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Universe Expansion
If you bring too much mass or energy together in one location, you'll inevitably create a black hole. So why didn't the Big Bang become one?
The Universe is precisely dated at 13.8 billion years old, but astronomers claim the Methuselah star is 14.5 billion years old. What gives?
It's 2024, and we still only know of the fundamental particles of the Standard Model: nothing more. But these 8 unanswered questions remain.
The expanding Universe, in many ways, is the ultimate out-of-equilibrium system. After enough time passes, will we eventually get there?
For nearly 25 years, we thought we knew how the Universe would end. Now, new measurements point to a profoundly different conclusion.
In ~7 billion years, our Sun will run out of fuel and die. So will every star, eventually. Here are the different fates they'll encounter.
The mutual distance between well-separated galaxies increases with time as the Universe expands. What else expands, and what doesn't?
The number of planets that could support life may be far greater than previously thought, a recent discovery suggests.
We normally think of dark matter as the "glue" that holds galaxies and larger structures together. But it's so much more than that.
There are many theories of gravity out there, and many interpretations of wide binary star data. What have we really learned from it all?
The evidence that the Universe is expanding is overwhelming. But how? By stretching the existing space, or by creating new space itself?
In 2017, we detected gold being forged in a neutron star-neutron star merger. Now, in 2024, the amounts created simply don't add up.
The most iconic "dark nebula" of all lights up under JWST's infrared gaze. Here's what's newly discovered inside.
Holograms preserve all of an object's 3D information, but on a 2D surface. Could the holographic Universe idea lead us to higher dimensions?
In general relativity, white holes are just as mathematically plausible as black holes. Black holes are real; what about white holes?
From the earliest stages of the hot Big Bang (and even before) to our dark energy-dominated present, how and when did the Universe grow up?
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Physicist Sean Carroll on entropy, complexity, and the origins of life:
Dark energy is one of the biggest mysteries in all the Universe. Is there any way to avoid "having to live with it?"
In the 20th century, many options abounded as to our cosmic origins. Today, only the Big Bang survives, thanks to this critical evidence.
For some reason, when we talk about the age of stars, galaxies, and the Universe, we use "years" to measure time. Can we do better?
The JWST's observations of well-developed galaxies early in universal history may coincide with accepted astronomical theory after all.
The most common element in the Universe, vital for forming new stars, is hydrogen. But there's a finite amount of it; what if we run out?
Life arose on Earth very early on. After a few billion years, here we are: intelligent and technologically advanced. Where's everyone else?
Total eclipses are a product of a strange and almost eerie cosmic coincidence — one that makes Earth an even rarer world in the galaxy and, by proxy, in the Universe.
Our Universe requires dark matter in order to make sense of things, astrophysically. Could massive photons do the trick?
The Universe is expanding, and the Hubble constant tells us how fast. But how can it be a constant if the expansion is accelerating?
Here's what recent DESI measurements suggest — and why it's too early to update conventional predictions about the Universe's distant future.
In all the Universe, only a few particles are eternally stable. The photon, the quantum of light, has an infinite lifetime. Or does it?
Yes, the Universe is expanding, but if you've ever wondered, "How fast is it expanding," the answer isn't in terms of a speed at all.
Is the Universe finite or infinite? Does it go on forever or loop back on itself? Here's what would happen if you traveled forever.