Interview with Nuclear Astrophysicist Thanassis Psaltis


I met Thanassis recently at SciArt's Bridge residency where we were paired to produce a scifi project involving nuclear astrophysics and a dome projection. To better define our collaboration and inspire ideas I conducted a thorough interview with Thanassis. We spoke about many interesting aspects of his current research and compared similarities in our interests, essential for future collaboration. I enjoy Thanassis' philosophical approach to fundamental research and the way how he positions his research concerning philosophy and historical influences of the evolution of scientific worldview.

T: I am sure that all of us once starred at the night sky, and felt lonely and meaningless under the vastness and complexity of the universe. In a particular way, my research is trying to subvert this feeling and instead is seeking to highlight our intimate connection to the universe. We are a living part of it. Figuratively, you are a way for the universe to know itself. Everything made out of matter is made of atoms, including nature and ourselves. Atoms come in a wide variety of classes and are classified into the periodic table with about 100 elements. The whole universe is composed of these elements. If the entire universe would be a book, we could say that it is written in an alphabet of one hundred letters. Another fascinating thing is that between us and the universe there is not a real difference because we are primarily made of the same stuff. A human being is a large group of atoms with a mission to develop an understanding of how the universe works. Atoms in our bodies came together in such context that we can think about the universe, why it is here, how did it evolve. Scientists are like “psychotherapists” of the universe. (hahaha)

M: It is very intriguing that this way the universe is able actually to observe itself. What do you think about the role of general intelligence in the universe, consciousness and fine-tuning of the universe to sustain life?

T: I do not have a very robust opinion on that. Amongst the whole variety of published views, there is one particularly interesting idea, which I do not fully believe at the moment. If we assume that quantum mechanics does work in the universe, even the smallest constituents of matter, atoms have their consciousness. But that is a bit radical idea, and I have to look more into that. I do not fully embrace it. (hahaha)

M: I was more thinking about the Boltzmann’s brain paradox. If you give atoms infinite amount of time in space, because of random recombination, they could eventually form an “accidental brain.” Mathematically speaking, if there is an infinite amount of time, there is an infinite number of positions and shapes the atoms can take.

T: Yes there is the whole thing about alternative universes or multiverse which is very controversial in our field. It is almost split opinion. Half of the scientists believe in it, and the other half does not.

M: Where are you on that spectrum?

T: I am more inclined to believe in the multiverse, but I am closer to the middle right now. Eventually, as a physicist, I would have to take one or the other position. There is no middle ground.

M: This is very interesting. In a rigorous science, there is a point that you actually have to take a position?

T: Some of these things are more philosophical than the rest of the physics. You have to first take the position philosophically, on how you interpret quantum mechanics, and then you continue researching it.  

M: how would you describe the experiment you are working on currently?

T: Beyond the simplest elements such as hydrogen and helium, the rest of the elements are created in astrophysical environments. The lives of the stars determine the origin of the elements in the solar system, in the galaxy, and ultimately in the whole universe. Me, as an experimentalist, I am trying to recreate some of the reactions, that we believe are happening inside astrophysical environments. From these results, we are seeking to retrieve data that will help theorists to predict the abundance of the elements in our solar system. In the current experiments, we are studying the heavy elements. Heavy elements are the elements heavier than Iron - which is one of the most bound isotopes in the universe. The reaction I am studying is supposed to change the outcome of nucleosynthesis and eventually the abundance of the heavy elements in the solar system. Instead of directly creating heavy elements we produce lower mass elements. By recreating a reaction like this, we can get an estimate on how fast such reactions happen inside the stars. By retrieving information about this process, we can input the values into a model which eventually also creates the heavy elements. We are observing how their abundance and production changes in the model. Our part, as experimentalists, is to give the theorist the numbers and they do the rest of the job.


The Dragon facility

is part of the TRIUMF, Canada's national laboratory for particle and nuclear physics and accelerator-based science.

Dragon is the facility where Thanassis conducts his experiments.

M: So, “We are all made of star stuff?”

T: It was a brilliant phrase that had a substantial impact. Our bodies are made of elements that come from the stars, as I mentioned previously. Except for hydrogen. But hydrogen is, in a way more exciting because it was created three minutes after the Big Bang. We have stuff which is almost 14 billion years old and some other stuff that was created just a few billion years ago inside a massive red star. All of that is right now inside of you.  

