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.

No civilization, no matter how successful, can last forever. What does the non-detection of intelligent aliens mean for our own longevity?
A view of a star-filled night sky with numerous bright stars and distant galaxies, including Hubble-dark galaxy formations, scattered across a dark background.
The discovery of CDG-2, a galaxy that's more than 99.9% dark matter, could reveal a new population of ultra-faint galaxies. But is it real?
Voyager
No human has ever left the Solar System, and only six already-launched spacecraft will ever exit it. Will Voyager 1 remain the most distant?
black hole
Quantum entanglement links information between particles across space and time. So what happens when one of them falls into a black hole?
A radio telescope observes a distant galaxy; insets show a magnified view of the galaxy—home to the most distant laser—and a spectral graph. Illustration attributed to IDIA.
Forget about the terawatt lasers we're making on Earth. The Universe makes natural ones thousands of times more powerful than the Sun.
hubble tension
Even space and time are relative in Einstein's universe. That means our old notions of "where" and "when" no longer apply on cosmic scales.
A satellite with extended accordion-like solar panels or reflectors, possibly supporting AI data centers in space, orbits above Earth, with the planet’s surface visible in the background.
There are plenty of engineering obstacles, and those can be overcome. But you cannot change the laws of physics, and those matter too.
The fundamental building blocks of reality are indivisible: quanta that cannot be split or divided. Our understanding remains incomplete.
White lines intersect around a central, glowing sphere on a black background, creating a complex geometric and abstract pattern that suggests how nothing can persist when the universe dies.
Long after the last star burns out, the Universe will experience its end state: a heat death. Will everything prior then be meaningless?
quark gluon plasma primordial soup
Before we formed stars, atoms, elements, or even got rid of our antimatter, the Big Bang made neutrinos. And we finally found them.
Illustration of ape to human evolution with skeletal figures, labeled amino acids, and colorful dots representing molecular structures, highlighting metabolism and the origin of life on Earth.
A big open question in 21st-century science is how life began here on Earth. The metabolism-first scenario just might be the best one.
From the vastness of space, Earth at night reveals its exo-earth beauty, with illuminated continents showcasing a tapestry of lights across North and South America. Major cities and regions emerge from the glowing darkness, painting a vivid picture against the backdrop of oceans.
One big goal of science is to find an inhabited, Earth-like planet. But if we find an Earth-like world, will we even recognize it?
Stellar explosion
Many reactions emit energy, often in large amounts, but cosmic efficiency is another metric altogether. Here's how to maximize your output.
Visualization of the timeline of the universe, from the beginning big bang to the present.
The Universe is expanding, the expansion is accelerating, and some galaxies even recede faster-than-light. Can we see a change in real time?
einstein
Even the most brilliant mind in history couldn't have achieved all he did without significant help from the minds of others.
A luminous dying sun with jets and swirling clouds appears at the center of a dark background, encircled by concentric patterns—an image reminiscent of Hubble’s stunning cosmic view.
Before Sun-like stars die, they transition from AGB red giants into preplanetary nebulae. Here's how Hubble sees the famous Egg Nebula.
Carl Sagan's baloney detection kit taught us how to separate good science from the work of charlatans. In 2026, that matters more than ever.
Silhouette of NASA's Europa Clipper spacecraft with antennas poised against a colorful planetary surface, sparking dreams of alien life.
No claim has even made it halfway up the Confidence of Life Detection (CoLD) scale, but 21st century science is just beginning to unfold.
Side-by-side comparison of the Pillars of Creation in space, showing Hubble's visible light image and JWST's infrared image. Labels indicate "Hubble (Visible)" and "JWST (Infrared)".
Here in our modern Universe, it's cosmic dust that forms planets, complex molecules, and enables life. But how did the Universe create it?
star vs planet vs brown dwarf
13.8 billion years have passed since the Big Bang, but many stars will survive for longer than that. What's the longest-lived a star can be?