Interview with Michal Malinský, an Expert in Grand Unified Theories

I feel confident to say that this is the best interview here so far. Michal Malinský works at the Charles University in Prague and is an expert in a special type of models beyond the standard model, called Grand Unified Theories. He shares many invaluable tips and book recommendations for students who want to work on models beyond the standard model. In addition, we talk about his favorite books, his biggest discovery and much, much more.

Without further ado, meet Michal Malinský.

Physics Insider: What are you currently working on?

Malinský: As with almost everyone in the theoretical high-energy physics there are several things I’m currently interested in/working on in parallel. Besides the regular teaching duties (about three hours a week) and the daily reading through the new preprints in the “standard” repositories (namely hep-ph, hep-th and hep-ex sections of the “canonical” arXiv.org) which, together, take about 1/3 of my time, I’m mostly involved in the subject of the perturbative baryon and lepton number violation in physics beyond the Standard Model (BSM) and adjacent fields (neutrino physics, BSM flavour, supersymmetry etc.) In particular, I’m focusing on the long-standing issue of the possible quantum instability of the proton and the idea of grand unification of the SM gauge interactions which represents one of the most promising, yet very conservative approaches to this conundrum. Unfortunately, it is almost impossible to squeeze any robust estimate of its lifetime out of the existing theories because of their generic sensitivity to various uncertainties in both the input data as well as in the methods used in calculations; currently, my small research group here in Prague is working on a systematic account of these effects in several promising unified scenarios. Besides that, I’m interested in conceptual issues of gauge field theories such as their vacuum and gauge hierarchy stability. Recently, I begun drifting a bit towards particle cosmology which is a thriving subject with a wide interface with what I was mainly interested in so far.

Physics Insider: Why is this important?

Malinský: Well, besides addressing the fundamental philosophical question about the ultimate rules governing the entire Universe there are many aspects that make this kind of research important, at least in my eyes. Concerning, for instance, the proton decay issue, it has to do with the stability of the very substance that everything we can see around (including ourselves) is made of. To this end, there are continuous experimental efforts to observe any signal of the assumed spontaneous proton disintegration process; to date, however, we did not see any convincing evidence for that. Yet, from the theory perspective, we are pretty certain it must occur at some level and there are simple arguments that we may be indeed very close to observing it. However, the higher the existing proton lifetime limits are (currently, at the level of some 10^34 years) the bigger machines (nowadays at the level of tens of kilotons of the ‘active’ material, typically water) are needed to proceed deeper to the “Terra incognita” hoping the upcoming experiments will finally see something. This, obviously, is a very costly enterprise and, in practice, it is always difficult to secure the funding for the next-generation (currently, megaton-scale) facilities; in that respect, any robust prediction of the proton lifetime would strongly support these efforts. In a wider perspective, observing proton decay would be, in its impact, comparable to the recent discovery of the “holy grail of particle physics”, the long-sought Higgs boson.

Physics Insider: What was the biggest advance/discovery in your field in the last 20 years?

Malinský: There have been several indeed. Besides the big Higgs story and the continuously piling indirect evidence for the enigmatic dark matter permeating the entire Universe perhaps the most influential was the experimental observation of what is nowadays called the “neutrino oscillations”. This is a subtle quantum effect which, roughly speaking, makes the neutrino, the most feeble of all the known fermions, a ‘phantom’ particle that, under certain conditions, behaves in a very different way than how it should according to the Standard Model. In fact, neutrino oscillations are often regarded to as the first firm laboratory-level evidence that the old good Standard Model is not a complete theory of the microcosmos and that there is a bigger and better theory behind that will encompass these phenomena. From here, there is only a small step into the realm of physics in which the aforementioned lepton and baryon number conservation laws are not as scared as we thought they are.

Physics Insider: What was your biggest discovery?

Malinský: This is the kind of question that should rather be answered by someone else… 😉

What I personally consider to be my best contributions to the field are two results in the realm of the grand unified theory (GUT), namely, the concluding proof we provided back in 2006 together with my former colleagues Stefano Bertolini and Thomas Schwetz that a certain very popular class of supersymmetric GUTs can not be compatible with all the experimental data, and the observation from 2010 (together with Luca di Luzio and, again, Stefano Bertolini) that one of the simplest and most predictive grand unifications that was for various reasons abandoned back in 1980’s turned out to be not only a perfectly viable framework but, perhaps, even the most precise theory of proton decay ever formulated – what we did was that we took the model at the strictly quantum level and we identified a subtle effect which turned over the almost hopeless situation entirely. Besides this, I’m also proud about a couple of results obtained in collaboration with my friends Werner Porod, Florian Staub and Renato Fonseca in the realm of the renormalization theory which, in a sense, finished a programme that started three decades ago by a series of seminal papers by Marie E. Machacek and Michael T. Vaughn.

Physics Insider: What is your advice to a student who wants to make a career in your field?

Malinský: Do not wait for the lecturers to teach you, get a good book and go ahead on your own. Be honest; if you do not get everything straight on the first reading just read through again. Talk to your tutors, friends and anybody who knows. Get ready to travel and spent as much time abroad as you can. Become an expert in an important subject but strive to maintain the big picture. Explore. Teach. And most of all, take it easy!