M: There are many different kinds of stars. Do all of these various types produce various elements? Do particular stars create specific elements?

T: If you consider the initial mass of the star, we know exactly how it will evolve and how much of each element it will produce. Things get interesting if you bring another star to the party. For example, a combination of a star like our sun and a white dwarf. In such case, the white dwarf has a powerful gravitational field, and it will start pulling material from the other star. At some point, after a limit is reached, there will be an explosion. It is called a classical nova. This happens quite frequently, almost ten per year in our galaxy. In case there is a combination of a sun-like star and a neutron star, we have the so-called x-ray bursts. Different stars create various elements.  

M: What is the future of research in your field?

T: During the last fifteen years our area has started to accelerate. Right now, we are in an era where we are building new laboratories that can produce even more exotic nuclei than the ones we have right now. In five to ten years the construction of these giant laboratories will be finished, and we will have much more access to this exotic matter.  

M: how different is the cyclotron at your research center from CERN?

T: A cyclotron accelerates charged particles in a spiral orbit. Magnets accelerate an ion from a small radius by incrementally changing the magnetic field and expanding the orbit. With each increment, the energy of the particle grows until it reaches the particular level needed for the experiment. The CERN is a synchrotron, which is a different instrument. You don’t have a spiral movement, just a circular orbit. CERN does not only have the large hadron collider, but this machine is also connected to smaller ones that accelerate the proton before it enters the large chamber. It can reach vast amounts of energy, eight Teraelectron-volts or so. This is almost six orders of magnitude higher (1 million) compared with what we need for our experiments.  

The most anticipated instrument is being built right now in Michigan and is called Facility for Rare Isotope Beams (FRIB). It will be finished in a few years. Also, some of the older labs are currently upgrading.  



Similarly to Dragon, the cyclotron is also part of the TRIUMF

M: What do you expect will be discovered?  

T: That is the fun of it. You are expecting something new, but you do not know what it will be! For example, oddly, I would be happier if the Higgs boson wouldn’t be discovered. In that case, scientists would have to develop new theories. The standard model is cool but finding the unexpected is always more fun. There are some issues with the standard model. For example, according to the theory, neutrinos do not have mass, but it was discovered that they actually do have a minimal mass. So there is something beyond the standard model, but that is an entirely different area of research. I am not involved in that, but I know it is pretty exciting.  

M: What are your favorite science fiction movies?

T: Once I made a planetarium show about the science of Star Wars. The show was divided into six chapters with six different sections of physics. There was exoplanets, aliens, robots and AI, space battles and light speed, the science of the Death Star, the concept of the Force and lightsabers.  

M: What do you think about science fiction?

T: Science fiction is a way for art to get science to the public. You might not know about nuclear physics or astrophysics, but you have watched Star Wars and Star Trek, and you think it is cool! One of the reasons I went into the science was that I was a huge fan of Star Wars and Carl Sagan. By doing something that is science fiction is an excellent way to get the message through and get people involved in what we do. My research is not really connected to the society. You will not use my research to create something that will make your life easier. It’s not like nuclear energy for example. However, this fundamental research is more important because it answers some questions about the origin of the universe and humans. It is more about profound questions that elevate your spirit. That is something we really need in this era. We are so consumed in the mechanistic way of thinking. We are very much into machines and how they work, and we have to be very exact. We should also think more abstract than that, to connect more with the universe. Right now we are not. The whole society is very individualistic and disconnected.

Fundamental research is essential for other, more "applied" types of science. Most of the other sciences, like biology or chemistry, are based on seventeenth-century physics. Newton, Leibnitz, and Descartes. All of these deterministic ideas were implemented in these sciences. However, it has been almost 100 years today that we know this is not the most exact way to describe nature. We are aware that nature has a different way to behave in the small-scale, quantum mechanics, and we know that in high speeds we have Einstein’s relativity. Things are not quite like the sixteenth, and seventeenth-century thinking prescribes. For four hundred years we have not changed our mind in that matter.

I am also really interested in quantum biology because they are studying principles of quantum mechanics implemented in biological systems.  

