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Big Bang Theory
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?
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.
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?
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 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?
In all the Universe, only a few particles are eternally stable. The photon, the quantum of light, has an infinite lifetime. Or does it?
The Universe is 13.8 billion years old, going back to the hot Big Bang. But was that truly the beginning, and is that truly its age?
The "first cause" problem may forever remain unsolved, as it doesn’t fit with the way we do science.
From before the Big Bang to Voyager 1, particle physicist Harry Cliff takes us on a whiz-bang tour of the Universe's evolution.
In the infant Universe, particle physics reigned supreme.
You can only create or destroy matter by creating or destroying equal amounts of antimatter. So how did we become a matter-rich Universe?
Because of dark energy, distant objects speed away from us faster and faster as time goes on. How long before every galaxy is out of reach?
Ground-based facilities enable the greatest scientific production in all of astronomy. The NSF needs to be ambitious, and it's now or never.
The Multiverse fuels some of the 21st century's best fiction stories. But its supporting pillars are on extremely stable scientific footing.
To Fred Hoyle, the Big Bang was nothing more than a creationist myth. 75 years later, it's cemented as the beginning of our Universe.
JWST has puzzled astronomers by revealing large, bright, massive early galaxies. But the littlest ones pack the greatest cosmic punch.
When cosmic inflation came to an end, the hot Big Bang ensued as a result. If our cosmic vacuum state decays, could it all happen again?
There are plenty of life-friendly stellar systems in the Universe today. But at some point in the far future, life's final extinction will occur.
The second law of thermodynamics tells us that entropy always increases. But that doesn't mean it was zero at the start of the Big Bang.
The Universe didn't begin with a bang, but with an inflationary "whoosh" that came before. Here are the biggest questions that still remain.
It took 9.2 billion years of cosmic evolution before our Sun and Solar System even began to form. Such a small event has led to so much.
Early on, only matter and radiation were important for the expanding Universe. After a few billion years, dark energy changed everything.
Our own galaxy, the Milky Way, is both completely normal and absolutely remarkable in a number of ways. Here's the story of our cosmic home.
Millennia ago, philosophers like Anaximander grasped that nature is the ultimate recycler.
On the largest cosmic scales, galaxies line up along filaments, with great clusters forming at their intersection. Here's how it took shape.
Astronomers claim to have found structures so large, they shouldn't exist. With such biased, incomplete observations, perhaps they don't.