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 no upper limit to how massive galaxies or black holes can be, but the most massive known star is only ~260 solar masses. Here's why.
universe bulk volume brane dimension
In the year 2000, physicists created a list of the ten most important unsolved problems in their field. 25 years later, here's where we are.
lookback time galaxies
We see objects whose light only arrives just now. But we see them as they were in the past: when that now-arriving light was first emitted.
Visualization of a section through the large-scale structure of the universe highlighting cosmic web patterns and distributions.
Our Universe isn't just expanding, the expansion is accelerating. Instead of dark energy, could a "lumpy" Universe be at fault?
Sunlight, like a quantum sun, streams through tree branches, casting golden rays over a calm lake.
Despite the Sun's high core temperatures, atomic nuclei repel each other too strongly to fuse together. Good thing for quantum physics!
Comparison of two 2025 calendars: the left features a full-page format marked with a red X, while the right showcases a compact one-page calendar highlighted with a green checkmark.
It's simpler, more compact, and reusable from year-to-year in a way that no other calendar is. Here's both how it works and how to use it.
An abstract green fractal pattern resembling interconnected neural pathways on a black background evokes the complexity of a fractal universe.
On larger and larger scales, many of the same structures we see at small ones repeat themselves. Do we live in a fractal Universe?