What Is General Relativity?
A thorough explanation of Einstein's general theory of relativity: from the equivalence principle to curved spacetime, gravitational waves, black holes, and why GPS depends on it.
March 2025
August 2024
What Is Cosmology? The Origin, Structure, and Fate of the Universe
Cosmology is the scientific study of the universe as a whole — its origin in the Big Bang, its large-scale structure, the mysteries of dark matter and dark energy, and its ultimate fate.
July 2024
How the Universe Began: The Big Bang and What Came Before
The Big Bang is the best-supported scientific account of the universe's origin — but it raises as many questions as it answers. What happened in the first seconds, what existed before, and what caused it all.
June 2024
Dark Matter and Dark Energy Explained: The 95% of the Universe We Can't See
Dark matter and dark energy together make up 95% of the universe, yet neither has been directly detected. Learn what they are, why we know they exist, and what scientists are doing to find them.
February 2023
What Is Dark Matter and Dark Energy: What We Know and Don't Know
Dark matter and dark energy make up 95% of the universe, yet neither has been directly detected. Here is what scientists know, suspect, and cannot explain.
June 2022
What Is Astronomy?
A comprehensive guide to astronomy: its history from naked-eye observation to the James Webb Space Telescope, stellar physics, black holes, exoplanets, and the search for extraterrestrial life.