Physics Insider: If some fairy would offer to answer you one question about nature; what would it be?

Malinský: Well, as unequipped as I feel as a particle physicist to even phrase such questions it would probably be something like “What is it that makes us conscious?” or, in one of its variants, “Why is it that in spite of the ‘hardware-level’ equivalence of all human beings my mind is ‘attached’ to only one of them?” or that kind. If, however, I was confined to questions about my field then, maybe, I would resort to the Lawrence Krauss’s popular “Why there is something rather than nothing?” or, if you want me to be even more specific, “What’s the big dark thing out there that dominates the matter in the Universe?”

Physics Insider: How far do you think are we away from answering this question?

Malinský: As for the origin of consciousness I must say I have absolutely no idea. I’m not even sure this is a kind of question that mankind should ever receive an answer to – perhaps it’s better to keep it really just for fairies… Concerning the ‘real physics’ queries above I would still be surprised if we ever got a full answer (actually, how would we ever know it was complete?) However, with these we can at least hope for a gradual learning and improvement on both the experimental as well as the theory sides. Indeed, there are massive efforts underway to build bigger and better experiments that should shed at least some light on the nature and perhaps even the origin of the dark matter. Let me cross my fingers and say I believe we’ll get a breakthrough in this business within a decade or two.

Physics Insider: If you could give your 20 year old self one piece of advice, what would it be?

Malinský: The obvious one would be “Work harder, buddy!” but, to me, this common exclamation only makes sense together with the complementary “Think!” which would amount to one too many. Hence, I’d perhaps suggest myself something like never to forget about the bigger perspective because, without it, one is in a permanent danger of loosing the drive and, soon after that, even the motivation to push further.

Physics Insider: What math is necessary to be able to work in your field?

Malinský: Well, the basic math that anybody working on the BSM physics should know (besides the ‘elementary’ calculus, i.e., arithmetics, algebra & analysis) is namely the theory of Lie groups/algebras and their representations which, indeed, is in the very core of the quantum theory and the GUTs in particular; it is also very handy if you know at least something about probability & statistics and about computer sciences. However, if you want to do a cutting-edge research in the (post)modern disciplines such as the string theory, dualities etc. then you should know a lot about geometry, topology, functional analysis and other “arcane” subjects too.

Physics Insider: Which books do you recommend to someone who wants to do research in your field?

Malinský: If you meant ‘to start doing research’ in particle physics then, as a true basis, I’d recommend five textbooks that are all excellent in being written in a very ‘human’ and comprehensible style but ‘sharp’ enough to avoid unnecessary simplification (which, in a highly abstract discipline such as the quantum theory is not always the best strategy).

These are, topic-wise:

As for the really advanced topics at the forefront of the current research there are usually no books available (not at least until the dust settles) and the most recent information is either published in journals and preprint servers or presented at the conferences and workshops.

Physics Insider: Which books did influence you the most?

Malinský: For me, the highest ranking of all physics books I have ever read is Sidney Coleman’s ‘Aspect of symmetry’. In fact, it even happened to be the first quantum field theory book I have ever come across; it was at the 3rd year of my bachelor studies when I was given a copy of it by my supervisor (actually, it was a Russian translation which few years after the change of the regime in my home country was still virtually the only one available at our libraries) and I was learning from it bit by bit the basics about the Goldstone theorem and the Higgs mechanism. As a matter of fact, I really appreciated the depth of the concepts discussed there only when I returned to this book some 10 years later (already with the English original at hand) as a young postdoc. Besides this, I cherish the three QFT volumes by Steven Weinberg which, however, are not an easy reading but, if you do your homework, they are extremely rewarding.

Physics Insider: What was the best physics or math book you’ve ever read?

Malinský: Barring all the textbooks discussed at length above which shaped my path at later stages I’d like to mention one semi-popular book that I found as a 10-year old boy in my father’s bookshelf – the ‘Universe’ by Z. Horsky, J. Grygar and P. Mayer (in Czech) – which, as far as I can recall, kindled the first sparks of my interest in astronomy and physics in general. It was a huge and thick volume that I could hardly even manipulate back then, full of coloured pictures of nebulae, galaxies, planets and other cosmic objects, that fuelled my fantasy for many evenings when I was first trying to read through the text therein. It was the best book in the sense that it motivated me to make the (most difficult) first steps towards physics.

Physics Insider: What do you wish you would’ve known earlier in your career/ when you started studying physics?

Malinský: I recall I was often questioning myself whether I was “good enough” to pursue a career in theoretical physics which, as I thought, was a domain of only especially gifted people among which I never counted myself. Only later on I understood that the talent is just one of many prerequisites of success in this endeavour and that there are many other important qualities that must at least complement (if not overwhelm) it. Thus, in the early days of my studies I would have certainly benefited from realising that most of the greatest achievements in physics are due to “ordinary human beings” and what matters is the will to work and study rather than the actual level of knowledge. Later on, towards the end of my bachelor studies, I would have appreciated a warning from someone that earning living in physics is one of the most difficult ways of doing it which, furthermore, only seldom brings a lasting reward in either a nice formula on the blackboard or a long-sought insight. Nevertheless, for me, even such bits are worth it.

Physics Insider: Mr. Malinský, we thank you for this interview.