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.

gravitational wave effects on spacetime
We've now detected hundreds of gravitational waves with LIGO, Virgo, and KAGRA. What if we tried Weber's original method in the modern day?
terraforming
The first world beyond Earth for human habitability should be the Moon, not Mars. This is why we should terraform our lunar neighbor first.
two particles different wavelength speed of light
Times dilate and lengths contract near the speed of light. Bizarre and confusing? Sure. But under relativity, it can't be any other way.
A field of galaxies in deep space, featuring a bright spiral galaxy at the lower right with a stellar stream escaping the galaxy, and a large, bright red star at the upper left.
Stellar streams are faint trails of stars that appear to "stream" out of galaxies. A new one, escaping galaxy M61, may point to many others.
Three side-by-side images show different views of the Red Spider Nebula in space, captured by JWST, with a bright center and colorful gases in orange, green, and blue against a backdrop of stars.
When dying, Sun-like stars have binary companions, spectacular sights arise from the ionization. JWST spots the Red Spider Nebula in action!
big crunch
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!