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 composite image showing a galaxy with red circles marking stars on the left and multicolored expanding rings with Earth on the right, all set against a grid background, illustrating concepts like Hubble tension studied by Wendy Freedman.
Different methods of measuring the Universe's expansion rate yield high-precision, incompatible answers. But is the problem robustly real?
Circular astronomical image showing constellations and celestial objects labeled against a dark sky, reminiscent of a NASA PUNCH video sun corona visualization, with a timestamp of 2025-06-03 01:52 at the bottom left.
Launched in March, the PUNCH mission has viewed two incredible coronal mass ejections, tracking them farther from the Sun than ever before.
The tiniest galaxies of all are the most severely dominated by dark matter. Could black holes be the cause of the extra gravity instead?
A digital illustration showing a glowing blue particle on the left, evoking cosmic inflation, transitioning into a geometric, grid-like structure on a purple background on the right.
A few physical quantities, in all laboratory experiments, are always conserved: including energy. But for the entire Universe? Not so much.
Timeline of the universe from the Big Bang, as described in cosmology, showing inflation, formation of atoms, stars, galaxies, and expansion to the present day over 13.8 billion years.
If you want to understand the Universe, cosmologically, you just can't do it without the Friedmann equation. With it, the cosmos is yours.
A blue planet with visible rings and several small, bright Uranus moons is set against a darkened black background.
Viewing Uranus's largest moons with Hubble, astronomers hoped to find darkening on the trailing side. They found the exact opposite instead.
An illustration shows a cosmic ray entering Earth’s atmosphere, creating a cascade of secondary particles—some of the highest energy particles astronomers study—detected by an array of sensors on the ground.
On Earth, our particle accelerators can reach tera-electron-volt (TeV) energies. Particles from space are thousands of times as energetic.