—"Quantum physicist Hugh Everett III proposed a theory that every decision and choice we make creates an infinite number of parallel universes."

In the midst of confusion, Ryu Seoha recalled the words of Dr. Han Kangseok that she had heard once before.

—"Everything, people, objects, the world itself, is ultimately made of particles. Particles in the microscopic world can exist in all possible locations at once."

At the time, terms like quantum mechanics, wave function collapse, Schrödinger’s equation, multiverse theory, and the many-worlds interpretation had seemed difficult and of little interest to her. She had only listened, thinking that someday, …