Richard P. Feynman (1918-1988).  (DP) physical
Richard P. Feynman (1918-1988). (DP)

The scientist has vast experience of ignorance, of doubt, of uncertainty, and such experience is of the greatest importance. We discovered that in order to progress, it is essential to know how to recognize our ignorance and leave room for doubt. physicist

(Richard P. Feynman, ‘The value of science’)

The title of this article could be that of a long conversation I had with the astrophysicist Juan Perez Mercader in the late eighties. I was trying to get him to write a book for a popular science collection he was directing at the time, and he, while he liked the idea, didn’t see it with complete clarity. they had just left brief history of timein Stephen HawkingIt is The Emperor’s New Mindin Roger Penrose, two books as interesting as they are beyond the reach of the non-specialized public, and I thought that Mercader, a skilful and amusing communicator, could have dealt with the same themes in a more accessible way; but he doubted that certain fundamental aspects of modern physics could be divulged1. Despite this, he ended up sketching out a book project that we worked on for a while, albeit very slowly; so slowly that he would eventually think Juan’s skepticism was justified and it would take him ten years to finish his booktwo.

einstein’s grandmother

They are assigned to einstein two analogous sentences that refer to one of the basic questions of the theory of knowledge. The phrases are: “If I can’t explain it to my grandmother, I don’t understand” and “If I can’t draw it, I don’t understand”. And the question to which they refer is: what does it mean to understand? According to the first sentence, understanding something would imply being able to express it colloquially. It is not enough to know the formula E = mctwo and know that E is energy, m mass and c the speed of light; You have to understand (and it’s not easy), to explain to Einstein’s grandmother, that matter can be converted into energy, since matter and energy are two states of the same thing. According to the second sentence, understanding would be linked to imagination in the most literal sense of the term: the ability to produce meaningful images that allow visualizing the content of a verbal or alphanumeric statement.

At least in theory, any scientific concept could be explained to Einstein’s hypothetical grandmother in simple words, although the explainer had to know very well what was explained and had the necessary time to be able to translate it into colloquial language, through long circumlocutions, that specialized jargon is expressed in a synthetic and precise way. However, not everything is drawable, not even vaguely approximate. We cannot draw something that is both a particle and a wave, and the well-known representation of the atom as a miniature solar system confuses more than it clarifies. That’s why Einstein, a disciple of spinoza it’s from Schopenhauercould never accept quantum mechanics, despite being one of its founders.

One of the great paradoxes of science is that the most effective and accurate physical theory ever formulated, the one that best adheres to observed facts and produces the most accurate predictions, is totally counterintuitive, inherently incomprehensible.3. We can imagine Einstein trying to explain Schrödinger’s cat paradox to his grandmother, and her exclaiming, “Don’t talk nonsense, Albert, how can a cat be alive and dead at the same time?” It may have been such an objection that led him to search in vain for thirty years for “hidden variables” that would allow him to draw physics and reconcile with his grandmother.

nescire aude

In biology, a fundamental textbook can be either a popular work or a textbook. bestseller; is the case of chance and necessityin Jacques Monodany the selfish genein Richard Dawkins. But in physics such a hybridization does not seem possible. The aforementioned books by Hawking and Penrose (some other equally famous and important ones could be added, such as The quark and the jaguarin Murray Gell-Mann) they are bestsellerbut, paradoxically, they are not popular books: a reader without a solid knowledge of physics and mathematics will understand only the introductory chapters and, after confidently advancing through the first few pages, will desperately sink into a sea of ​​unintelligible formulas and concepts, as on those shores where you walk a few meters and suddenly there is a sudden drop in level that prevents those who don’t know how to swim from continuing.

Does this mean we should give up spreading modern physics? Quite the contrary, because disclosing is, to a large extent, making clear the limits of knowledge, the frontiers of science, the hesitations and frustrations of those who venture into the unknown. This is especially important in the case of physics and requires not only great narrative expertise, but also great doses of humility. to the Horatian sapere aude we must add a contrast and complement nescire aude: Dare not to know and admit you don’t know. The first thing a book popularizing modern physics should make clear is that physicists themselves do not fully understand it.

Six Not So Easy Parts

“If I had to pick a single book to pass on to the next generation of scientists, it would have to be six easy pieces», says the prestigious science writer John Gribbin. And definitely the book Richard Feynmann it is the best introduction to modern physics that can be achieved with almost no use of jargon or higher mathematics; but even so, the title is deceptively encouraging: the pieces are only comparatively easy, and Feinman himself warns in the first chapter:

You might wonder why we can’t teach physics simply by stating the basic laws on page one and then showing how they apply in all possible circumstances, just as we do with Euclidean geometry, where we state the axioms and then do all kinds of deductions. . We cannot do this for two reasons. The first is that we still don’t know all the basic laws: the border between knowledge and ignorance is constantly expanding. And the second is that the correct statement of the laws of physics involves some unknown ideas that require advanced mathematics to describe. Therefore, a considerable amount of preparatory training is required even to understand what the words mean.

The mind-matter problem

Going straight to the relationship between mind and matter may seem like a sudden leap, but it is not so much: this old philosophical problem, which in its current scientific approach is often referred to, more specifically, as the mind-brain problem , is one of the questions that , in recent decades, have most intrigued some of the leading physicists, mathematicians and computer scientists, such as Alan Turing, marvin minsky, Hans Moravec, Douglas Hofstadter or the aforementioned Roger Penrose. And one of the reasons, though not the only one, for so much interest is the relationship between the mind-matter problem and artificial intelligence, perhaps the most important scientific and technological endeavor of all time. And, in turn, the mind-matter problem and the artificial intelligence debate are inseparable from the so-called “hard problem of consciousness” (difficult problem of conscience), relating to the how and why of qualia, the subjective qualities of individual experiences.

Coincidentally (or perhaps not), while preparing this article I came across a recently published book that addresses the topic from the triple perspective of physics, computer science, and neuroscience: I am me: analyzing the mystery of consciousnessin Jaime Escutia (Autograph, 2023). The author is a physicist and an expert on operating systems, which enabled him to write an excellent introduction to three closely interconnected key topics: the digital revolution, the new physics (which is already getting old), and the conundrum of consciousness. A highly recommended book for beginners and laymen alike. And although the latter have to work around the complex formulas that inevitably punctuate some of the passages, they will at least be able to have an idea of ​​the magnitude and wonder of what is probably the greatest challenge that human beings have ever faced. in his desire to understand the world and – in a dizzying self-referential loop – his own ability to understand.


(1) “Modern physics” is understood as that after the revolutionary incorporation, at the beginning of the 20th century, of relativity and quantum mechanics.

(2) After several updates, he published it under the title What do we know about the universe? From before the Big Bang to the origin of life (Editora Debate, 2000).

(3) Planck was once told by a disciple of Planck that he was beginning to understand quantum mechanics, and Planck replied, “If you think you understand, you don’t,” and Bohr used to say something similar.