Size isn’t everything 🔭
💥 This telescope may outperform observatories much larger than itself.
with Ethan Siegel • July 11, 2026
Greetings readers,
Now that we’ve entered the summer months, there are not only plenty of new science developments to bring to your attention, but also Big Think’s brand new quarterly print issue: The Opt-Out Issue, available to all Big Think members. Become one today if you aren’t already! As part of the online version of the issue, I’ve written a piece on whether the U.S. will opt out of the field it helped invent: gravitational wave research, with a story titled “America pioneered gravitational wave research. Now it may leave it behind.” It’s not the only thing that people, institutions, and nations are opting out of, and there’s still hope to maintain the course we initially set and continue advancing it. Let’s advocate for all the right things!
Beyond that, we’ve taken a look at some incredible science stories this week. The beginning of the Universe, before the Big Bang and before cosmic inflation, is something we can only speculate about today; the information that would tell us what actually occurred has already been erased from what we can ever observe. A study came out just a couple of weeks ago claiming that the Universe isn’t the same in all directions: an anisotropic Universe. Unfortunately, that study was fatally flawed, and I’ve got the lowdown on just how they messed up and what the data actually indicates. The smallest of the three big proposed next-generation flagship observatories, the Giant Magellan Telescope (GMT), will turn out to be the best of the three on many fronts, and now you can see why for yourself. The U.S. may have broken records with this year’s July 4th (and 5th) fireworks shows, but we still only pale in comparison to the power generated by our planet’s aurorae.
And finally, if you’ve ever wondered just how we know what the size of the Universe was at any moment in cosmic history, it turns out you’re not alone; that’s the subject of this week’s Ask Ethan! We’ve got a new podcast coming to you next week, and a whole lot more spectacular science on the way as well. Make sure you don’t miss any of it, and I’ll make sure to deliver as much as I can each week as we continue on our cosmic voyage together!
All the best,
Ethan
SMALL BUT MIGHTY
Why the “smallest” giant telescope may be the world’s best
The current generation of the world's largest optical telescopes spans 6.5 to 11 meters in diameter, but the next era belongs to a new class of 25- to 39-meter observatories. While the 39-meter European Extremely Large Telescope is the largest, the 25-meter Giant Magellan Telescope may ultimately outperform them all. Thanks to its clever optical design, fewer reflections, and more efficient instruments, it could become the most powerful telescope of its generation. Here's why.
THE MISSING BEGINNING
Forget seeing the Universe’s beginning. It’s already been erased.
In the original Big Bang model, the expanding Universe could be traced back to a single point: a singularity marking the birth of space and time. But that picture has since been replaced by cosmic inflation, which preceded the hot Big Bang and left observable imprints on our Universe. Unfortunately, inflation also erased nearly all traces of what came before it, leaving only the final tiny fraction of a second within our reach and our ultimate cosmic origins frustratingly out of view.
ASK ETHAN
Ask Ethan: What sets the size of the observable Universe?
Here in our modern cosmos, we often say the Universe is 13.8 billion years old and that the observable Universe extends 46.1 billion light-years in every direction. While the full Universe may be vastly larger, or even infinite, the size of the observable Universe is remarkably well known, not just today but throughout cosmic history. What determines its size, and how do we know it so precisely? The answer is surprisingly straightforward, even in a Universe governed by Einstein's general relativity.
If you have a burning question about the Universe,
email startswithabang@gmail.com!
FALSE ALARM
Famous study in error: the Universe isn’t anisotropic
Although the Universe is clumped into galaxies, galaxy clusters, filaments, and cosmic voids, it should appear uniform on the largest scales. While past hints of large-scale anisotropies have surfaced, they’ve consistently disappeared as better data became available. Now, using data from DESI, two researchers claim to have found evidence that the Universe isn’t the same in every direction. But a closer look reveals their conclusion doesn’t hold up.
LIGHT SHOW
What has more power: Earth’s aurorae or fireworks shows?
While fireworks are often thought of as Earth’s greatest visual spectacle, nature offers an even more dazzling show: the aurora. When charged particles from the Sun are funneled by Earth’s magnetic field into the atmosphere near the poles, they create the Aurora Borealis and Aurora Australis, ranging from faint glows to spectacular outbursts. Even as fireworks displays have shattered records in the 2020s, one question remains: Which produces more power, fireworks or the northern lights?
OPTING OUT
America pioneered gravitational wave research. Now it may leave it behind.
The United States has led gravitational wave research for decades, with LIGO making the first-ever detection in 2015. But that leadership is now at risk. Proposed federal budget cuts threaten LIGO’s future, while the next-generation Cosmic Explorer has received no funding at all. The U.S. doesn’t have to surrender its leadership in this groundbreaking field, but the decisions made now will shape the future of gravitational wave astronomy for decades to come.
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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