Ethan Siegel

Ethan Siegel

A theoretical astrophysicist and science writer, host of popular podcast “Starts with a Bang!”

Ethan Siegel Starts with a Bang!

Ethan Siegel is a Ph.D. astrophysicist and author of "Starts with a Bang!" He is a science communicator, who professes physics and astronomy at various colleges. He has won numerous awards for science writing since 2008 for his blog, including the award for best science blog by the Institute of Physics. His two books "Treknology: The Science of Star Trek from Tricorders to Warp Drive" and "Beyond the Galaxy: How humanity looked beyond our Milky Way and discovered the entire Universe" are available for purchase at Amazon. Follow him on Twitter @startswithabang.

A view of deep space showing numerous galaxies of various shapes and sizes scattered across a dark background.
To learn how our Universe grew up, we have to look at large numbers of galaxies at all distances to find out. Good thing we have JWST!
A colorful, irregular galaxy with bright clusters of stars, some possibly from a generation stars before sun, and nebulae against a dark background scattered with distant stars.
Our Sun only arose after 9.2 billion years of cosmic history: with many stars living and dying first. How many prior generations were there?
Since the time of Galileo, Saturn's rings have remained an unexplained mystery. A new idea may have finally solved the longstanding puzzle.
Two illustrations: on the left, a ball bounces back after hitting a wall; on the right, inspired by quantum advances, the ball passes through—echoing breakthroughs honored with the Nobel Prize in Physics. A child throws the ball in both scenarios.
Quantum mechanics was first discovered on small, microscopic scales. 2025's Nobel Prize brings the quantum and large-scale worlds together.
From the vastness of space, Earth at night reveals its exo-earth beauty, with illuminated continents showcasing a tapestry of lights across North and South America. Major cities and regions emerge from the glowing darkness, painting a vivid picture against the backdrop of oceans.
In 2025, Earth remains the only planet where life is known to exist. Without a second example, "The Stand" has a vital lesson to teach us.
A split image shows a star field on the left and a COSMOS-Web survey area diagram on the right, with labeled NIRCam and MIRI footprints alongside the moon for scale, highlighting galaxies explored by JWST science.
By deeply imaging a large volume of space, COSMOS-Web provides JWST's widest cosmic views. Its gravitational lenses reveal a big surprise.
As the Universe ages, it continues to gravitate, form stars, and expand. And yet, all this will someday end. Do we finally understand how?
From here on Earth, looking farther away in space means looking farther back in time. So what are distant Earth-watchers seeing right now?
An astronaut stands proudly on the moon's surface near scientific equipment and a lunar lander, as the American flag waves in the background, symbolizing a pioneering USA nation.
As October begins, thousands of longtime NASA employees are leaving the agency. 4000+ will exit by January 9, 2026, changing NASA forever.
a black background with circles and a star in the center.
Proposed over 2000 years ago by Democritus, the word atom literally means uncuttable. Revived in 1803, today's "atoms" can indeed be split.
A diagram illustrating one of the biggest mysteries: the origin of the universe, from the Big Bang and inflation to today, showing the formation of atoms, stars, galaxies, and the ongoing expansion of space.
From the Big Bang to a prior period of cosmic inflation, our cosmic origins are clearer than ever. Yet these 5 big mysteries still remain.
A circular diagram illustrating the observable universe, showing planets, stars, galaxies, and cosmic background radiation layers—revealing where Big Bang echoes still linger.
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?
black hole
All of the matter that we measure today originated in the hot Big Bang. But even before that, and far into the future, it'll never be empty.
planck temperature polarization
The hot Big Bang is often touted as the beginning of the Universe. But there's one piece of evidence we can't ignore that shows otherwise.
As we gain new knowledge, our scientific picture of how the Universe works must evolve. This is a feature of the Big Bang, not a bug.
most distant
The universe is filled with unlikely events, but it is also full of ways to fool ourselves.
A woman sits at a desk covered with tall stacks of papers, reviewing and pointing to documents as she conducts a purpose-driven peer review in a busy office setting.
Just because a paper passes peer review doesn't mean that what's written, or what the author asserts, is true. Here's why it still matters.
Multiplication table from 1 to 20, featuring pythagorean runs and perfect squares highlighted in yellow along the diagonal from top left (1) to bottom right (400).
It's not just an odd quirk of numbers that makes it true, but a deep mathematical insight that dates all the way back to Pythagoras.
LIGO Livingston
10 years ago, LIGO first began directly detecting gravitational waves. Now better than ever, it's revealing previously unreachable features.
ESO milky way
Questions about our origins, biologically, chemically, and cosmically, are the most profound ones we can ask. Here are today's best answers.