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Universe Expansion
Nearly 100 years after being theorized, the strange behavior of the neutrino still mystifies us. They could be even stranger than we know.
The planet, the Solar System, and the galaxy aren't expanding. But the whole Universe is. So where does the dividing line begin?
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.
Dark matter has never been directly detected, but the astronomical evidence for its existence is overwhelming. Here's what to know.
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.
Found by Hubble before JWST's launch, GNz7q looked like a mix of a galaxy and a quasar. Was it actually our first known "little red dot"?
Observations with the Hubble space telescope helped cement dark energy and reveal the Hubble tension. How are these two things so different?
Inflation's two main criticisms, that it can predict anything and that the "measure problem" remains unsolved, can't erase its successes.
To learn how our Universe grew up, we have to look at large numbers of galaxies at all distances to find out. Good thing we have JWST!
Our Sun only arose after 9.2 billion years of cosmic history: with many stars living and dying first. How many prior generations were there?
Since the time of Galileo, Saturn's rings have remained an unexplained mystery. A new idea may have finally solved the longstanding puzzle.
By deeply imaging a large volume of space, COSMOS-Web provides JWST's widest cosmic views. Its gravitational lenses reveal a big surprise.
As the Universe ages, it continues to gravitate, form stars, and expand. And yet, all this will someday end. Do we finally understand how?
From here on Earth, looking farther away in space means looking farther back in time. So what are distant Earth-watchers seeing right now?
From the Big Bang to a prior period of cosmic inflation, our cosmic origins are clearer than ever. Yet these 5 big mysteries still remain.
If you think of the Big Bang as an explosion, we can trace it back to a single point-of-origin. But what if it happened everywhere at once?
All of the matter that we measure today originated in the hot Big Bang. But even before that, and far into the future, it'll never be empty.
The hot Big Bang is often touted as the beginning of the Universe. But there's one piece of evidence we can't ignore that shows otherwise.
As we gain new knowledge, our scientific picture of how the Universe works must evolve. This is a feature of the Big Bang, not a bug.
The universe is filled with unlikely events, but it is also full of ways to fool ourselves.
Questions about our origins, biologically, chemically, and cosmically, are the most profound ones we can ask. Here are today's best answers.
Dust is ubiquitous in the modern Universe, appearing in nearly all galaxies. But our cosmos was born dust-free. So where does it originate?
It's the origin of our entire observable Universe, but it's still not the very beginning of everything.
In this excerpt from "Facing Infinity," Jonas Enander examines how John Michell conceived of "dark stars," or massive bodies with enough gravity to trap light, all the way back in 1783.
Going back to 1990, we hadn't even found one planet outside of our Solar System. As we close in on 6000, we now see many of them directly.
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?
As we look to larger cosmic scales, we get a broader view of the expansive cosmic forest, eventually revealing the grandest views of all.
The Universe isn't just expanding; the expansion is accelerating. If different methods yield incompatible results, is dark energy evolving?
10 years ago, LIGO saw its first gravitational wave. After 218 detections, our view of black holes has changed forever. Can this era endure?