Big Bang Theory

Big Bang Theory

All telescopes are fundamentally limited in what they can see. JWST reveals more distant galaxies than Hubble, but still can't see them all.
An artist's impression of a cluster of stars.
There was a time where no starlight was visible throughout the entire cosmos. That time was short-lived: shorter than astronomers imagined.
parallel universe
The Universe's history, from cosmic inflation to the Big Bang to the present, is known. But whether it's infinite or not is still a mystery.
universe temperature
Although the Big Bang occurred at an instant in time long ago, we still see the light from it. Will the evidence ever disappear completely?
Two breathtaking pictures of a galaxy and a star taken by the Hubble telescope, highlighting the beauty and cosmic magnitude that fuels the Hubble tension.
There are two different ways to measure the expansion rate of the Universe, and they don't agree. And no, new measurements don't help.
A new all-time record! JWST's discovery of JADES-GS-z14-0 pushes the earliest galaxy ever seen to just 290 million years after the Big Bang.
Abstract representation of a cosmic event with a burst of particles emanating from a central point, blending astrophysical imagery with geometric designs.
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?
A deep space image showing numerous galaxies of different shapes and sizes scattered across a dark background, with many stars and cosmic objects, including the ancient Methuselah star, also visible throughout.
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?
Stellar explosion
The expanding Universe, in many ways, is the ultimate out-of-equilibrium system. After enough time passes, will we eventually get there?
big crunch
For nearly 25 years, we thought we knew how the Universe would end. Now, new measurements point to a profoundly different conclusion.
timeline of the universe history
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
Dark energy is one of the biggest mysteries in all the Universe. Is there any way to avoid "having to live with it?"
universe temperature
In the 20th century, many options abounded as to our cosmic origins. Today, only the Big Bang survives, thanks to this critical evidence.
how many planets
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?
wolf rayet wr 31a
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?
pulse light quantum tunnel barrier
In all the Universe, only a few particles are eternally stable. The photon, the quantum of light, has an infinite lifetime. Or does it?
cosmic epochs lookback hubble 13.8 billion
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?
Abstract representation of a cosmic event with a burst of particles emanating from a central point, blending astrophysical imagery with geometric designs.
The "first cause" problem may forever remain unsolved, as it doesn’t fit with the way we do science.
A bright star illuminates the surrounding space with a spectrum of colors in a nebula.
From before the Big Bang to Voyager 1, particle physicist Harry Cliff takes us on a whiz-bang tour of the Universe's evolution.
A digital image of a star's structure superimposed on a futuristic tunnel with neon arrow accents.
In the infant Universe, particle physics reigned supreme.
anitmatter annihilation
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?
An image of the future of US astronomy with a large telescope inside a building.
Ground-based facilities enable the greatest scientific production in all of astronomy. The NSF needs to be ambitious, and it's now or never.
A black and white image of a bunch of spheres, symbolizing the multiverse concept discussed by scientists.
The Multiverse fuels some of the 21st century's best fiction stories. But its supporting pillars are on extremely stable scientific footing.
Man in a suit posing with a vintage BBC Big Bang 75 microphone.
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.
Fractal pattern with a stark contrast of vibrant orange and deep blue hues, designed to make the universe visible.
JWST has puzzled astronomers by revealing large, bright, massive early galaxies. But the littlest ones pack the greatest cosmic punch.
inflation spawn parallel universes
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?
Planets in varying sizes orbiting around a bright central star in a purple-hued cosmos, where life persists.
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.
A blue t-shirt with a yellow circle and arrow, representing the universe.
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.
A diagram showing the structure of a galaxy.
The Universe didn't begin with a bang, but with an inflationary "whoosh" that came before. Here are the biggest questions that still remain.