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Dark Matter
Neutrinos are still the most mysterious particle we know of
Nearly 100 years after being theorized, the strange behavior of the neutrino still mystifies us. They could be even stranger than we know.
Ask Ethan: Why couldn’t the Universe have expanded forever?
For 13.8 billion years, the Universe has been expanding. But that couldn't have been the case for an eternity, and science has proven it.
5 undeniable, truthful facts about dark matter
Dark matter has never been directly detected, but the astronomical evidence for its existence is overwhelming. Here's what to know.
We still don’t know how “hot” the hot Big Bang was
We've long known we can't go back to infinite temperatures and densities. But the hottest part of the hot Big Bang remains a cosmic mystery.
Ask Ethan: How and when will the Universe die?
As the Universe ages, it continues to gravitate, form stars, and expand. And yet, all this will someday end. Do we finally understand how?
The argument against the existence of a Theory of Everything
The Holy Grail of physics is a Theory of Everything: where a single equation describes the whole Universe. But maybe there simply isn't one?
Ask Ethan: Could “positive geometry” unlock the theory of everything?
Since even before Einstein, physicists have sought a theory of everything to explain the Universe. Can positive geometry lead us there?
New theory: Could early, supermassive stars explain the Universe?
With several seemingly incompatible observations, cosmology faces many puzzles. Could early, supermassive stars be the unified solution?
No, theoretical physics isn’t broken; it’s just very hard
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.
See the best night sky images from Capture the Dark 2025
Across planet Earth, dark and pristine night skies are an increasingly rare resource. These photos showcase the best of what we still have.
Laniakea, our home supercluster, is already being torn apart
On the largest scales, galaxies don't simply clump together, but form superclusters. Too bad they don't remain bound together.
Ask Ethan: Did our Universe really arise from nothing?
The Big Bang was hot, dense, uniform, and filled with matter and energy. Before that? There was nothing. Here's how that's possible.
What we’ve learned after 35 years of NASA’s Hubble
When the Hubble Space Telescope first launched in 1990, there was so much we didn't know. Here's how far we've come.