Starts With A Bang

A field of stars and colorful cosmic dust clouds scattered across the dark expanse of space.
The Universe is out there, waiting to be discovered

Our mission is to answer the biggest questions of all, scientifically.

What is the Universe made of? How did it become the way it is today? Where did everything come from? What is the ultimate fate of the cosmos?

For most of human history, these questions had no clear answers. Today, they do. Starts With a Bang, written by Dr. Ethan Siegel, explores what we know about the universe and how we came to know it, bringing the latest discoveries in cosmology and astrophysics directly to you.

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Ethan Siegel is an award-winning PhD astrophysicist and the author of four books, including The Grand Cosmic Story, published by National Geographic.

Full Profile
A bald man with a long beard and handlebar mustache gestures with his hands against a backdrop of an upside-down cityscape wearing a purple shirt.
Ask Ethan: Can someone possibly see the edge of spacetime?
Our Big Bang could be just one region within an infinite, inflating multiverse. If we were born close to the cosmic edge, what would we see?

Ethan Siegel

A satellite orbits Earth against a backdrop of space. Below, the Earth's curvature and cloud formations are visible, making our planet seem even bigger.
The observation that everything we know is made out of matter and not antimatter is one of nature's greatest puzzles. Will we ever solve it?
zero gravity flight stephen hawking
The mass that gravitates and the mass that resists motion are, somehow, the same mass. But even Einstein didn't know why this is so.
Interior of a particle physics laboratory showing a complex particle accelerator setup with multiple cables, detectors, and machinery designed to study glueball particles.
Scientific surprises, driven by experiment, are often how science advances. But more often than not, they’re just bad science.
JWST deep field vs hubble
The "little red dots" were touted as being too massive, too early, for cosmology to explain. With new knowledge, everything adds up.
Comparison of weight on Earth and Mars for a 1 kg mass. On Earth: gravity = 9.81 m/s², weight = 9.81 N. On Mars: gravity = 3.72 m/s², weight = 3.72 N; demonstrating that weight and mass are not the same across different planets due to varying gravitational forces.
Here on Earth, we commonly use terms like weight (in pounds) and mass (in kilograms) as though they're interchangeable. They're not.
So far, Earth is the only planet that we're certain possesses active life processes. Here's what we shouldn't assume about life elsewhere.
cosmic inflation
The Universe isn't just expansion, but the expansion itself is accelerating. So why can't we feel it in any measurable way?
A colorful, abstract scientific illustration with a central glowing sphere, circular patterns, and various lines and circles suggesting quantum connections or uncertainty data points, on a dark background with blue accents.
No matter how good our measurement devices get, certain quantum properties always possess an inherent uncertainty. Can we figure out why?
first contact
Life arose on Earth early on, eventually giving rise to us: intelligent and technologically advanced. "First contact" still remains elusive.
A circular illustration depicting the observable universe with various galaxies, stars, and cosmic structures emanating from a central point, symbolizing the solar system and hinting at how far away the Big Bang occurred.
If you think of the Big Bang as an explosion, we can trace it back to a single point-of-origin. But what if it happened everywhere at once?
every square degree
The Universe is 13.8 billion years old, going back to the hot Big Bang. But was that truly the beginning, and is that truly its age?
cosmic inflation
Many contrarians dispute that cosmic inflation occurred. The evidence says otherwise.
pulse light quantum tunnel barrier
In all the Universe, only a few particles are eternally stable. The photon, the quantum of light, has an infinite lifetime. Or does it?
Raisin bread expanding Universe
The big question isn't whether the Universe is expanding at 67 or 73 km/s/Mpc. It's why different methods yield such different answers.
A painting of a group of people standing in front of a church.
The original principle of relativity, proposed by Galileo way back in the early 1600s, remains true in its unchanged form even today.
A vast expanse of outer space densely populated with numerous stars, including the typical star, and celestial objects of varying brightness against a dark background.
Most stars in the Universe are located in big, massive, Milky Way-like galaxies. But most galaxies aren't like ours at all.
A worker in a hard hat and safety vest adjusts equipment in a facility alongside large red machinery labeled "Jefferson Lab." The scene fades into concentric circles, as if drawn by the powerful collider, leading to a bright light.
The largest particle accelerator and collider ever built is the Large Hadron Collider at CERN. Why not go much, much bigger?
Einstein
More than any other equation in physics, E = mc² is recognizable and profound. But what do we actually learn about reality from it?
two particles different wavelength speed of light
The Michelson-Morley experiment of 1887, despite expectations, revealed a null result: no effect. The implications were revolutionary.
For centuries, Newton's inverse square law of gravity worked beautifully, but no one knew why. Here's how Einstein finally explained it.