“Contains complex formulas!” It doesn’t seem like the best selling point for a book that aspires to conquer the masses. But theoretical physicist Sean M. Carrollwho also dominates the art of best-seller scientist, achieved it in the United States with The Fundamental Ideas of the Universe: Space, Time, and Motion (Harp, translated by Jordi Giménez Samanes). In it, he reviews the history of fundamental physics in nine concepts (conservation, change, dynamics, space, time, space-time, geometry, gravity, black holes), encouraged by the success of the talks he posted on YouTube during the pandemic. It is the first of a trilogy of books that, he promises, will “become more complex” until reaching the abstract debates on the present and the future of the discipline that animate the episodes of his popular podcast, mindscape.
“Equations are like poems,” he says in an interview in May in his office at Johns Hopkins University in Baltimore. Across the tree-lined street from campus is the institute from which the telescope is controlled. James Webb. Carroll (Philadelphia, 56 years old), comfortable at the intersection between science and culture, has premiered his Natural Philosophy subject here this year, designed for him. “Like a good poem, an equation forces you to think, to interpret,” he adds. “It is short, intense, nothing is left over. And it is impossible to paraphrase it, in the same way that it is impossible to recount the argument of the wasteland [de T. S. Eliot]. The popularization of physics uses analogies, metaphors and anecdotes. I wanted to go further, show readers what is behind the curtain. Although it is not a textbook; It is not necessary to know how to solve them, it is enough to understand them”.
Ask. What is Natural Philosophy?
Answer. It is a knowledge that reminds us that philosophy and science used to be the same. What we now call science was a subset of philosophy. Around 1800, they separated… Today, knowledge is much broader than in Aristotle’s time, and it is impossible to be an expert in everything…
Q. A leading theoretical physicist who also theorizes, like Aristotle, about dramatic art… Is it no longer possible to be a polymath?
R. There is extraordinary access to knowledge in many different areas, but I find it very difficult to be a leading researcher in more than one. Edward Witten comes to mind, one of today’s leading theoretical physicists, who is also the best in mathematical physics. But he doesn’t excel in remote disciplines, like biology or history. Now everything is more compartmentalized, partly because of how universities are organized. I advocate more pollution. There are practical knowledge, like those that are dedicated there in front, in which you do not need philosophy. For example, if you want to locate the farthest galaxy. If you are interested in why big Bang, it will be useful to you. There is a joke that when philosophy begins to answer some questions, it becomes something else: psychology, physics, biology… Newton, who today we consider essentially a mathematician, or a physicist, would have called himself a philosopher. . Nowadays no one would call me that, even though some of my questions are quite philosophical in nature… What is quantum mechanics? Where does the universe come from?…
Q. …Or: Why does something exist instead of nothing?
R. The short answer to that question is that I think it’s an unanswered question. And surely it belongs more to the field of philosophy than to physics. When you ask why there is something rather than nothing, you are assuming that there is a reason, a fundamental fact, why the universe exists. Well, I believe that there is no such fundamental fact. I believe that the universe simply exists.
Q. In the book, he explains that in an expanding universe, energy is not conserved.
R. It depends on what you mean by energy. It is very common in physics that there are ideas that make perfect sense if you live in the time of Isaac Newton. But then came general relativity and quantum mechanics, from which the concept of energy changes its meaning. If you take the energy of this table, of this chair, of the building and of each planet and add up all the photons in the universe and take time into account, then the answer is that energy is not conserved. Because space-time is changing. It’s like if you put a cup of coffee on top of this table, its energy is conserved, but if you throw it into the ocean, it’s not. It is as if the waves were the space-time that pushes the cup.
Q. Do you share the idea that philosophy is somewhat stagnant?
R. No. It seems to me that scientists are unfair to philosophy by asking for tangible results. We are so obsessed with getting the right answers that it’s worth it when we get them even for the wrong reasons. Philosophers are very patient and insightful. They need to make sure that all their words mean something. And they definitely help us illuminate the foundations on which science is built.
Q. The book begins with the formulation of a wish: to live in a world where after work people discuss dark matter in the pub. What would have to change in order for that to happen?
