Dark Matter and Dark Energy

What is the universe made of? Everything we see, from stars to planets and gas, accounts for only 5% of the cosmos. In 1933, Zwicky observed that galaxies in the Coma cluster were moving faster than visible matter could explain. In the 1970s, Vera Rubin found that the edges of galaxies were rotating too quickly. Then, through gravitational lensing and the Bullet Cluster, we discovered unseen matter. In 1998, we faced a second surprise: the universe is expanding at an accelerating rate, driven by a mysterious energy we know little about.

This book is written in accessible language, filled with everyday examples, and requires no prior physics education—only curiosity. Each chapter concludes with a summary box, making complex concepts easier to digest. Written by Dr. Moataz Ibrahim, PhD in physics, it invites readers to explore the unknown realms of dark matter and dark energy.