Gemma de les Coves: "We are at the beginning of infinity, but it gives me hope and excitement"

On WhatsApp she has a frame from 8 1/2, by Fellini, because it is a film full of self-references: Mastroianni is at the same time a character and the director of the film; he holds auditions for actresses who then appear in it. Gemma de les Coves (Barcelona, 1984), theoretical physicist and ICREA research professor at UPF, studies the limits of what we can describe, calculate and understand, and she likes how art dives headfirst into these paradoxes, without the fear of conventional logic.

I read about quantum physics and my brain is smoking.

— Honestly, I don't understand what quantum physics tells us about the world either! But we must be humble and not trust our intuition, which was developed to survive on the savanna and not to know how electrons or black holes behave. The fact that humans cannot imagine a quantum superposition is not an argument to deny its existence.

Agreed, words cannot capture it. But what do the experiments demonstrate?

— Quantum mechanics demonstrates that the world is neither local nor realistic.

Is the world not local?

— Local means that there is nothing that can influence another thing faster than light. Quantum mechanics does not allow sending messages faster than the speed of light, but it forces us to abandon the image of a world made of independent pieces.

Is the world not realistic?

— We cannot assume that the properties of things are determined before measuring them, that they exist in a fixed way independently of whether someone wants to know them or not.

And is all this so incomprehensible strongly proven?

— Exactly: assuming that the world is this strange, we can make precise calculations where classical physics fails miserably. And, thanks to these calculations, we make everyday devices like mobile transistors or lasers work.

Why should normal people know about quantum physics?

— I appeal to a sense of wonder about the world. What happens if we keep cutting a piece of paper until we reach tiny scales? The reality becomes phantasmagorical, with properties radically different from the normal ones. It turns out that the world is much richer, stranger, and more beautiful than we imagined.

What do physicists make of this strangeness?

— There are two radically incompatible ways of interpreting quantum mechanics. One says that the superpositions of states are real and that, in every possible outcome, the universe branches into different universes: we live in a multiverse made up of branches to which we have no access. The other says that there is only one universe, but that things do not have objective properties on their own and that everything is relational: their state depends on the relationship with what observes them or interacts with them.

Do you commit to either of the two?

— None of them convince me. Both are incredible, and I would even say outrageous!

There are charlatans who use this strangeness to sell smoke…

— They are those of "quantum medicine" or "quantum consciousness," who want to stretch the idea that "our consciousness modifies reality." They exploit a metaphor that functions as an analogy to explain the result of certain quantum experiments, but which has no connection whatsoever with how reality works.

Your great theme is the paradoxes of self-reference and negation.

— If I say "I am a liar", the sentence contradicts itself: if it is true, I am not being a liar; and, if it is a lie, I am not telling the truth. Its truth value cannot be stabilized. Many problems that have been proven undecidable arise from this paradox, which has devastating consequences for logic.

And does a logic paradox have real-world implications?

— Traveling to the past and killing myself is a paradox of self-reference and negation: if I were to eliminate myself, I would not be able to travel back to eliminate myself. But which comes first, the law of non-contradiction or the law of causality? Perhaps causality emerges from a physical structure that does not tolerate contradictions, perhaps coherence would not just be a rule for thinking correctly, but a restriction on what can exist. I investigate this link between how we know things and how they are.

Draw philosophical conclusions from it.

— Many philosophers have wanted to think of an ultimate limit from the set of all things that are, like Parmenides, and in the set of all that can be said, like Wittgenstein. But by imagining these sets, we implicitly imagine what is outside. And this is a contradiction, because we started from the fact that one cannot speak of anything that remains beyond the totality we have defined. My conviction is that no totality is ultimate, that reality is a plurality of singulars.

How does this make you feel?

— That we are at the beginning of infinity. This can generate unease, but for me it gives hope and inspiration. Unlike a computer program that executes instructions, humans do not get stuck when faced with contradiction and we continue forward. To each landscape we can apply self-reference and negation, transcend it and place ourselves in a new and different scenario, without ever reaching a final closure. As Douglas Hofstadter says, "I am a strange loop".

Is this how you emerged from the existential crisis that led you toward the humanities and to write your book (unpublished and looking for a publisher)?

— I studied physics to understand the world and I became obsessed with universal knowledge, to the point of stopping reading novels: they seemed like stories that were too provincial. Physics offers a view from nowhere and no-time. Chemically, I have no secret ingredient that differentiates me from my environment, but I live trapped in a now and a here, and the matter of my hand is special to me. I realized that the scientific gaze underestimated this reality and I became interested in singulars again.

And now how do you see it?

— We who do science are people and we need the humanities to guide us with values. And vice versa: people in the humanities must understand that science is not a cold and arrogant thing, but an exciting adventure that informs us about the nature of life and death, of time, of the immense rocks that float in space. And of this apparently solid table that, in reality, is almost entirely empty.