Why Do We Exist?: The Nine Realms of Universe That Make You Possible

A boundary-breaking astrophysicist reimagines the universe--and our place within it--in this audacious journey through the Nine Realms of the cosmos.

"This book explains the universe and then quietly explains you. Which is unfair, because I was just trying to read about space. . . . Smart, funny, and unexpectedly moving."--Sarah Silverman, comedian

The universe gave rise to everything: stars and cells, minds and memories, purpose and pain. But it doesn't care about us. It follows its own rules. And now, according to Dr. Hakeem Oluseyi, we finally understand enough about those rules to ask the big questions like we mean it: Why do we exist? Are we alone? How did we get here? What comes next? And--perhaps most urgently--is there reason to hope?

Heck yeah, there is!

Dr. Oluseyi is no ordinary scientist. A former street kid turned world-renowned cosmologist, he realized something bold: The story of existence can be told as a passage through nine interwoven realms--each revealing a new layer of cosmic truth.

There's the Middle Realm, where we live; the Realm of Life, where organisms flourish across the vastness of space; the Cosmological Realm, where galaxies dance and collide; the Dark Realm, dominated by unseen energy and invisible forces; the Quantum Realm, where reality defies intuition; the Temporal Realm, where time begins, flows, and perhaps ends; the Multiverse Realm, where our universe may be one among many; the Realm Beyond Horizons, where observation breaks down; and the Realm of Imagination, where insight, curiosity, and creativity shape our understanding of it all.

In Why Do We Exist?, Dr. Oluseyi cracks open these realms with clarity, humor, and radical honesty, bridging cutting-edge physics, personal narrative, and philosophy. The result is a blueprint for understanding reality itself and a surprising case for human potential in an indifferent cosmos.

This isn't just a science book. It's a survival manual for the universally curious.

Author: Hakeem Oluseyi
Publisher: Ballantine Books
Published: 04/21/2026
Pages: 256
Binding Type: Hardcover
Weight: 0.84lbs
Size: 8.55h x 5.78w x 0.90d
ISBN: 9781984819123


Review Citation(s):
Publishers Weekly 02/23/2026
Kirkus Reviews 03/01/2026

About the Author
Dr. Hakeem Oluseyi, author of the critically acclaimed memoir A Quantum Life: My Unlikely Journey from the Streets to the Stars, is a multidisciplinary astrophysicist, multi-patented inventor, award-winning author and journalist, internationally recognized educator, and highly sought-after TV presenter, podcast host, voice actor, and keynote speaker.