Big Bang Theory

Big Bang Theory

A vibrant cosmic scene reveals a galaxy with bright jets of energy, hottest stars twinkling vividly amidst scattered stars against a dark backdrop.
Here in our Universe, stars shine brightly, providing light and heat to planets, moons, and more. But some objects get even hotter, by far.
lookback time galaxies
We see objects whose light only arrives just now. But we see them as they were in the past: when that now-arriving light was first emitted.
Visualization of a section through the large-scale structure of the universe highlighting cosmic web patterns and distributions.
Our Universe isn't just expanding, the expansion is accelerating. Instead of dark energy, could a "lumpy" Universe be at fault?
Bright orange star surrounded by a dense field of smaller white stars in space.
Carl Sagan was far from the first to declare we are the children of ancient stars.
A person in a red shirt stands next to "Waves in an Impossible Sea," the 2024 science book by Matt Strassler. The background displays a blurred bookshelf.
Matt Strassler's journey into fundamental physics culminates in a brilliant explanation of the Higgs field. Enjoy this exclusive interview.
evolution universe cosmic history big bang
From a hot, dense, uniform state in its earliest moments, our entire known Universe arose. These unavoidable steps made it all possible.
lookback time galaxies
For nearly 60 years, the hot Big Bang has been accepted as the best story of our cosmic origin. Could the Steady-State theory be possible?
CMB polarization Planck
Since the mid-1960s, the CMB has been identified with the Big Bang's leftover glow. Could any alternative explanations still work?
heavy neutral atom
There are a few small cosmic details that, if things were just a little different, wouldn't have allowed our existence to be possible.
Bright cosmic explosion with flames and smoke surrounded by stars against a dark, starry background.
Black holes are the most massive individual objects, spanning up to a light-day across. So how do they make jets that affect the cosmic web?
Diagram of the expanding universe concept with cosmic inflation, light cone, and time axis.
Almost everyone asserts that the Big Bang was the beginning of everything, followed by inflation. Has everyone gotten the order wrong?
Friedmann equation
The most common visual depictions of the history of the Universe show the Big Bang as a growing tube with an "ignition" point. Why is that?
Illustration of Mars with overlaid data graphs and lines, offering analytical representations that unravel the mysteries of dark matter.
Watching for changes in the Red Planet’s orbit over time could be new way to detect passing dark matter.
A starry sky with a magnified view highlights an orange, cloud-like structure representing one of the youngest astronomical objects in the Milky Way, shimmering as it subtly rotates.
The earliest Milky Way-like galaxy, REBELS-25, was spotted rotating about its axis. It's only 700 million years old: 5% of our present age.
Planck CMB
Today, the deepest depths of intergalactic space aren't at absolute zero, but at a chill 2.73 K. How does that temperature change over time?
A vibrant, high-resolution image of a spiral galaxy with rich clusters of stars and interstellar dust, where most stars formed.
The Universe has been creating stars for nearly all 13.8 billion years of its history. But those photons can't match the Big Bang's light.
Lockman hole galaxy cluster herschel
In all directions, at great distances, the Universe looks younger, more uniform, and less evolved. Does that mean Earth must be the center?
The image shows a bright spot labeled "JADES-GS-z13-1-LA," seemingly an impossible light captured by the JWST, surrounded by measurement markers, including a scale bar for 1 kpc and 0.28 arcsec. Filters and colors are listed at the bottom.
The Lyman-α emission line has never been seen earlier than 550 million years after the Big Bang. So why does JADES-GS-z13-1-LA have one?
So far, Earth is the only planet that we're certain possesses active life processes. Here's what we shouldn't assume about life elsewhere.
A circular illustration depicting the observable universe with various galaxies, stars, and cosmic structures emanating from a central point, symbolizing the solar system and hinting at how far away the Big Bang occurred.
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?
every square degree
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?
smbh growth evolution from direct collapse seed
Even in the very early Universe, there were heavy, supermassive black holes at the centers of galaxies. How did they get so big so fast?
A black and white particle track image on the left and a colorful representation of a neutrino.
The properties of a ghostly particle called a neutrino are coming into focus.
A graphical representation illustrating the concept of the big bang and the subsequent expansion of the universe, depicted by a transition from a singular point of energy to a wide, grid-like spread of galaxies and celestial elements
On the largest of cosmic scales, the Universe is expanding. But it isn't all-or-nothing everywhere, as "collapse" is also part of the story.
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.