Astronomical models suggest dark matter must be 'cold,' or slow-moving

Dark matter's invisible pull shapes galaxies and our understanding of the cosmos

Though it makes up about 25% of the universe, dark matter can't be seen directly; its existence is inferred through its gravitational effects, like the unexpectedly fast rotation of galaxies. The concept began in 1933 but gained wide acceptance after Vera Rubin's galaxy rotation studies in the 1970s.

As of 2025, the best cosmological model of the universe includes dark energy

The Lambda cold dark matter model uses the Greek letter to denote the presence of a cosmological constant version of dark energy, alongside slow-moving dark matter and ordinary visible matter. It can account for the observed distribution of galaxies, the structure of the cosmic microwave background, the acceleration of the universe, and the abundance of hydrogen.

Dark matter may be one of many hidden particles that don't interact with light

Theoretical candidates, such as axions and supersymmetric WIMPs, may open the door to a new branch of particle physics that shapes the cosmos through gravity. Some of these particles may constantly pass through us but interact too weakly to be detected.

Dark matter's limited force interactions make its detection difficult

Despite making up the vast majority of matter in the universe, dark matter can only be directed indirectly via its influence on other objects through gravity, the weakest of the fundamental forces. This means direct detection of dark matter may only be possible with future, more sensitive instruments.

View a simulation of the dark matter filaments that make up the cosmic web

The distribution of matter in the universe is not uniform, with interconnected threads of galaxy clusters surrounded by voids of empty space. Simulations of the universe show this is only possible within 13.8 billion years—the universe's age—if a foundational network of seeds—dark matter halos—were present to gravitationally attract visible matter.

Dark matter and dark energy, explained

What is dark energy? What is dark matter? Well, if we knew exactly, we would have a Nobel prize—we know that they exist, though. Scientists have theorized that the former may be a property of three-dimensional space itself, while the latter could be exotic particles that interact with almost nothing. This video from Kurzgesagt explains what we know and what we don't.

One study suggests that dark matter may have originated from a dark Big Bang

A student-faculty team at Colgate University modeled the event as occurring months after the conventional Big Bang and determined the potential gravitational wave signal that would have been left behind. Future gravitational wave detectors are expected to be sensitive enough to observe this signal, if it exists.

The structure of the Bullet Cluster cannot be explained without dark matter

In gravitational lensing, mass bends spacetime, deflecting passing light rays. Instead of this deflection being strongest near the gas within galaxies, where visible matter is densest, lensing is strongest in front of the collided galaxies. This suggests the presence of clumps of dark matter that were not slowed by friction during impact.

New model replaces the Milky Way's central black hole with dark matter

A study published in Monthly Notices of the Royal Astronomical Society states that a dense core of fermionic dark matter, rather than a supermassive black hole, could explain both the rapid orbits of stars near the Milky Way's center and the galaxy's large-scale rotation detected in Gaia mission data.

Simulate the distribution of dark matter within a galaxy

By modifying the dark matter density at different distances from the center of a simulated galaxy, you can plot the resulting orbital speed of stars. Preset data enables you to replicate astrophysicists' work in determining the dark matter concentration that best fits observed structures.

Dark stars are hypothetical stars that would have existed in the early universe

Primarily composed of visible matter, this celestial object would also contain a significant amount of dark matter that would annihilate with itself, converting its mass into energy. This energy would prevent the star from collapsing under its own gravity and from triggering nuclear fusion until its dark matter fuel was exhausted.

Axions, a hypothetical subatomic particle, are a leading dark matter candidate

Among the possibilities for what makes up dark matter, some physicists champion axions, which could clump into galaxy-scale quantum states. These states would act as massive, unified superparticles that could explain the observational evidence for the universe's missing matter.

The European Space Agency's Euclid telescope maps dark matter

As light rays travel near massive objects in space, their paths can be distorted on their way to Earth, causing objects to appear displaced, magnified, shrunken, or sheared. By simulating these effects for various mass distributions, astronomers can match the distortion to a simulated mass and compare it with the observed visible matter to infer the presence of dark matter.

Dark energy causes 97% of the galaxies to move faster than light

Although special relativity prevents objects from moving faster than the speed of light, the expansion of the universe, which increases with distance between objects, produces observed superluminal motion. This does not violate the theory because galaxies are moving with the expanding space, rather than through it.

