Exploring the Boundaries of Possibility: Chiara Marletto's Counterfactual Science

In the margins of history, from Bach to Beethoven, we have always dared to imagine the unimaginable. Science, with its gift of revealing reality, constantly challenges our assumptions about what is possible. Italian physicist Chiara Marletto, in her book 'The Science of Can and Can't', delves into this dynamic by exploring counterfactuals—explanations of what could or could not happen in the universe. These counterfactuals offer fresh perspectives on mysteries of nature, challenging the stagnation in scientific discovery by encouraging radically different modes of explanation.

Counterfactuals, Marletto argues, are essential for understanding phenomena like information, time, and free will. They allow us to see beyond the limitations of traditional physics, which often focus solely on predictions based on initial conditions and laws of motion. By examining contradictions and revising assumptions, as with the discoveries of Neptune and the neutrino, we can expand our understanding of reality.

Marletto emphasizes resilience, not just in the biological sense, but as a fundamental property of information that sustains physical reality. This resilience is key to the perpetuation of knowledge, which she describes as the most resilient substance in the universe. Drawing on Karl Popper's philosophy, she highlights the importance of fallibilism—the idea that progress is possible through the identification and correction of errors.

Creativity, both in nature and human thought, is a generative process that Marletto contrasts with natural selection. While natural selection requires each step to be viable, human thought can leap, allowing for the creation of new knowledge. However, she warns against the stagnation that can occur when dogmas limit our ability to conjecture and criticize.

Marletto's work is a love letter to science and the art of explanation. She celebrates physics as a source of endless wonder, not just for its calculations, but for the explanations that unify our understanding of the universe. These explanations reveal unseen elements that are crucial for understanding the physical world.

Using the myth of Theseus, Marletto illustrates how counterfactuals are integral to storytelling and sensemaking. The ability of a ship's sails to signal information is analogous to the binary states of information in our digital world. By considering counterfactuals, we bring abstract concepts like information and knowledge into the realm of physics, challenging the notion that they are mere abstractions.

In a vignette set in Ancient Greece, Marletto imagines young Alexander the Great questioning what enables him to wonder and appreciate abstract concepts. Aristotle suggests that the mind, though obeying the same laws as physical objects, possesses unique properties that allow it to engage with the abstract.

Marletto's exploration of counterfactuals opens new portals to possibility, encouraging us to embrace the unknown and continue the quest for understanding in a universe full of potential.