Gravity / Quantum Physics


The Biggest Puzzle in Physics: Reconciling Quantum Mechanics and General Relativity

Sometimes the biggest puzzle in physics seems like the worst relationship in the universe. Quantum mechanics and general relativity are the two best theories in physics, but they have never been able to get along.

Quantum mechanics successfully describes the world of the very small, where nothing is predictable and objects don’t have precise positions until they are observed.

General relativity does well with describing massive objects. It says that the world behaves in a precise, predictable way, whether or not it’s observed.

Neither one has ever failed an experimental test. But so far no experiment has been able to show which — if either — of the two theories will hold up in the places where the two converge, such as the beginning of the universe and the center of a black hole.

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Greg Kestin

    Greg Kestin holds a faculty position at Harvard University, where he conducts theoretical physics research, teaches, and produces educational online content. He earned his physics Ph.D. from Harvard, as a member of The Center for the Fundamental Laws of Nature, focusing on theoretical particle physics and quantum field theory. Over his career, he has also conducted research in nuclear physics, fusion energy, and gravitational wave physics. For over a decade he has been involved with innovative educational outreach endeavors, bringing science to both students and members of the public through his writings, videos, lectures, and multimedia.

    Samia Bouzid

    Samia Bouzid is a multimedia storyteller with a passion for science, especially physics. She is a production assistant for NOVA’s YouTube series “What the Physics?!”