us, nor because it barely passes through the walls as an ordinary ghost, but because it passes through the entire Sun - and all kinds of matter in fact - almost unscathed: This is a super ghost that takes vitamins :)

The reason it's called a vampire particle is just as curious. Electrons are free to rotate in opposite directions - for example, they rotate clockwise or counterclockwise, two configurations that are mirror images of each other. Neutrinos, on the other hand, do not work like that: they only rotate in one direction. Like vampires, they do not "have an image in the mirror", or rather, their mirror image does not exist in reality. This is the main reason why we call it a vampire particle. 

(The other reason is because it steals energy from other particles, just as ordinary vampires steal life. But I would not exaggerate with negative metaphors, at least, I have no reason to consider odious these tiny particles.)

They display more curious behaviours - and have gained still other nicknames accordingly.

The neutrino produced in the Sun appears when an electron disappears, and for this reason it is called electron-neutrino.

However, leaving the Sun and on the way to Earth, this type of neutrino has a well-defined chance to become another type of neutrinos, for example, a muon-neutrino - the one that is instead associated to a muon, a heavier cousin of the electron. This behaviour has been observed - in this sense it is a fact.

Thus, neutrinos are also called mutants particles.

This behaviour, predicted by Bruno Pontecorvo on theoretical ground, was actually observed, and its observation was recognized in 2015 with a Nobel Prize in Physics to Takaaki Kajita and Arthur McDonald, physicists from the universities of Tokyo, Japan, and Queen's, Kingston, Canada, respectively. (More words on this here, but this time in Italian.)

Meghie Rodrigues: What did we not know at the time of the Nobel, in 2015, what do we know now?

Francesco Vissani: First of all, it is important to say that this finding, the one that won the Nobel Prize in 2015, shows us that the best theory we have to explain the behaviour of particles, the standard model, is not a complete theory of nature. Actually, this observation is the only firm proof that the standard model be not a complete theory. (For further info on that, see here.)

Since then, we have been able to better understand phenomena that give us clues about the mass of neutrinos. And now we have also been able to see all the neutrinos that are being produced by the Sun, which expands our knowledge about them and about the Sun - as I have recounted just above.

There are also more advances in an area to which César Lattes himself contributed a lot. Lattes with Occhialini and Powell discovered the pions - unstable particles that are born from the collision of other high-energy particles, such as those present in cosmic rays. The pions decay and disintegrate spontaneously, producing neutrinos. 

This is something we have known for some time, but after one century, we still do not know where the cosmic rays come from. We hope that the neutrinos, that are produced almost inevitably together with cosmic rays, will offer us some clues about the origin of the cosmic rays.

There's an experiment at the South Pole - called The IceCube Neutrino Observatory - that is investigating this point right now. Apparently a new population of neutrinos has been seen and there are high hopes they are connected to the sites of production of cosmic rays, just through pion production.

Meghie Rodrigues: You have great involvement with scientific promotion and created the Asimov Award some years ago. What motivated the creation of the award and how has the process been?

Francesco Vissani: When a boy I used to read a lot about science (and SF and much more). I still think that books offer advantages over other media because they make you stop and think to absorb what's there. The sense of the Asimov Prize is to encourage students to try. 

Thousands of students from hundreds of Italian schools are taking part in it. The speeches at the award ceremony, given by the students with the best reviews, are surprisingly good and the participants are impressed by the thoughts of these young people (at the same time, the authors of the not so good reviews are very encouraged to do better). 

Not much money is involved in the award, even if - thanks to the support of various institutions, in particular Istituto Nazionale di Fisica Nucleare - we can pay for the trips and stay of the students, so that they can meet the author of the winning book at a science festival organised for this purpose, where they can spend some time together.

The author of the best book receives a symbolic award - a ceramic plaque with his image and the indication of the Asimov Prize edition. Rather simple minded, indeed.

The idea was inspired by a similar model from the Royal Society in the UK. After knowing this model I thought: "well, with little changes, it could work in Italy too!", then I decided to talk with some friends, then we decided to try it - and here we are.

Meghie Rodrigues: Talking about science and fighting misinformation these days are increasingly difficult tasks. Misinformation is always with us and we did not realise it? How can we talk about science in an emphatic way in the midst of so much polarization?

Francesco Vissani: I start from a distance.

The causes of diseases have been definitively clarified in the middle of the 19th-century. Now we can treat them, thanks to the knowledge we have collected by science. Maybe this looks obvious to modern readers, but, alas, it isn't.

Previously, when Galileo was founding the new science some persons were accused of diffusing plagues and therefore were sentenced to death for witchcraft - they were producing homemade soap, in fact, as it has been recounted by one great Italian writer, Alessandro Manzoni. It happened just in my country, Italy.

What do I mean? I mean that people do their best to react to the situations they perceive, but when it comes to understanding reality, or making a rational (political) decision, perception is not enough. One has to be sure that certain additional conditions be met:

1. You should have access to the relevant information.
2. (Which of course has to be sound and reliable.)
3. And on top of that, you should be inclined to debate and to exert critical thinking - which are very closely connected aspects.

If we consider this procedure from the point of view of the people, there will be someone who will find it tiring or too demanding. Nothing new! The Latin thinker Seneca used to say "people prefer to believe rather than judge" - and today perhaps he would have said "it's easier to click ?like? than to read and ponder". (Even Greeks use to the word ?δι?τη? - idi?tēs - for the people who refused to take part to the active life of the town - i.e., to politics.)

I am aware that there are still people who prefer to delegate their reasoning to others. However, many citizens all over the world want to think by themselves, and they do all they can to be able to draw their own conclusions. 

What is the role of scientists in this process? 

Let me begin with the critical views (Bacon would have spoken of pars destruens). Pretty surely, we should not report our results just to raise more money for research or to drop bombastic phrases that cause media frisson - that's really spoiling things for me. 

On the contrary, I think it is very important that we scientists communicate our findings as correctly as possible, so that people can decide what to think about these findings - and about us - on the basis of the best information available. This is an ethical issue, not small and not at all trivial.

Then, coming to a more specific point (and to the core of the pars construens) personally I think that, to better communicate science, we must keep our feet on the ground. We need to report what we are doing, not the daydreams of what we would like to do.

I feel that this is important for scientific communication but not only: It is vital also for the science and for us scientists. At least, this is what history tells us and what I strongly uphold.