R. A lot. I hope it helps what I say in these books: give people more details. Physics is normally disclosed by resorting to a mystification. Or study reduced to a set of facts to memorize. But the process of science is completely different: it is about formulating hypotheses, often wrong, and collecting data, which is very rarely definitive… Science is the simultaneous sum of the willingness to change your beliefs based on new evidence and the certainty that some of those beliefs are very difficult to change. People are usually willing to believe one of two ideas. Almost never both.
Q. His book can also be read as a treatise on the history of physics, with its turning points and valleys. Where is discipline now?
R. When it comes to fundamental physics we are not at a tipping point. Some people complain that we don’t have revolutionary ideas like those of a century ago, and it seems unfair to me: that was a very, very special time. We discovered relativity and quantum mechanics, particle physics and the model of big Bang. You can’t expect that to happen every 50 years. But at the same time there are parts of high-level physics, complex systems, thermodynamics, statistical mechanics, fluctuations, biophysics… there are still fruits within reach, because we are at a very basic level. . That’s what my third book will be about.
Q. How is it possible that, a century later, we are still unable to explain more than 5% of the universe?
R. It is true that the particles that we have detected in experiments constitute only 5%. 25% is dark matter. 70% is dark energy. We haven’t detected them in the laboratory, but we know they are there, and we know some of their properties. We actually know quite a bit about them, although we’re not quite done figuring out what they are. It seems to me that understanding 5% of the universe is a lot.
Q. Everyone remembers what he was doing on 9/11 or when Michael Jackson died. In your profession, the question must be: What were you doing when the Higgs boson was discovered?
R. [Risas]. He was at the CERN press conference and I even wrote a book. It was very exciting. But to be fair, and without wanting to detract from it, we expected to find something else, a lot of other things. We awaited a revolution, the dawn of a new golden age. It didn’t happen.
Q. Did you like the Oscar All at once everywhere?
R. I loved. The idea of the multiverse arises in physics from string theory and the 10 dimensions it proposes and how they can interact with each other. They would be different universes, with different physical laws.
Q. The big question from humanism is: where does that theory leave identity? The protagonist of the film not only discovers that the multiverse exists; also that she lives in the worst version of her…
R. The moral of the movie is that it’s not quite like that either, after all. But yes, the thought of having twins out there making slightly different decisions than you does raises some deep questions. It is convenient to differentiate between multiverses. There is the cosmological, which implies that there are regions of the universe very far away in space-time in which the conditions are very very different, and the laws of physics, too. That concept is derived from string theory, the world is not made of particles, but of loops of strings, or what we call cosmological inflation. [la demasiado rápida y temprana expansión del universo]. Both belong to speculative physics and are far from proven, but they are very popular. Then there are the many worlds of quantum mechanics. This is actually much more likely to be true. It’s a pretty deep issue, and we’re still struggling with how to deal with it as physicists and as philosophers.
Q. Was the recent announcement that the United States is close to nuclear fusion bloated?
R. I’m always frustrated by those press releases, because there’s clearly a vested interest in communicating a big discovery. In reality, they have not achieved a reaction that generates more energy than it took to make the reaction. What they do is quick bookkeeping, so they don’t include some of the energy they invest. The merger could be a breakthrough. But it does not seem to me that it will be a matter of a couple of years, but rather of decades.
Q. Are you concerned about the advancement of artificial intelligence?
R. I am not alarmist about it. I don’t think there is a reasonable chance that it will kill millions of people or make the human race extinct. What is much more likely is that it paves the way for human rights violations, attacks on privacy and misinformation in political campaigns.
Q. Do you allow your students to use ChatGPT?
R. I haven’t had a chance yet. He software it launched right after my classes ended last semester. It seems to me that there is no other. It is as if a math teacher does not allow his students to use a calculator at home to multiply five-digit numbers. I have used ChatGPT: I know she doesn’t write very good essays, she lies all the time, invents things and misinterprets others, but she knows a lot and can be very useful and even inspiring. The trick is to take it as a tool.
Q. Let’s finish with another of his obsessions: free will…
R. I am in favor of free will. As with energy, it depends on what you mean by free will. The most positive way to think of other human beings is as agents who make decisions for given reasons. Sometimes they will do it for irrational reasons. That is so, even if we admit that the underlying laws of physics are perfectly deterministic, which they are not, due to quantum mechanics. But even if they were, it’s too complicated to predict exactly what a human being is going to do. For me that is free will.
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