An entire Universe in an atom

💥 The building blocks of reality aren't nearly as simple as they seem.

Jun 20, 2026

with Ethan Siegel • June 20, 2026

Greetings readers,

I’ve been away at the American Astronomical Society’s annual summer meeting this past week, and I’ve had some exciting new stories and scoops that have already been reported on, with several more to come. It’s always worth being humble about what you know and open to new information that could not only add to what you previously understood, but that may even revolutionize or overturn what you previously thought was true. It is not a failing to make mistakes or to think things that you later discover need correction. It is part of the process of learning and discovery, and one that scientists must engage in all the time.

There’s still a lot of debate over the nature of JWST’s “little red dots,” and while the idea of “black hole stars,” or black holes that are masquerading as populations of stars, remains popular, many rightfully point out that a single explanation doesn’t work well for each and every object, and that multiple other scenarios should be considered. But we don’t yet know which ones are valid! Beyond that, the JWST focuses light and stays focused, even when viewing objects located at vastly different cosmic distances. A white dwarf was just spotted with beryllium and boron in its atmosphere, and while that’s evidence that it devoured something, no one is quite sure just what it was that got eaten.

We also took a look at the entirety of our cosmic history, as illustrated in just a single image (that makes a beautiful poster), and got to tell an amazing story about how, if you look in the right way at the right scales, pretty much the entire Universe is encoded and discoverable simply by examining a single atom. I learned so much this past whirlwind of a week at one of my favorite professional astronomy conferences, and I’m so excited to bring more and more of it to you in the time that lies ahead. Onward, and deeper into the Universe we go!

All the best,
Ethan

QUANTUM RABBIT HOLE

How a single atom contains the entire quantum Universe

In many ways, the quest for what’s truly fundamental is the story of probing the Universe on ever-smaller scales and at ever-higher energies. By going inside the atom, we uncovered the atomic nucleus, the protons and neutrons within it, and ultimately the quarks and gluons inside them. Along the way, we revealed the elementary building blocks of reality and the rules that bind them together to create the Universe we know today.

The most overlooked fact about JWST’s little red dots

By peering deeper into the distant Universe than ever before, JWST was expected to reveal ultra-distant galaxies. What astronomers didn’t expect was the abundance of bright, compact, red objects known as “little red dots.” While several factors may explain their unusual properties, they still appear to contain too many stars at such early times. But one often-overlooked fact about the early Universe may change that picture entirely, forcing us to rethink what these mysterious objects really are.

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ASK ETHAN

Ask Ethan: How do space telescopes stay focused?

The largest, latest, and greatest space telescope in humanity’s arsenal for learning about the Universe is the James Webb Space Telescope (JWST). It observes everything from worlds in our own Solar System to galaxies billions of light-years away, all while maintaining extraordinary precision. But how do scientists focus a telescope with moving parts operating in the harsh environment of space, and keep it focused over time? It’s a remarkable feat of engineering, and the answer is more fascinating than you might think.

If you have a burning question about the Universe,
email startswithabang@gmail.com!

THROUGH SPACE AND TIME

A single illustration reveals the entirety of cosmic history

It wasn’t until the late 20th century that we learned what our Universe is made of, how old it is, and how it began: with cosmic inflation ending and giving rise to the hot Big Bang 13.8 billion years ago. Today, we can reconstruct the Universe’s history in remarkable detail, from our Solar System to the largest cosmic structures. Through the power of art, that entire story, from before the Big Bang to the distant future, can now be captured in a single image. It’s worth far more than a passing glance.

Rarest elements reveal planets eaten by white dwarfs

Probing the absorption lines of a star or stellar remnant can reveal the composition of its outer layers, but recently accreted material can leave its own chemical fingerprints. Among the rarest elements detected are lithium, beryllium, and boron, with beryllium and boron typically produced together through cosmic spallation in a well-known ratio. In a surprising discovery, astronomers found both elements in the atmospheres of white dwarfs, with abundances greatly enhanced above their usual cosmic abundances and an unexpected ratio. The culprit may be something even more intriguing: a recently devoured planet.

Ethan Siegel, Ph.D., is an award-winning theoretical astrophysicist who's been writing Starts With a Bang since 2008. You can follow him on Twitter @StartsWithABang.

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