Quantum Physics and the Consciousness of the Universe. Second expanded edition.: The double slit, superposition, entanglement. The need for conscious observers for the existence of the world.

The question that has been inflaming physicists and philosophers for decades is surprising: would the universe exist if there were no conscious observers? Already in 1931, Max Planck stated: "I consider consciousness to be fundamental. Everything we talk about, everything we consider, exists only thanks to consciousness."

This view found fertile ground in the quantum phenomena of the 20th century. The double-slit experiment, first conducted by Thomas Young in 1801 and reinterpreted in quantum terms, shows how a particle changes its behavior when observed. According to some physicists, without a conscious observer, reality remains in an undefined and probabilistic state.

Another key concept is quantum entanglement. When two particles are entangled, any change in one of them instantly causes a corresponding change in the other, regardless of distance. Since the 1980s, experiments such as those conducted by Alain Aspect at the University of Paris have confirmed that entanglement is real. The message seems clear: at the heart of reality, everything is connected. Even consciousness seems to be part of this universal network.

David Bohm, a physicist and student of Einstein, proposed in the 1980s that the universe is a super-hologram, an interconnected structure in which each part contains information about the whole. Bohm argued that human consciousness is linked to this universal structure. "Deep within the universe," Bohm wrote, "there is an implicit order, a fundamental unity that embraces matter, mind, and consciousness."

This perspective echoes ancient Eastern philosophies. In Buddhism and Hinduism, the idea that the individual self is part of a cosmic consciousness has been taught for millennia. In the 1950s in Zurich, philosopher Carl Jung formulated the concept of the collective unconscious: a dimension in which thoughts, memories, and archetypes circulate in a kind of Platonic "space of ideas" located beyond the individual mind.

Today, to say that consciousness is simply a product of the brain seems reductive. Quantum physics has led contemporary thinkers to reevaluate the metaphysical roots of reality. Since the 1990s, Roger Penrose has proposed that human consciousness is linked to quantum effects in the microtubules of neurons.

Perhaps, as the great physicist John Archibald Wheeler suggested in the 1980s, the universe is participatory. The very act of observing helps shape reality. The question that this second edition starts from is simple and disturbing: are we participants in a universal consciousness?

Whether it be mystical visions in India or experiments in the heart of the West, quantum physics continues to suggest that the world does not really exist without a consciousness capable of observing it. And that perhaps the human mind is only a spark of the great consciousness of the universe.