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Illustrated portrait of Christopher Fuchs. Lauren Tamaki for Vox

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Christopher Fuchs is revolutionizing how we understand our quantum reality

The physicist and co-founder of the QBism theory is shaking up his field.

Bryan Walsh is an editorial director at Vox overseeing the climate, tech, and world teams, and is the editor of Vox’s Future Perfect section. He worked at Time magazine for 15 years as a foreign correspondent in Asia, a climate writer, and an international editor, and he wrote a book on existential risk.

In the intricate and often bewildering world of quantum mechanics, Christopher Fuchs, a physicist at the University of Massachusetts Boston, stands out as a maverick thinker. QBism, the interpretation of quantum mechanics that he and some of his colleagues helped create, marks a bold divergence from traditional explanations of quantum reality, much like a revolutionary turn in a complex strategic game, unveiling new layers and perspectives of understanding how our universe works.

Fuchs’s journey into quantum mechanics echoes the adventurous spirit of a player navigating a realm filled with enigmatic principles. Where classic interpretations of quantum physics, such as the Copenhagen and many-worlds theories, present a reality of randomness or branching universes, QBism introduces a radical subjectivity. The theory holds that the probabilities in quantum mechanics are reflections of personal belief, shaping an observer’s expectations rather than outlining an objective reality.

In this view, reality is not a pre-written script but a participatory drama, with each observer playing a crucial role in shaping their experience. As Fuchs put it in a lecture earlier this year, in QBism, “when I take an action on the world, something genuinely new comes out.”

This philosophical pivot has profound implications. It challenges long-held notions about the observer’s role in the physical universe, bridging the gap between consciousness and the physical world, a mystery that has long perplexed scientists and philosophers. Practically, it paves the way for innovative approaches in quantum computing and information science — two exciting fields that stand to have major impacts on the path of technological growth in the 21st century.

Fuchs’s approach has its critics. Some in the scientific community view QBism as a departure from the objective pursuit of understanding quantum mechanics, as if he had changed the rules in the middle of the game. But it’s precisely this disruption that underscores the significance of his work. QBism invites us to rethink our role in the cosmos, not as passive observers but as active participants. “The QBist vision is that of an unfinished universe, of a world that allows for genuine freedom, a world in which agents matter and participate in the making of reality,” writes Ruediger Schack, one of the co-founders of QBism.

This is difficult stuff, and it takes a mind as searching and as relentless as Fuchs’s to work through it. His collected emails working out the mechanics of QBism stretch to the thousands of pages, revealing an erudition that can feel like a throwback to the days of scientist-philosophers like Robert Oppenheimer. As the physicist David Mermin has said: “If Chris Fuchs did not exist then God would have been remiss in not inventing him.”

QBism reminds us that progress often comes from those who dare to question the status quo and view the universe through a different lens. In the intricate game of understanding our universe, Fuchs’s QBism represents a masterful move, challenging established rules and inviting a new way of engaging with the quantum world. Thinkers like Fuchs inspire us to consider that the next significant leap in our understanding may arise from those who play the game differently, reshaping the very rules we thought we knew.

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