Cosmology

Cosmology

A grid of six astronomical images shows different examples of gravitationally lensed quasars, each labeled with its unique identification code and relevant to studies addressing Hubble tension.
The method you use to measure the expanding Universe determines which of two answers you'll get. Lensed supernovae can't resolve that issue.
A large group of people stands together inside a spacious, industrial facility—likely the LHC—surrounded by tall machinery, pipes, and metal structures, celebrating the best 2025 discovery in particle physics.
Some vital, key ingredients must be in place for the Universe to make more matter than antimatter. The LHC took us one step closer in 2025.
An Ishihara color blindness test with colored dots, showing letters “u” and “d” in black, and a magnified section highlighting the dot pattern—inviting viewers to observe proton decay through subtle visual cues.
As the lightest baryon in the Universe, the proton is thought by many to be eternally stable. But if it isn't, can we observe it decaying?
millennium simulation cosmic web slice
We have a picture of how and when it will all come to an end. These three big ideas could still profoundly change how our cosmos evolves.
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.
supermassive black holes
Such massive, early supermassive black holes have puzzled astronomers for decades. At last, we've finally figured out how they form.
A telescope beneath a colorful, abstract visualization of the universe, with a starry night sky in the background.
Every observation out into deep space is also a look back in time.
Book cover of "Crush: Close Encounters with Gravity" by James Riordon, featuring a crushed red soda can with a green leaf.
From white holes to dark stars and multiverses, James Riordon explores the bizarre exhibits of general relativity's "cryptozoo."
flight through universe CEERS JWST NASA
Wavelengths stretch, distances grow, and temperatures cool as the Universe expands with time. How are the various cosmic parameters related?
A jellyfish galaxy with a bright white and yellow core is surrounded by red clouds of gas, set against a dark background filled with stars.
Weird-looking galaxies, with tentacle-like tails or prominent dual streams, appear like jellyfish or bunny ears. But that’s just the start.
A detailed image of the Eta Carinae star system could trick science headlines with its bright, colorful clouds of gas and dust in blue, red, and purple hues swirling around a luminous central region.
Dark matter, dark energy, and the Big Bang are all part of a solid scientific foundation. Here's why popular media often claims otherwise.
A bright, circular object with concentric rings and a surrounding halo set against a dark background, resembling a gap-clearing planet or other astronomical phenomena.
Planets grow from protostellar material in disks, leading to full-grown planetary systems in time. At last, the final gap has been filled.
A wavy line, one meter long, transitions from dark red to bright yellow above a ruler, set against a magenta oval with a blue background featuring drawn human figures.
Until the late 20th century, there wasn't a truly universal standard. Under our current definition, everyone agrees on what "one meter" is.
A field of galaxies in deep space, featuring a bright spiral galaxy at the lower right with a stellar stream escaping the galaxy, and a large, bright red star at the upper left.
Stellar streams are faint trails of stars that appear to "stream" out of galaxies. A new one, escaping galaxy M61, may point to many others.
Three side-by-side images show different views of the Red Spider Nebula in space, captured by JWST, with a bright center and colorful gases in orange, green, and blue against a backdrop of stars.
When dying, Sun-like stars have binary companions, spectacular sights arise from the ionization. JWST spots the Red Spider Nebula in action!
big crunch
There's some, but not overwhelming, evidence that dark energy is evolving. What would it take for a "Big Crunch" to be our cosmic fate?
solar system model
Scientists are notoriously resistant to new ideas. Are they falling prey to groupthink? Or are our current theories just that successful?
An image of El Gordo, a massive galaxy cluster captured by Hubble
The planet, the Solar System, and the galaxy aren't expanding. But the whole Universe is. So where does the dividing line begin?
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.
dark matter
Dark matter has never been directly detected, but the astronomical evidence for its existence is overwhelming. Here's what to know.
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.
star vs planet vs brown dwarf
Red dwarfs are the Universe's most common star type. Their flaring now makes potentially Earth-like worlds uninhabitable, but just you wait.
quasar-galaxy hybrid
Found by Hubble before JWST's launch, GNz7q looked like a mix of a galaxy and a quasar. Was it actually our first known "little red dot"?
Illustration of the universe's large-scale structure with colorful concentric circles, representing cosmic structure distribution, against a black background.
Observations with the Hubble space telescope helped cement dark energy and reveal the Hubble tension. How are these two things so different?
The whole isn't greater than the sum of its parts; that's a flaw in our thinking. Non-reductionism requires magic, not merely science.
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 view of deep space showing numerous galaxies of various shapes and sizes scattered across a dark background.
To learn how our Universe grew up, we have to look at large numbers of galaxies at all distances to find out. Good thing we have JWST!
A colorful, irregular galaxy with bright clusters of stars, some possibly from a generation stars before sun, and nebulae against a dark background scattered with distant stars.
Our Sun only arose after 9.2 billion years of cosmic history: with many stars living and dying first. How many prior generations were there?
Since the time of Galileo, Saturn's rings have remained an unexplained mystery. A new idea may have finally solved the longstanding puzzle.