The Cosmos


Do We Live in a Multiverse?

Sometimes the world seems suspiciously perfect. There seems to be no rhyme or reason for why gravity is 1036 times weaker than electromagnetism. Or why a neutron is 1.00137841870 times heavier than a proton. But these seemingly random, yet precise, values landed in the extremely narrow window that would allow life to exist.

How did we end up in such a precariously balanced universe? How did we get so lucky?

Some physicists think there could be many—maybe infinite—universes. Other universes could be empty—or they could be full of things we never imagined. Perhaps we just live in the only one that can support us.


Go Deeper
Picks for further reading

Harper’s Magazine: The Accidental Universe: Science’s Crisis of Faith
Alan Lightman delves into the history of the fine-tuning problem—and makes a case for the multiverse.

The Nature of Reality: Is the Universe Fine-Tuned for Life?
Anil Ananthaswamy examines the scientific community’s support for and resistance against the possibility of a multiverse.

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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?!”