The Standard Model predicts massless particles we have observed to have mass

Neutrinos—elusive cousins of the electron that rarely interact with other matter—have been observed to transform into one another, which can only occur if they have mass. The theory also cannot explain why the universe has much more antimatter than normal matter.

A cup of coffee on Earth contains about 100 proton masses worth of dark matter

The estimate is based on Earth's location within the Milky Way and the dark matter cloud it resides in. Because scientists do not know the nature of dark matter, the mass may be accounted for with any number of dark matter particles of varying mass.

Mars' orbit may provide evidence that dark matter is made of primordial black holes

Physicists at MIT have found that, statistically, one such microscopic black hole should pass through the solar system every decade, which they predict would introduce a detectable wobble in Mars' orbit. Such black holes would have formed in the early universe from collapsing gas clouds and scattered as the universe expanded.

Our solar system is currently traveling through a 'dark matter hurricane'

The phenomenon refers to a stream of cosmic debris, including stars and dark matter, leftover from a small galaxy that passed too close to the Milky Way and was torn apart. There are over 30 such streams known in our galaxy, and the stream intersecting the solar system is predicted to continue to do so for millions of years.

Dark comets appear to be rocky asteroids but move like comets

Cometary orbits are known to exhibit accelerations independent of gravity that result from forces related to the release of gases. Dark comets exhibit this behavior but lack visible clouds of frozen material that have turned into a gas—the coma the comets display—indicating minor quantities of escaping subsurface ice.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

The hypothetical particle that travels faster than light

Astrophysicists inspired by science fiction developed the theory of the tachyon—a Greek word for "fast"—which is a field or particle hypothetically able to travel faster than light. Although no experiments have confirmed any part of it, it's a fun theory to consider.

Delays in the decay of unstable particles provide evidence for time dilation

Physicists used the muon half-life measured in labs to predict how many should reach detectors on Earth's surface after their production in collisions between atmospheric molecules and cosmic rays. Higher detection rates were consistent with a longer half-life due to slower movement through time.

Light can be used to slow the motion of atoms

While photons possess energy, they also have momentum, which allows them to collide with other particles, much like billiard balls, thereby slowing them down and reducing their kinetic energy, or temperature. Using multiple lasers from different directions, particles can be cooled to within one degree of absolute zero.

The scattering of light in the early universe prevents seeing the beginning of time

A "cosmic fog" of elementary particles in the early universe prevented light from traveling far before being absorbed. Only 380,000 years after the big bang, when the first atoms formed, was light free to travel and reach telescopes for study.

Astronomers use a star's color to determine how fast it's moving

According to the Doppler Effect, light from objects moving away from Earth shifts toward the red end of the electromagnetic spectrum, with the severity of the shift correlating to recession speed. Due to the universe's expansion, light from the most distant galaxies can be moved from ultraviolet to infrared.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

Heat slowly moves through Earth's mantle like softened wax

Energy trapped during Earth's formation and released via the radioactivity of elements is carried by convection currents towards the surface, while cooler, denser material sinks. The planet's core is almost as hot as the sun's surface.

Neutron stars, the remains of some massive stars after they explode in a supernova, are the densest directly observable objects in the universe.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

The deadliest aspect of volcanic eruptions is often not lava, but pyroclastic flows—avalanches of ash, gas, and rock that can move more than half the speed of sound.

Track the location of the Voyager probes, currently between 13 and 15 billion miles away from Earth.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

Electrical grids worldwide must double their power delivery capacity by 2050 to meet surging demand from AI and electric vehicles.

Browse a detailed visual analysis of over 200,000 similes—comparisons that often use 'like' or 'as'—from popular fiction to see how frequently writers the same idiomatic expressions.

Frank Lloyd Wright's houses are historically hard to sell because they're old, subject to local landmark commissions, and often unfashionable

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight

In 1945, Surrealist artist Salvador Dalí and legendary animator Walt Disney began collaborating on a short film that was not completed until 2003, years after both men had died.

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

Stanford built a Google Maps for the Roman Empire, revealing how much it cost to travel in the ancient world