Unlike in working with particle accelerators, where scientists plan their experiments in detail in advance, Patrik Čechvala has to wait and see what particles arrive from the depths of space. He is dedicated to observing particle showers caused by photons with extraordinary energies. In an interview about the MSCA COFUND Physics for Future postdoctoral program at the Institute of Physics of the Czech Academy of Sciences, he talks about why space is the best laboratory and how cosmic rays help uncover the secrets of the pyramids – as well as how to present the topic to the public in contests such as FameLab, in whose Czech finals he represented the Institute of Physics this year.
What fascinated you about astrophysics so that it became your life's work?
My interest in studying astronomy and astrophysics started in high school. That's when I decided to become an astronomer. Astronomy is about pushing the boundaries of the unknown, and when you combine it with particle physics, new possibilities for looking at the universe arise. This is what astroparticle physics is all about. I have been working in this field since my bachelor's thesis. While writing my thesis, I made my first contact with colleagues from the Institute of Physics who are involved in large international observatories, and now, thanks to the Physics for Future program, I can participate with them in an interesting project involving SST-1M Cherenkov telescopes located in Ondřejov at the Astronomical Institute of the Czech Academy of Sciences.
What do you focus on in your research?
My colleagues and I are involved in researching the universe at high energies, observing the most energetic parts of the electromagnetic spectrum – gamma radiation. While at the beginning of the last century, scientists were still researching the universe mainly using classic optical telescopes and observing primarily electromagnetic radiation in the visible range, recent technological developments have opened up new possibilities for us. Today, we can explore the universe using infrared radiation, radio waves, ultraviolet radiation, X-rays, and also other methods that do not rely on radiation – for almost ten years now, we have been able to detect gravitational waves.
However, particles also fly to us from space – nuclei of various elements, neutrinos, or protons. Scientists study high-energy photons from space using two types of methods: the first is measurement directly in space. But for now, we can only fit instruments of limited size into rockets, so we can only study photons up to a certain energy in space.
The second method involves using the atmosphere itself. The atmosphere is impermeable to such photons, but if they have sufficient energy, they create a shower of secondary particles in the atmosphere. We can record this using a system of ground-based detectors or by directly imaging the development of the shower in the atmosphere. During the propagation of the shower, so-called Cherenkov radiation is emitted. We can detect this bluish radiation with mirror telescopes equipped with a specialized camera, and from observing the development of the shower, we then try to deduce the direction and energy of the arrival of the primary photons from space. My colleagues and I are working on two such Cherenkov telescopes called Single-Mirror Small Size Telescope (SST-1M). This project was developed by research institutions in the Czech Republic, Poland, and Switzerland.
The system of two telescopes with a primary mirror diameter of four meters is located at the observatory of the Astronomical Institute of the Academy of Sciences in Ondřejov. We observe showers in stereo mode, as this allows us to more effectively reconstruct the direction of arrival of the primary photon, estimate its energy, and distinguish between showers caused by gamma photons and those caused by protons.
What does your workday look like?
As part of the project, I am responsible for working with simulations. We need to specify how sensitive the telescopes are, what their angular and energy resolution is, and how effectively we can use them to distinguish between showers caused by gamma photons and those caused by protons. We are currently considering two future locations, and one of my tasks is to prepare a detailed analysis of these parameters for the possible new location of the SST-1M telescopes and their optimal distance. So, I mainly work with computers, programming and processing simulation results. In addition, I also help my colleagues with observations on telescopes. Therefore, my working day is quite varied!
Astroparticle physics began to develop in the early 20th century, but then scientists created the first accelerators and its popularity faded into the background. Why have researchers been returning to it in recent decades?
For physicists, it is important to have a controlled environment where they can choose the parameters and have clearly defined conditions for their experiments. In astroparticle physics, we are dependent on what the universe itself sends us, and that was one of the reasons why scientists' attention turned to accelerators at a certain point in time.
The universe occasionally sends us particles with energies far higher than we can generate in an accelerator. Protons or nuclei of the highest-energy elements strike the atmosphere only once every hundred years per square kilometer. In addition, gamma rays, neutrinos, and gravitational waves also come to us from space, and if we detect the source or event in space through these "messengers from space" simultaneously, it is possible to obtain a more comprehensive picture of the properties of various exotic sources and the high-energy processes that take place in their vicinity. This technique is also called multimessenger astronomy.
Specific observatories are being built to effectively detect individual types of "messengers". One of the methods these observatories use is to build large arrays of ground-based detectors spread over a large area to capture as many showers as possible.
Since no single institution is capable of building such observatories, they are joining forces in large international consortia, such as the Cherenkov Telescope Array Observatory (CTAO). This observatory will study gamma radiation and will consist of dozens of imaging Cherenkov telescopes. SST-1M was developed as one of the types of telescopes for CTAO, but it is currently a separate project, where we are completing the testing phase and obtaining the first scientific results.
Can the method have any practical use, or is it purely basic research?
