Universe Expansion

Universe Expansion

A split image shows a star field on the left and a COSMOS-Web survey area diagram on the right, with labeled NIRCam and MIRI footprints alongside the moon for scale, highlighting galaxies explored by JWST science.
The COSMOS-Web has just finalized their release of their full field: larger and deeper than any other JWST program. Here's what's inside.
A large circular particle accelerator laboratory with various machines, cables, and equipment; two people are working near the center on experiments related to the muon g-2 anomaly.
When theory and experiment disagree, it could mean new physics. This time, they solved the muon g-2 puzzle, and saved the Standard Model.
Edwin Hubble and Andromeda galaxy
For decades, astronomers have claimed the Milky Way will merge with Andromeda in ~4 billion years. Here's why, in 2025, that seems unlikely.
A digital 3D visualization shows translucent blue shapes in front of a blue wall and floor, illustrating an abstract concept—perhaps a universe without dark matter.
In our Universe, dark matter outmasses normal matter by a 5-to-1 ratio, shaping the Universe as we know it. What if it simply weren't there?
It rotates on its axis, revolves around the Sun, moves throughout the Milky Way, and gets carried by our galaxy all throughout space.
Close-up of a large, metallic, circular structure with concentric rings and radial lines, illuminated by natural light from one side—evoking experiments that revealed the neutrino mass is smaller than once believed.
The long-elusive neutrino was shown to have a bizarre property no one expected: mass. New, tightest-ever limits have profound implications.
An artist's impression of a cluster of stars.
Many were hoping that JWST would find the first stars of all. Despite many hopeful claims, it hasn't, and probably can't. Here's how we can.
black hole baby universe
Here in our Universe, time passes at a fixed rate for all observers: one second-per-second. Before the Big Bang, things were very different.
heavy neutral atom
If it weren't for the intricate rules of quantum physics, we wouldn't have formed neutral atoms "only" ~380,000 years after the Big Bang.
A colored pixelated grid with rectangular outlines; a legend in the top right labels blue as F115W, green as F200W, and red as F277W—capturing data from the JWST to record a distant galaxy.
Coming from just 280 million years after the Big Bang, or 98% of cosmic history ago, this new, massive galaxy is a puzzle, but not a mirage.
entanglement across space
If all massive objects emit Hawking radiation, not just black holes alone, then everything is unstable, even the Universe. Can that be true?
Two bright, irregularly shaped nebula clouds with blue, purple, and pink gases dominate the dark space background, where dazzling stars twinkle—reminding us that in space, appearances can deceive.
There's an old saying that "what you see is what you get." When it comes to the Universe, however, there's often more to the full story.
Scatter plot with dark blue data points and black dashed elliptical contours centered on the origin, with axes labeled ξ (') horizontally and vertically—similar to plots used by astronomers in studies of the smallest galaxy ever discovered.
With stars, gas, and dark matter, galaxies come in a great array of sizes. This new one, Ursa Major III/UNIONS 1, is the smallest by far.
Astro2020
NASA astrophysics, which gave us Hubble, JWST, and so much more, faces its greatest budget cut in history. All future missions are at risk.
dark energy accelerated expansion
The fact that our Universe's expansion is accelerating implies that dark energy exists. But could it be even weirder than we've imagined?
symmetry
The laws of physics obey certain symmetries and defy others. It's theoretically tempting to add new ones, but reality doesn't agree.
baryon acoustic oscillations
It took nearly 400,000 years, after the Big Bang, to first form neutral atoms. The imprints from that early time can now be seen everywhere.
A dense field of stars and galaxies is visible against a black background, with some bright stars showing lens flares.
The COSMOS-Web survey is now complete, combining JWST and Hubble infrared data. Its spectacular views show us the Universe as never before.
Visualization of a section through the large-scale structure of the universe highlighting cosmic web patterns and distributions.
Since 1998, we've known our Universe isn't just expanding, but the expansion is accelerating. Could the Big Bang itself be the reason why?
A repeating pattern of wireframe 3D geometric shapes intersected by diagonal yellow lines on a black background, evoking a physics break down of forms at the Planck scale.
There are limits to where physics makes meaningful predictions: beyond the Planck length, time, or energy. Here's why we can't go further.
Bright star at the center of a blue nebula radiates mass energy, surrounded by numerous smaller stars, with diffraction spikes visible from the brightest stars.
All stars shine due to an internal source of energy. Usually, it's nuclear fusion: converting mass into energy. What makes them most bright?
Photons come in every wavelength you can imagine. But one particular quantum transition makes light at precisely 21 cm, and it's magical.
According to Stephen Hawking, spontaneously emitted radiation should cause all black holes to decay. But we've never seen it: not even once.
particle physics destroy universe
Empty space itself, the quantum vacuum, could be in either a true, stable state or a false, unstable state. Our fate depends on the answer.
black hole baby universe
Perhaps no existential question looms larger than that of our ultimate cosmic origins. At long last, science has provided the answers.
A vast view of deep space, captured in one of NASA's most important images, displays numerous galaxies of varying shapes and colors against a dark backdrop scattered with distant stars.
The Hubble Space Telescope, launched in 1990, was originally seen as a colossal mistake. This one image, taken in 1995, changed everything.
The spiral galaxy, surrounded by dim stars and interstellar dust, stands out against a dark background, shining brighter than astronomers once imagined.
The most famous Hubble images show glittering stars and galaxies amidst the black backdrop of space. But more was captured than we realized.
Diagram of the universe's expansion with grid patterns and cosmic elements, framed by "Consensus or Crisis?" in white text on black background. This visual encapsulates how cosmology changed from 2000 to 2025, highlighting key theories and discoveries.
25 years ago, our concordance picture of cosmology, also known as ΛCDM, came into focus. 25 years later, are we about to break that model?
A glowing orange planet casts a shadow in space amid a backdrop of stars.
Exoplanets can exist anywhere around their parent stars, even so close that they evaporate or disintegrate. Even the rocky ones.
Two visualizations map the cosmos, displaying color-coded cosmic microwave background radiation. Blue and orange patches indicate temperature variations across a spherical and an oval projection.
It's difficult to project a sphere onto a flat, two-dimensional surface. All maps of the Earth have flaws; the same is true for the cosmos.