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Ethan Siegel
Theoretical astrophysicist and science writer
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.
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The CMB has long been considered the Big Bang's "smoking gun" evidence. But after what JWST saw, might it come from early galaxies instead?
Once every 12 years, Earth, Jupiter, Uranus, and Neptune all line up, opening a window for a joint mission. Our next chance arrives in 2034.
Over the first half of 2025, the US has cut science as never before. This disaster for American science may be a gift to the rest of the world.
Originally, the abundance of bright, early galaxies shocked astronomers. After 3 years of JWST, we now know what's really going on.
Looking at a dark, night sky has filled humans with a sense of awe and wonder since prehistoric times. But appearances can be deceiving.
In just its first 10 hours of observations, the Vera Rubin observatory discovered more than 2000 new asteroids. What else will it teach us?
For over 50 years, it’s been the scientifically accepted theory describing the origin of the Universe. It’s time we all learned its truths.
For hundreds of millions of years, a cosmic fog blocked all signs of starlight. At last, JWST found the galaxies that cleared that fog away.
Here in 2025, many of us claim to come to our own conclusions by doing our own research. Here's why we're mostly deluding ourselves.
Massive galaxy cluster Abell S1063, 4.5 billion light-years away, bends and distorts the space nearby. Here's what a JWST deep field shows.
Is the Universe's expansion rate 67 km/s/Mpc, 73 km/s/Mpc, or somewhere in between? The Hubble tension is real and not so easy to resolve.
The ANITA experiment found cosmic rays shooting out of Antarctica. One interpretation claims "parallel Universes," but is that right?
Different methods of measuring the Universe's expansion rate yield high-precision, incompatible answers. But is the problem robustly real?
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 few physical quantities, in all laboratory experiments, are always conserved: including energy. But for the entire Universe? Not so much.
If you want to understand the Universe, cosmologically, you just can't do it without the Friedmann equation. With it, the cosmos is yours.
Viewing Uranus's largest moons with Hubble, astronomers hoped to find darkening on the trailing side. They found the exact opposite instead.
On Earth, our particle accelerators can reach tera-electron-volt (TeV) energies. Particles from space are thousands of times as energetic.
The first galaxies were irregular blobs of gas and stars. But modern features, like spiral arms and bars, appeared earlier than expected.