Ethan Siegel

Ethan Siegel

Theoretical astrophysicist and science writer

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 colorful nebula with a bright center and symmetrical, wing-like clouds of gas and dust extends outward in space, as seen in a JWST reveal that uncovers stars and galaxies in the universe beyond.
Many facts are well-known to professionals, but are unappreciated or even rejected outright by the public. "How stars work" takes the cake.
universe bulk volume brane dimension
For decades, theorists have been cooking up "theories of everything" to explain our Universe. Are all of them completely off-track?
Antimatter rocket with a glowing blue exhaust travels through deep space, showcasing the marvels of interstellar travel amid distant galaxies and stars.
Our dream of journeying to other star systems has a big obstacle to overcome: the vast interstellar distances. Can antimatter get us there?
Image of a galaxy cluster with bright yellow galaxies at the center, surrounded by blue regions representing dark matter in deep space—a striking view often used for dark matter cosmic test MOND studies.
On cosmic scales, only dark matter (or something equivalent) gives us the Universe we observe. Now, the Sunyaev-Zel'dovich effect agrees.
Colorful nebula with bright stars ignite glowing gas clouds in space, featuring red, yellow, and blue hues against a dark background.
Although a star's "birth" is well-defined, it doesn't correspond to an ignition event in its core. Here's how stars are actually born.
protoplanetary disk
Every time a new star forms, there's an opportunity to form planets alongside and around it. How does it happen, and how long does it take?
An Ishihara color blindness test with colored dots, showing letters “u” and “d” in black, and a magnified section highlighting the dot pattern—inviting viewers to observe proton decay through subtle visual cues.
"Color" with respect to the strong force is just an analogy. Here's how to understand it without colors, group theory, or any advanced math.
A hexagonal storm formation with a dark central vortex on a planet’s surface, showing swirling blue and tan cloud patterns.
From 2004 through 2017, Saturn was imaged many times and from many angles up close by Cassini. This new viral image isn't real; it's AI.
A bright, circular object with concentric rings and a surrounding halo set against a dark background, resembling a gap-clearing planet or other astronomical phenomena.
One parameter, alone, sets the dividing line between rocky planets, gas giants, brown dwarfs, stars, and much more. Here's why mass matters.
Two highways, "Early Route" and "Late Route," marked 67.2 and 73.5, traverse a cosmic background with gradients and data—highlighting the Hubble tension and potential bad measurement in determining universal expansion rates.
The distance ladder and the CMB give incompatible values for the expansion rate. A new study shows just how robust the Hubble tension is.
A distorted galaxy with two bright, horizontal bands and scattered stars, seen against a dark background. Image credit: NASA/ESA/CSA.
By looking at a giant, remarkable, edge-on protoplanetary system, astronomers have found a proto-protoplanet for the first time.
Four people wearing black shirts and eclipse glasses look up at the camera indoors, their excitement echoing the spirit of the Artemis II distance record mission.
Human beings have now traveled farther from Earth than ever before with Artemis II's flyby of the lunar far side. Here's how it happened.
Known as the "past hypothesis" problem, the Universe's initially low entropy has long puzzled scientists. Now, cosmic inflation solves it.
apollo 8 earthrise
As the world teeters on the brink of nuclear war, distant, advanced civilizations would never know it. Earth appears peaceful from far away.
A labeled illustration shows the Large Magellanic Cloud, astronomers' most pristine star (SDSS J0715-7334), and the Milky Way galaxy connected by a wispy trail.
The 1st generation of stars formed, lived, and died very early on. But 2nd generation stars could still persist today. Did we just find one?
A person’s silhouette looks out a spacecraft window at Earth—a blue and white sphere against the darkness of space—reflecting the hope inspired by Artemis II’s journey to the moon.
As humanity journeys to the Moon for the first time since 1972, can we rediscover our shared responsibilities: to the world and each other?
black hole merger
As light travels across the Universe, it's subject to cosmic expansion, changing fields, and relative motion. How about gravitational waves?
moon landing Apollo 11
Even though no human has stepped foot on the Moon's surface in 50 years, the evidence of our presence there remains unambiguous.
A colorful map shows the distribution of nearby galaxies, with distances and redshift factors labeled, created by DESI; NSF, NOIRLab, and Kitt Peak logos are visible.
Is dark energy evolving with at least 99.99% confidence? Despite the quality of recent data, scientists have every reason to be skeptical.
Digital illustration showing a large sphere with red dots and data labels, referencing kessler syndrome, accompanied by close-up insets and smaller circular and linear patterns on the right side.
We’ve populated low-Earth orbit with satellites in record time — now we have to figure out how to keep it safe.