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Dark Matter
Since even before Einstein, physicists have sought a theory of everything to explain the Universe. Can positive geometry lead us there?
With several seemingly incompatible observations, cosmology faces many puzzles. Could early, supermassive stars be the unified solution?
The Universe isn't just expanding; the expansion is accelerating. If different methods yield incompatible results, is dark energy evolving?
When you don't have enough clues to bring your detective story to a close, you should expect that your educated guesses will all be wrong.
On the largest scales, galaxies don't simply clump together, but form superclusters. Too bad they don't remain bound together.
The Big Bang was hot, dense, uniform, and filled with matter and energy. Before that? There was nothing. Here's how that's possible.
When the Hubble Space Telescope first launched in 1990, there was so much we didn't know. Here's how far we've come.
The relic signal that first proved the Big Bang has been known and analyzed for 60 years. Join us at the frontiers of modern cosmology!
In just its first 10 hours of observations, the Vera Rubin observatory discovered more than 2000 new asteroids. What else will it teach us?
Is the Universe's expansion rate 67 km/s/Mpc, 73 km/s/Mpc, or somewhere in between? The Hubble tension is real and not so easy to resolve.
The tiniest galaxies of all are the most severely dominated by dark matter. Could black holes be the cause of the extra gravity instead?
If you want to understand the Universe, cosmologically, you just can't do it without the Friedmann equation. With it, the cosmos is yours.
For decades, astronomers have claimed the Milky Way will merge with Andromeda in ~4 billion years. Here's why, in 2025, that seems unlikely.
In our Universe, dark matter outmasses normal matter by a 5-to-1 ratio, shaping the Universe as we know it. What if it simply weren't there?
The long-elusive neutrino was shown to have a bizarre property no one expected: mass. New, tightest-ever limits have profound implications.
If it weren't for the intricate rules of quantum physics, we wouldn't have formed neutral atoms "only" ~380,000 years after the Big Bang.
With stars, gas, and dark matter, galaxies come in a great array of sizes. This new one, Ursa Major III/UNIONS 1, is the smallest by far.
It took nearly 400,000 years, after the Big Bang, to first form neutral atoms. The imprints from that early time can now be seen everywhere.
The laws of nature are almost perfectly symmetric between matter and antimatter, and yet our Universe is made ~100% of matter only. But why?
25 years ago, our concordance picture of cosmology, also known as ΛCDM, came into focus. 25 years later, are we about to break that model?
Large, massive, rotating galaxies like the Milky Way are common today. So how could one form a mere ~2 billion years after the Big Bang?
One of the most promising dark matter candidates is light particles, like axions. With JWST, we can rule out many of those options already.
From the tiniest subatomic scales to the grandest cosmic structures of all, everything that exists depends on two things: charge and mass.
Dark matter doesn't absorb or emit light, but it gravitates. Instead of something exotic and novel, could it just be dark, normal matter?
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?
Historically, astronomers have often named things creatively, bizarrely, and often inaccurately. But which terms are the most egregious?
Here in our Universe, both normal and dark matter can be measured astrophysically. But only normal matter can collapse. Why is that?
First discovered in the mid-1960s, no cosmic signal has taught us more about the Universe, or spurred more controversy, than the CMB.
Scientists just viewed one of the tiniest, most isolated, lowest-mass galaxies ever found with JWST. Despite all odds, it's still growing.
In the year 2000, physicists created a list of the ten most important unsolved problems in their field. 25 years later, here's where we are.