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Universe Expansion
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.
Coming from just 280 million years after the Big Bang, or 98% of cosmic history ago, this new, massive galaxy is a puzzle, but not a mirage.
If all massive objects emit Hawking radiation, not just black holes alone, then everything is unstable, even the Universe. Can that be true?
There's an old saying that "what you see is what you get." When it comes to the Universe, however, there's often more to the full story.
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.
NASA astrophysics, which gave us Hubble, JWST, and so much more, faces its greatest budget cut in history. All future missions are at risk.
The fact that our Universe's expansion is accelerating implies that dark energy exists. But could it be even weirder than we've imagined?
The laws of physics obey certain symmetries and defy others. It's theoretically tempting to add new ones, but reality doesn't agree.
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 COSMOS-Web survey is now complete, combining JWST and Hubble infrared data. Its spectacular views show us the Universe as never before.
Since 1998, we've known our Universe isn't just expanding, but the expansion is accelerating. Could the Big Bang itself be the reason why?
There are limits to where physics makes meaningful predictions: beyond the Planck length, time, or energy. Here's why we can't go further.
All stars shine due to an internal source of energy. Usually, it's nuclear fusion: converting mass into energy. What makes them most bright?
Photons come in every wavelength you can imagine. But one particular quantum transition makes light at precisely 21 cm, and it's magical.
According to Stephen Hawking, spontaneously emitted radiation should cause all black holes to decay. But we've never seen it: not even once.
Empty space itself, the quantum vacuum, could be in either a true, stable state or a false, unstable state. Our fate depends on the answer.
Perhaps no existential question looms larger than that of our ultimate cosmic origins. At long last, science has provided the answers.
The Hubble Space Telescope, launched in 1990, was originally seen as a colossal mistake. This one image, taken in 1995, changed everything.
The most famous Hubble images show glittering stars and galaxies amidst the black backdrop of space. But more was captured than we realized.
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?
Exoplanets can exist anywhere around their parent stars, even so close that they evaporate or disintegrate. Even the rocky ones.
It's difficult to project a sphere onto a flat, two-dimensional surface. All maps of the Earth have flaws; the same is true for the cosmos.
We understand many things about our Universe, and our home within it, extremely well. The number of stars in the Milky Way isn't among them.
Common knowledge says the maximum size of a PDF is as big as 40% of Germany — but that’s a gross underestimate.
The Multiverse isn't just a staple of science fiction; there's real-life science behind it, too. Here are 10 facts to expand your mind.
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?
Over a century after we first unlocked the secrets of the quantum universe, people find it more puzzling than ever. Can we make sense of it?
DESI, by mapping galaxies, has claimed they see evidence for dark energy evolving by getting weaker. But that's only one interpretation.
Someday, we'll look back and see a young galaxy forming stars for the first time. JADES-GS-z14-0, the farthest ever, isn't early enough.
Einstein's general relativity has reigned supreme as our theory of gravity for over a century. Could we reduce it back down to Newton's law?