That's a good question – people usually say "just basic research," but the reality is different. Some methods based on knowledge of astroparticle physics have found application in completely unexpected fields. Cosmic ray muon tomography is used in archaeology, construction, and geology. Muons have the ability to penetrate material much deeper, which allows us to study places that we cannot otherwise see. Louis Alvarez placed a muon detector in one of the lower chambers of the Rachef Pyramid in Giza as early as the 1960s. More successful was a project by scientists from Egypt, Japan, and France, which used muons to image the internal structure of the Pyramid of Cheops. In 2017, they discovered a new 30-meter-long cavity in the pyramid. In Japan, the muon method helped to find out what was happening inside a volcano and the damaged nuclear power plant in Fukushima.
By the way, how did you get involved in the Physics for Future program?
I applied, went through the selection process, and maybe I was a little lucky. I got two great supervisors – both named Jakub, one is Vícha and the other is Juryšek by last name. They are leaders in their field and excellent mentors. We had worked together in the past, and they told me about the opportunity to apply for this program, which I was happy to take advantage of. I think their approach – a combination of creativity, precision, and openness – has helped me advance a lot professionally. In addition, the program offers training not only in science but also in soft skills – such as how to write a project, plan a career, or communicate science to the public. That's crucial these days.
You have extensive experience in popularizing science. Could you tell us your favorite way of doing so?
Astronomy has the advantage of naturally attracting people to a certain extent. Stars, black holes, and the entire universe are profound and powerful topics that spark curiosity. It is only natural that my colleagues and I are involved in this activity, because it is extremely necessary in today's world.
I personally started popularizing astronomy in high school when I worked as a lecturer at the Natural History Museum in Bratislava. I explained the exhibition on astrophysics, as well as interactive exhibits, in a way that was entertaining for both children and adults, which forced me to learn how to talk about science in an understandable way.
Since then, I have been helping and participating in a number of activities – together with amateur astronomers from Bratislava, we are trying to popularize astronomy and topics related to space exploration by organizing public observations, workshops, and public lectures as part of a civic association. For more than ten years, I have been helping to organize a regular series of popular science lectures at the Natural History Museum in Bratislava, and for five years I also led an astronomy club for children there.
My colleagues and I are trying to build a planetarium in Bratislava, which we have been lacking for a long time. In this respect, the capital of Slovakia can only envy Prague. Recently, however, we achieved a great success when my colleagues and I participated in organizing the construction of an observatory on the roof of the German School in Bratislava (Deutsche Schule Bratislava). It was built thanks to a collection of parents and friends of the school. When my colleagues and I looked into the archives, we found that it has been approximately 40 years since the city last had an observatory open to the public. The school also initiated astronomy clubs. I am currently still trying to help this project remotely by providing consultations and creating an observation program. The observatory has high-quality equipment, and I would like to see student projects developed here, with students achieving interesting results and gaining experience with astronomical technology.
I also give lectures on topics that at first glance one would not expect to be related to astronomy or physics. In this spirit, a series of lectures on physics in the kitchen or astronomy in the books of J. R. R. Tolkien was created, and some of them have been published as popular science articles. Scientific cooking was even featured throughout the year in a special section of a Slovak popular science monthly magazine. I also regularly participate in science festivals, or try to "smuggle" scientific topics into pop culture festivals.
This year, you also became a finalist in the prestigious FameLab popularization contest, in which participants have only three minutes to present their scientific topic. What was that experience like? Will you use it in some way in the future, or are you planning to participate in other competitions such as Falling Walls?
Participating in the FameLab finals was an amazing experience for me. It is a format in which scientists are forced to explain their research topic to the lay public in a short period of time in an engaging way. In addition to the content, they must also pay attention to the form of their presentation. I speak mainly for myself, but I assume that the other contestants had a similar experience. It was necessary to push ourselves, step out of our comfort zone, and work on our presentation, performance, and even acting, which can be a bit of an atypical position for scientists. In this respect, I think it's a great experience. It's also very nice to see how the whole FameLab community works and interacts, even outside the competition itself. I would like to thank the organizers for the opportunity to participate in something like this. A big thank you also goes to my colleagues at FZU for being willing to sacrifice part of their lunch breaks in September to listen to me practice for the finals and give me feedback. I think the concept of communicating science in this way is very interesting. In the past, I had the opportunity to participate in a similar event in French organized by the French Institutes. I would very much like to use these experiences in the future and am considering participating in Falling Walls.
How do you relax outside of work?
When I manage to find some free time, I like to spend it doing some kind of physical or outdoor activity. I try to go to the gym at least once a week, and I enjoy ballroom dancing. I have fond memories of dancing from a mechanics exam at university, when we were given the task of calculating the momentum of a couple dancing the waltz and had to estimate individual variables such as the weight of the male and female partners, their distance from each other, and their speed of rotation. I began my answer by considering the differences between the English waltz and the Viennese waltz. I concluded that we would consider the Viennese waltz, for which I also made an approximate estimate of the angular velocity so that it corresponded to a proper waltz, and then added the angular momentum.
In Prague, however, I miss my best companion for trips and walks in the woods, my dog Andy. He enjoys the large gardens at my parents' house in Slovakia, so he is happy. Speaking of gardens, I must also confess my love of gardening and cooking. I also regularly meet with friends to play board games.
What do you enjoy most about scientific work?
It's the combination – scientific curiosity, international cooperation, the effort to understand something that is completely beyond our normal understanding, and also the fact that we learn to be patient – we are dependent on what nature sends us, but it's good to be prepared for news from the depths of space.