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Cosmology
It's the Universe's ultimate chicken-and-egg question: what came first, the galaxy or the black hole? One Little Red Dot proves the answer.
Many people, now with LLM assistance, regularly claim to discover game-changing revolutions. Scientists don't buy it. You shouldn't either.
At and beyond the current frontiers of knowledge, many physicists have strongly held opinions. Can surveys point the way to breakthroughs?
The original idea of the Big Bang was synonymous with a singularity: a point of zero volume. In this Universe, things never got that small.
Astronomers study our cosmic history through stellar and galactic archaeology. But we can't conduct archaeology in space. At least, not yet.
Today, in the here-and-now, a full 13.8 billion years have elapsed since the start of the hot Big Bang. But would that be true for everyone?
Messier 77 is one of the largest nearby spiral galaxies, with an active, brilliant core. Here's what JWST's incomparable eyes saw inside it.
Only nearby objects appear to the naked eye. With telescopes of all types, especially in space, we've smashed those records many times over.
There's a lot of room in interplanetary, interstellar, and intergalactic space, but just how low the densities go is truly mind-boggling.
The first colliding galaxy cluster to reveal dark matter, empirically, turns 20 this year. Here's why it cements dark matter's existence.
On cosmic scales, only dark matter (or something equivalent) gives us the Universe we observe. Now, the Sunyaev-Zel'dovich effect agrees.
"Color" with respect to the strong force is just an analogy. Here's how to understand it without colors, group theory, or any advanced math.
One parameter, alone, sets the dividing line between rocky planets, gas giants, brown dwarfs, stars, and much more. Here's why mass matters.
The distance ladder and the CMB give incompatible values for the expansion rate. A new study shows just how robust the Hubble tension is.
As light travels across the Universe, it's subject to cosmic expansion, changing fields, and relative motion. How about gravitational waves?
Is dark energy evolving with at least 99.99% confidence? Despite the quality of recent data, scientists have every reason to be skeptical.
In a 13.8 billion year old Universe, a few seconds hardly seems like it matters. But these minuscule changes sure do add up over time.
Most massive galaxies are spiral or elliptical shaped. But peculiar galaxies showcase the beautiful violence that helps explain our cosmos.
Early on, the Universe needed near-perfect flatness, or atoms, stars, and galaxies couldn't form. What happens once dark energy takes over?
The image you're seeing isn't a hole in the Universe, and the cosmic voids that do exist aren't hole-like at all.
1hr 16mins
NASA astronomer Michelle Thaller makes the case that quantum entanglement may be the underlying fabric from which spacetime itself emerges.
We have two descriptions of the Universe that work perfectly well: general relativity and quantum physics. Too bad they don't work together.
No matter what physical system we consider, nature always obeys the same fundamental laws. Must it be this way, and if so, why?
When what we predict and what we measure don't add up, that's a sign there's something new to learn. Could it be a new fundamental force?
Over billions of years, fewer stars form, galaxies mutually recede, and the Universe becomes ever darker. Here's how fast it all happens.
Not everyone accepts the scientific consensus; some even make careers out of challenging it. But only a select few do it the right way.
Resembling a cosmic brain, the Exposed Cranium Nebula instead shows a dying, massive star, as JWST reveals. Its fate remains uncertain.
In traveling through the expanding Universe, particles slow down while light and gravitational waves redshift. What degrades and what won't?
1hr 19mins
Theoretical physicist Jim Al-Khalili explores why our sense of time may be incredibly misleading, including the idea that past, present, and future might all exist at once.
The discovery of CDG-2, a galaxy that's more than 99.9% dark matter, could reveal a new population of ultra-faint galaxies. But is it real?