M: You mentioned that hydrogen was created about three minutes after the Big Bang. How about the other elements?  

T: Apart from the hydrogen created 14.6 billion years ago, and some of the Helium which was formed at about the same time, for all the other stuff we cannot really tell. We can have for example some giant red stars that created some of the carbon in our bodies, but these red stars might have been created four point six billion years ago or earlier. What we can tell with certainty right now is that all the other elements in our bodies were made at least four billion years ago because that’s when our solar system was created. So everything is four billion years old and older. We cannot tell when, but we can say in what environment. However, some elements can be created in more than one environment.  

M: Can we tell what was their “address” they were created at?

T: We know that the heavy elements, meaning heavier than iron, are mostly synthesized in supernovae explosions. They determine the end of life of a star. For example gold. Carbon can be produced in many stars, including our Sun or more massive stars. Sun is fusing hydrogen into helium for another five billion years. After that, it will become a massive ball of helium, and its core will subtract because of gravity and then it will start to burn helium. Then helium will be burned into carbon. The sun at that time will become a red giant. The core will be very dense and small, but the atmosphere will keep expanding until it reaches very close to our planet. Some simulations suggest that it will even cover the earth.  

M: In the history of our solar system, was there a lot of transfer of the elements from the outside of the solar system or was all the matter in one location, one cloud, that later formed into the system?

T: Many theories suggest that comets brought the first material into the younger earth and that started the life as we know it, but the whole thing is very complicated. I am sure there was some interaction between the newborn solar system and the outer region.  

M: If there was a "detective" who wants to figure out where these elements came from, where should he or she start?

T: The best choice, in my opinion, would be first to investigate the massive stars. There is a theory that the beginning of our solar system was caused by a nearby supernova explosion. This explosion made our interstellar medium to collapse into a protostar which later became our sun, and the other stuff, that surrounded the sun became our solar system.  

M: What is a protostar?

T: It is an “embryo” star. It is not a real "hot star." Instead, it is a very dense cloud, mostly hydrogen. A protostar compresses because of gravity and heats up. When it reaches a critical temperature, around fifteen million degrees, hydrogen starts to fuse into helium. The beginning of nuclear fusion is the year zero, the birth of the star.  

M: have you ever heard about a Dyson sphere?  

T: Yesterday there was a colloquium at our university with someone that spoke about how could we use climate in exoplanets to create a sustainable culture on Earth. Exoplanets are any planets that are not located in our solar system. He explained how by knowing the conditions on these exotic planets we could predict and create more sustainable future on Earth. In the end, he spoke about civilizations, and he mentioned the Dyson sphere as something that surrounds a star and harvests all the energy. On the level of technological development, this would be a type two civilization. That is quite sci-fi.  

M: It is fascinating to think about the idea of a star as a factory.  

T: I believe that we humans should not use the earth and the cosmos as means to fulfill our own ambitions. We should just remember that we are part of the universe. If you are part of something, you do not want to exploit it but rather live with it in collaboration. That said, I am against the idea of a Dyson sphere. I am more in favor of a way living sustainable life without creating too many problems for the planets, which we had already done on the Earth. We could have a very advanced civilization by not burning fossil fuels and other stuff that hurts the environment.  

M: How in that case would we satisfy the ever-growing demand for very high energy experiments?  

T: The official argument against the solar energy is that it is costly and we do not get much out of it yet. In the end, we end up paying more than we get so we use fossil fuels which are cheaper. Unfortunately, they are not sustainable, because they are finite, and after we run out of them, our whole civilization is screwed, together with our environment.

M: What do you think will be the direction to go with energy production?  

T: Solar energy at the moment is a very nice alternative, but I am really hoping for the day when the nuclear fusion will be a thing. That should happen in very close, foreseeable future. I wish I see some nuclear fusion before I die. hahaha

M: Do you think that the next energy source will arrive from the fusion area or some sort of quantum level physical reaction?  

T: Atom level reactions do not create much energy, but nuclear fusion is a real thing, the cleanest type of energy you can get. It is what fuels stars.  

TRIUMF construction


Construction of the cyclotron, January 1972

M: Fundamental research answers key questions that elevate the spirit. Can you elaborate on that?

