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.

There's some, but not overwhelming, evidence that dark energy is evolving. What would it take for a "Big Crunch" to be our cosmic fate?
solar system model
Scientists are notoriously resistant to new ideas. Are they falling prey to groupthink? Or are our current theories just that successful?
ufo lights liverpool
Physicist Daniel Whiteson challenges the notion that all intelligent species would eventually uncover the same laws of nature. Do you agree?
DUNE neutrino detectors
Nearly 100 years after being theorized, the strange behavior of the neutrino still mystifies us. They could be even stranger than we know.
An image of El Gordo, a massive galaxy cluster captured by Hubble
The planet, the Solar System, and the galaxy aren't expanding. But the whole Universe is. So where does the dividing line begin?
big bang
For 13.8 billion years, the Universe has been expanding. But that couldn't have been the case for an eternity, and science has proven it.
dark matter
Dark matter has never been directly detected, but the astronomical evidence for its existence is overwhelming. Here's what to know.
A dense cluster of differently sized red, blue, and green spheres overlaps against a black background, evoking the biggest mysteries surrounding the origin of the universe.
We've long known we can't go back to infinite temperatures and densities. But the hottest part of the hot Big Bang remains a cosmic mystery.
star vs planet vs brown dwarf
Red dwarfs are the Universe's most common star type. Their flaring now makes potentially Earth-like worlds uninhabitable, but just you wait.
quasar-galaxy hybrid
Found by Hubble before JWST's launch, GNz7q looked like a mix of a galaxy and a quasar. Was it actually our first known "little red dot"?
Illustration of the universe's large-scale structure with colorful concentric circles, representing cosmic structure distribution, against a black background.
Observations with the Hubble space telescope helped cement dark energy and reveal the Hubble tension. How are these two things so different?
The whole isn't greater than the sum of its parts; that's a flaw in our thinking. Non-reductionism requires magic, not merely science.
A series of solar sail spacecraft harvest solar power at night, floating above Earth's atmosphere with the sun shining in the background.
Solar power has the disadvantage that there's no Sun at night. Satellite startup Reflect Orbital wants to change that, but at what cost?
Artistic illustration depicting one of the biggest mysteries of the origin of the universe, showing entangled particles connected by curved paths in space, inspired by concepts from quantum physics and wormholes.
Inflation's two main criticisms, that it can predict anything and that the "measure problem" remains unsolved, can't erase its successes.
The Orion Nebula surrounded by stars, with a bright green meteor streaking diagonally across the image, evokes the wonder of shooting stars illuminating the night sky.
The Orionids meteor shower peaks October 20th/21st here in 2025, coinciding with a new Moon. See the brightest shooting stars of the year!
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.