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: What’s the biggest misconception in astronomy?
Many facts are well-known to professionals, but are unappreciated or even rejected outright by the public. "How stars work" takes the cake.

Ethan Siegel

A colorful nebula with a bright center and symmetrical, wing-like clouds of gas and dust extends outward in space, as seen in a JWST reveal that uncovers stars and galaxies in the universe beyond.
Man in a suit posing with a vintage BBC Big Bang 75 microphone.
To Fred Hoyle, the Big Bang was nothing more than a creationist myth. 75 years later, it's cemented as the beginning of our Universe.
Fractal pattern with a stark contrast of vibrant orange and deep blue hues, designed to make the universe visible.
JWST has puzzled astronomers by revealing large, bright, massive early galaxies. But the littlest ones pack the greatest cosmic punch.
inflation spawn parallel universes
When cosmic inflation came to an end, the hot Big Bang ensued as a result. If our cosmic vacuum state decays, could it all happen again?
An image of a starry sky with numerous lines, depicting the concept of space pollution.
In 1957, humanity launched our first satellite; today's number is nearly 10,000, with 500,000+ more planned. Space is no longer pristine.
A diagram illustrating the earth's orbit around the sun with positions indicating seasonal change, including facts about leap day.
Leap day only comes once every four years, including in 2024. But the reason we have it, including when we do and don't, may surprise you.
Lecturer standing in front of a classroom, teaching college admissions students seated at desks with sunlight casting shadows.
There are many problems with relying on SAT and ACT scores for college admissions. But removing them entirely creates less opportunity.
Illustration of the solar system's planets and their predicted fates, with some being swallowed by the sun as it dies and others stripped of their atmospheres or ejected.
For now, our Solar System's eight planets are all safe, and relatively stable. Billions of years from now, everything will be different.
Planets in varying sizes orbiting around a bright central star in a purple-hued cosmos, where life persists.
There are plenty of life-friendly stellar systems in the Universe today. But at some point in the far future, life's final extinction will occur.
A blue t-shirt with a yellow circle and arrow, representing the universe.
The second law of thermodynamics tells us that entropy always increases. But that doesn't mean it was zero at the start of the Big Bang.
An image of a yellow and purple wave with an unclear origin.
Everything acts like a wave while it propagates, but behaves like a particle whenever it interacts. The origins of this duality go way back.
nasa merge black hole
So far, gravitational waves have revealed stellar mass black holes and neutron stars, plus a cosmic background. So much more is coming.
An image of a spiral galaxy taken by the JWST in space.
Almost every large structure in the Universe displays a 5:1 dark matter-to-normal matter ratio. Here's how some galaxies defy that rule.
A choropleth map of the united states displaying median age by county with a color gradient from light to dark blue indicating increasing age ranges following a natural bell curve distribution.
Almost everything we can observe and measure follows what's known as a normal distribution, or a Bell curve. There's a profound reason why.
Comparison of early Mars with abundant water and a thicker atmosphere versus the dry and arid Mars of today, much like Venus, which also died in terms of its potential to support life.
In the early stages of our Solar System, there were three life-friendly planets: Venus, Earth, and Mars. Only Earth thrived. Here's why.
gaia ESA milky way
For thousands of years, humanity had no idea how far away the stars were. In the 1600s, Newton, Huygens, and Hooke all claimed to get there.
Einstein field equations
Although many of Einstein's papers revolutionized physics, there's one Einsteinian advance, generally, that towers over all the rest.
A cluster of galaxies with a star in the middle.
Beyond the planets, stars, and Milky Way lie ultra-distant objects: galaxies and quasars. Here's how far back we've seen throughout history.
An abstract composite image depicting where life began with mountainous terrain, chemical structures, and a monochrome inset of a cloudy sky.
Although early Earth was a molten hellscape, once it cooled, life arose almost immediately. That original chain of life remains unbroken.
A digitally enhanced view of a crescent planet Earth with a galaxy in the background.
The Earth that exists today wasn't formed simultaneously with the Sun and the other planets. In some ways, we're quite a latecomer.
A diagram showing the structure of a galaxy.
The Universe didn't begin with a bang, but with an inflationary "whoosh" that came before. Here are the biggest questions that still remain.