T: Fundamental research and philosophy are very close. In the past twenty or thirty years, the whole philosophy of science grew apart from science. Additionally, scientists do not really think about what are the philosophical implications of science. Two thousand years ago, when almost all we have now started, science and philosophy were not set apart. “Scientist” of that time began as philosophers. Later, in the 16th century with Galileo and others came the idea of an experiment. At some point, we lost the connection between philosophy and science. There was a lovely hike in the nineteen thirties when we had both quantum mechanics theory and the Einstein’s special relativity. We could pick up from there and continue, but there was the Second World War than we had the Cold War, so the conditions were not right for philosophical discussions. Neither they are now, but that’s a different topic. (Hahaha)

Anyways in what we do, we should not forget that science is very closely related to philosophy and our whole understanding of the universe. We are not engineers. We are just trying to understand what’s going on in the universe. I rather get answers to these fundamental questions than getting a financial reward for doing commercial science.  

M: The connection between science and philosophy for you is in getting answers to the “bigger questions” of the existence of the universe.

T: All of this is connected. When you start asking when and how did the universe began, whether there are any other universes, or if we are the only intelligence in the universe, it is more philosophical. But these are actually also scientific questions that are being researched right now. I think we should reconnect those two because they are attempting to answer virtually the same thing.  

M: where do you exactly see the connecting points between the two?

T: We should remember that all the scientific inquiry we had in the past five hundred years is based solely on Descartes and Newton. They set the foundation of the modern science, but their ideas are outdated right now. We can use the Newtonian physics to describe interactions that we perceive in our ordinary “human” scale.  When you look at tiny objects like atoms or if you get into very high speeds, like those in space, this type of physics doesn’t work. That is why we discovered quantum physics and special theory of relativity. These two theories contain particular philosophical background which had not been yet implemented in much of the science of the twentieth and the twenty-first century. We are mostly still based on that outdated "Newtonianism." That is why all the sciences that still use Newtonian physics to get their own philosophical inputs are founded in the sixteenth-century science and philosophy same as the Newtonian physics itself. And this is also true for the social and economic sciences. We know that this theory was scientifically proven wrong in some cases. Not in all cases. However, we have not yet implemented the quantum mechanics and special relativity in science that much, nor in our everyday lives.  

M: do you think special relativity and quantum mechanics will be one time connected or even unified?

T: It seems like quantum mechanics turns into classical physics when we have objects that are much larger than atoms. There is a threshold at that scale. Unification of these different aspects of physics is very difficult right now.  

M: How important it is to have these different aspects unified?  

T: It will be nice to have them unified. It is ok to have three distinct theories describing the physical world, but we all know that there is actually something larger than that concerning a theory that can describe everything. Scientists are still looking for that.

M: How would we connect to the universe? Should we use philosophy?  

T: Not even that. We should just quiet our minds, and everything will make sense. We live in a world where we are buzzed continuously with everything around us, daily tasks, money, and we don’t just sit down, relax and think about ourselves, what we are doing, why we are here, and so on. The whole socioeconomic system we have is wrong. It’s one hundred percent bad for humans and nature. I think people just need to be connected to nature and the universe. After we relax our minds, everything else will make sense, and we will see the connection with the world.

M: I found one fascinating thing on your website. Were you working on a particle collider in Greece called Democritos? In the context of the fundamental questions in physics research, I found fascinating that there is actually a scientific machine named after Greek philosopher.

T: It’s the atomic theory of Democritus of Leucippus c.460-c.370 BC. Democritus is actually a massive research facility in Athens. They don’t only do nuclear physics but also biophysics and other stuff.

M: It is very poetic.  

T: It’s fun to be greek and do nuclear physics. (hahaha)

M: Is there any more scientific facilities named after philosophers or instruments?  

T: I am not sure, but I will look into that. Most names are acronyms. For example, right now I am working at TRIUMF which stands for Tri-University Meson Facility. Yea, this is a very intriguing question. I have to look into that! There might be some acronyms that correspond to names. Actually, In general, scientists are excellent in creating acronyms with meaning. (hahaha)



c. 460 – c. 370 BC, ancient Greek philosopher of the pre-Socratic era. Together with his mentor Leucippus the atomic theory of the universe.

image: Wikipedia, public domain

Matej VakulaComment