Cosmic Inflation

Cosmic Inflation

Known as the "past hypothesis" problem, the Universe's initially low entropy has long puzzled scientists. Now, cosmic inflation solves it.
Two peculiar galaxies collide in deep space, forming bright clusters and swirling dust clouds—a striking scene that reveals the beauty and violence of the cosmos against a dark background.
Most massive galaxies are spiral or elliptical shaped. But peculiar galaxies showcase the beautiful violence that helps explain our cosmos.
Looking up at the night sky gives us a glimpse of the Universe beyond our terrestrial concerns. Here's the science of what's out there.
travel straight line
In theory, the fabric of space could have been curved in any way imaginable. So why is the Universe flat when we measure it?
warm-hot intergalactic medium sculptor wall
In traveling through the expanding Universe, particles slow down while light and gravitational waves redshift. What degrades and what won't?
particle physics destroy universe
Smashing things together at unprecedented energies sounds dangerous. But it's nothing the Universe hasn't already seen, and survived.
quark gluon plasma primordial soup
Before we formed stars, atoms, elements, or even got rid of our antimatter, the Big Bang made neutrinos. And we finally found them.
Side-by-side comparison of the Pillars of Creation in space, showing Hubble's visible light image and JWST's infrared image. Labels indicate "Hubble (Visible)" and "JWST (Infrared)".
Here in our modern Universe, it's cosmic dust that forms planets, complex molecules, and enables life. But how did the Universe create it?
laniakea
When objects are gravitationally bound, they cannot escape from one another's influence. How does that work within the expanding Universe?
A field of distant galaxies in space with a blue-tinted, magnified section highlighting a single bright celestial object observed by JWST, possibly rich in oxygen.
In a galaxy less than 300 million years after the Big Bang, oxygen's presence abounds. That's expected; its absence would truly be profound.
how many planets
There will always be "wolf-criers" whose claims wither under scrutiny. But aliens are certainly out there, if science dares to find them.
cosmic rays
Particles are everywhere, including particles from space that stream through the human body. Here's how they prove Einstein's relativity.
An artist's impression of an ultra high energy cosmic ray.
The highest-energy particles could be a sign of new, unexpected physics. But the simplest, most mundane explanation is particularly iron-ic.
JADES galaxies
While humanity has been skywatching since ancient times, much of our cosmic understanding has come about only recently. Very recently.
A nebula in space glows with bright purple, pink, and blue hues, surrounded by stars and cosmic dust where new stars form in our expanding universe.
Our Universe doesn't just expand and cool, but the expansion itself is accelerating. Can stars form under such structure-erasing conditions?
A diagram illustrating one of the biggest mysteries: the origin of the universe, from the Big Bang and inflation to today, showing the formation of atoms, stars, galaxies, and the ongoing expansion of space.
Our Standard Model of the Universe, for both particle physics and cosmology, remains intact for now. When will its foundations crack?
Illustration depicting cosmic evolution from the Big Bang, through inflation and CMB, to the large-scale cosmic web. As time advances from 0 to 13.8 billion years, SPHEREx's mapping of galaxies teaches what CMB can't about our universe's development.
Science has assembled an incredible story outlining our Universe's whole history. Despite its unrivaled success, 9 profound gaps remain.
el gordo JWST rotated cropped
Although American Thanksgiving only comes once a year, the scientific rules that make our Universe possible are always worth appreciating.
A vast starry sky showcases a spinning galaxy, a relic from 12 billion years ago, among countless stars of varying brightness on a dark background.
For over 10 billion years, the cosmic star-formation rate has been dropping and dropping. Someday, the final star in the Universe will die.
gravitational wave effects on spacetime
We've now detected hundreds of gravitational waves with LIGO, Virgo, and KAGRA. What if we tried Weber's original method in the modern day?
big bang
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.
A dense cluster of differently sized red, blue, and green spheres overlaps against a black background, evoking the biggest mysteries surrounding the origin of the universe.
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.
Artistic illustration depicting one of the biggest mysteries of the origin of the universe, showing entangled particles connected by curved paths in space, inspired by concepts from quantum physics and wormholes.
Inflation's two main criticisms, that it can predict anything and that the "measure problem" remains unsolved, can't erase its successes.
A diagram illustrating one of the biggest mysteries: the origin of the universe, from the Big Bang and inflation to today, showing the formation of atoms, stars, galaxies, and the ongoing expansion of space.
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.
planck temperature polarization
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.
ESO milky way
Questions about our origins, biologically, chemically, and cosmically, are the most profound ones we can ask. Here are today's best answers.
A dense star field with dark, irregular dust clouds—where cosmic dust come from—obscures parts of the glowing stars in the Milky Way.
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.
As we look to larger cosmic scales, we get a broader view of the expansive cosmic forest, eventually revealing the grandest views of all.