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.

first contact
Only 5% of the Universe is made of normal "stuff" like we are. Could there be dark matter or dark energy life, or even aliens, out there?
Diagram illustrating how small fundamental particles are, showing scaling sizes from macroscopic matter to quarks. It details crystal, atom, atomic nucleus, and nucleon sizes in meters, ranging from 10^-9 m to
When we divide matter into its fundamental, indivisible components, are those particles truly point-like, or is there a finite minimum size?
World map showing temperature changes from 1880 to 2024, with warmer regions in red and cooler areas in blue. A timeline runs from 1880 to 2024 at the bottom.
The primary causes of global climate change are all due to human activity. Adding aerosols to our atmosphere only exacerbates the problem.
black hole merger
The ultimate multi-messenger astronomy event would have gravitational waves, particles, and light arriving all at once. Did that just occur?
Astronomical image of a young star system with labeled features: jet, conical outflow, dark lane, possible spiral, disk, tail, and a scale marking 300 astronomical units.
A young, nearby, massive star, whose protoplanetary disk appears perfectly edge-on, was just viewed by JWST, with staggering implications.
Five men, immersed in conversation, sit indoors on a blanket, eating from metal bowls. Despite the cloud of ignorance surrounding them about modern science, they share stories and laughter as a red bowl rests prominently at their center.
If we wish to tackle the very real problems society faces, we require expert-level knowledge. Valuing it starts earlier than we realize.
super earth mini neptune transit spectroscopy
Seeking life beyond the Solar System, we first look to the closest star systems with Earth-like planets. Here's why that's not good enough.
A grayscale image captures the moon's surface, featuring numerous craters of varying sizes. The scene is reminiscent of a lunar Grand Canyon, with a highlighted spot drawing the viewer's attention.
Our Moon is full of craters, basins, and ancient lava flows. But two large lunar Grand Canyons have the same origin: a single, giant impact.
A colorful cosmic scene features a bright super star cluster with glowing stars surrounded by swirling red, orange, blue, and gray nebulous clouds.
There are only four super star clusters in all the Local Group: rarities today. Here's what the youngest, the just-discovered N79, shows us.
warm-hot intergalactic medium sculptor wall
Here in our Universe, both normal and dark matter can be measured astrophysically. But only normal matter can collapse. Why is that?
A textured, abstract artwork prominently features the word "CENSORSHIP" in bold black, flanked by stark words like "BEATEN," "DEATHS," and "IRON FIST." The beige backdrop subtly hints at government influence, blending shadows of science with restraint.
With a flurry of threats to scientists, science funding, and health policy, the USA now faces a crisis reminiscent of Soviet-era Lysenkoism.
Diagram showing the cosmic microwave background radiation with satellites COBE, WMAP, and Planck, illustrating improvements in observational detail and resolution.
First discovered in the mid-1960s, no cosmic signal has taught us more about the Universe, or spurred more controversy, than the CMB.
elements
From LIGO, there weren't enough neutron star-neutron star mergers to account for our heavy elements. With a JWST surprise, maybe they can.
A dark nebula with dimming T Tauri stars nestled among dust and gas. The nebula casts a shadowy silhouette against a backdrop of numerous smaller stars in space.
It's the ultimate game of cosmic "cover up," as the dimming occurs when a circumbinary disk from a nearby star passes in front of T Tauri North.
Illustration of the periodic table with a human silhouette reveals how heaviest elements shape us. Elements are color-coded, depicting the percentage composition of the body: 73% oxygen, 16.5% carbon, 9.5% hydrogen, and 1% others.
Matter is made up largely of atoms, where atomic nuclei can contain up to 100 protons or more. But how were the heaviest elements made?
CMB polarization Planck
Cosmic inflation, proposed back in 1980, is a theory that precedes and sets up the hot Big Bang. After thorough testing, is it still valid?
A dense star field with various galaxies and cosmic bodies scattered, showcasing a vibrant and colorful view of space. Among them, an isolated galaxy grows in brilliance, capturing the imagination with its distant allure.
Scientists just viewed one of the tiniest, most isolated, lowest-mass galaxies ever found with JWST. Despite all odds, it's still growing.
A group of satellite dishes under a starry sky, capturing celestial signals from star birth.
New telescopes, radio dishes, and gravitational wave detectors are needed for next-generation science. Will the USA lead the way?
Three images of the Ring Nebula reveal its true shape: visible light (left), infrared (center), and a composite with contour lines (right) showcasing different details of the nebula's intricate structure.
The Ring Nebula, a bright, circular planetary nebula, is created by a dying Sun-like star. After centuries, we finally know its true shape.
JWST MIRI NIRCam SMACS 0723
Since mid-2022, JWST has been showing us how the Universe grows up, from planets to galaxies and more. So, what's its biggest find of all?