Watch the motion of an individual photon using a high-speed camera

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.

Photons do not experience distance or the passage of time

According to special relativity, the speed of light is the cosmic speed limit, and the faster an object moves through space, the less it moves through time. As a result, particles of light only move through space and have no velocity through time, perceiving all locations they travel through simultaneously.

Light appears to slow down as it travels through different materials

As electromagnetic waves interact with particles in a transparent medium, particles vibrate and generate their own electromagnetic waves. The interference of the original and generated waves, which are slightly delayed, results in ensemble light with an effective slower speed but unchanged color.

Photons are both particles of light and messengers of the electromagnetic force

Einstein's model of light as a wave and a massless particle of energy revolutionized physics, and scientists' application of the model led to groundbreaking technologies, including medical imaging and treatments, telecommunication signals, and probes of the quantum and cosmological realms.

Particle accelerators detect subatomic particles using millions of sensors

Calorimeters measure the energy of particles. Tracking devices can measure momentum and charge from the trajectory of particles, which is determined by recording tiny electrical signals. Time-of-flight detectors provide particle velocities directly and particle mass indirectly, giving physicists a suite of properties to compare with those of known matter.

View the electromagnetic spectrum and the properties of different types of light

All forms of electromagnetic radiation, from radio waves to gamma rays, travel at the speed of light in a vacuum, but their wavelengths decrease as their frequencies increase. The light-sensitive nerve cells in the human eye are sensitive to a narrow range of values, which we observe as the spectrum of visible light.

The double-slit experiment is observational evidence for the wave-particle duality

Light and electrons can behave like particles when observed, but they also exhibit wave-like properties in motion, creating patterns through interference. Even larger objects, such as baseballs, have wavelengths, but they are negligibly small compared to their size.

Why it takes tens of thousands of years for light from the sun's core to reach its surface

Photons take about eight minutes to travel through empty space to Earth after leaving the sun's surface. However, traveling from the core to the surface involves these particles of light undergoing a random walk—scattering off charged particles deep in the sun like a pinball—causing a trip that is more than 200 times shorter to last as long as 170,000 years.

Supercollider particles lag behind light by just 10 feet after 14 minutes of travel

The circular shape of the Large Hadron Collider allows particles to be repeatedly accelerated and redirected via electromagnetic fields rather than building equivalent energy in a linear chamber hundreds of miles long. The latter would require 5 trillion D batteries to achieve equivalent near-light speeds.

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.

The speed of electricity may refer to the movement of electrons or energy

In the 18th century, various experiments, including one in which monks holding an iron wire were shocked, suggested that electricity traveled at infinite speed. Advancements in technology, recognizing that electric currents were moving electrons, and the development of the theory of electromagnetism showed that electric signals can travel at near light speed, despite electrons moving much slower.

Watch lightning strike a building at 40,000 frames per second

When the built-up layer of negative charge at the bottom of clouds is sufficiently high, a network of charge filaments will emerge. If one of the filaments meets a rising strand of positively charged particles, a highly conductive path forms, and charges across all filaments move to the path, generating lightning

Explaining pulsars, the cosmic clocks and lighthouses of the universe

As of 2023, over 3,000 of these rapidly rotating neutron stars have been discovered, which contain magnetic fields along which energized particles accelerate and emit light, including X-rays, gamma rays, visible light, and, most commonly, radio waves. The fastest of these, PSR J1748–2446ad, rotates 716 times per second, meaning its surface equator moves at about 24% the speed of light.

Watch insects and animal pollinators in slow motion

Louie Schwartzberg's "Moving Art" series showcases slow-motion footage of oceans, forests, deserts, flowers, and more. In this excerpt, organisms such as bats, monarch butterflies, bees, and hummingbirds are shown interacting with one another and with flowering plants.

Scientists keep track of time via light absorbed by cesium and strontium atoms

These absorptions happen in cycles, where one second is defined as 9,192,631,770 cycles of cesium atom radiation. Strontium atoms can be used to make clocks that do not gain or lose a second in 15 billion years.

Synchrotron radiation has revealed the fur color of creatures millions of years old

When electrons are accelerated in the loop, they produce intense X-rays that can reveal properties of a sample struck by them, just as X-rays can be used to show bone structure in humans. Studying the reflected light from fossils can uncover the presence of known pigmentation compounds.

Watch a crystal undergo X-ray diffraction to determine its internal geometry

In the early days of X-ray crystallography, getting photos of a single sample could take dozens of hours, followed by months of mathematical analysis. Today, automation and computer software can complete such tasks in a few hours.

Quantum physics explained in 22 minutes

Brian Cox, Royal Society Professor for Public Engagement in Science, discusses the fundamental principles of quantum mechanics, emphasizing their importance in understanding the nature of reality and their practical applications in emerging technologies like quantum computers.

Over 120 cameras are used to film a single F1 race

Watching a Formula 1 race today is an immersive experience: Every car has onboard cameras; there are helicopter, drone, and lift shots; nearly every corner has a camera to document drivers jockeying for position; and over 120 cameras are used to film a single race.

Statcast runs machine learning models in the 23-second gap between every pitch

The same Hawk-Eye cameras that track spin rate, exit velocity, and sprint speed also feed proprietary team models that update in near-real time. Some organizations have built streaming pipelines to surface insights mid-at-bat before the next pitch arrives.

The selfie camera exists thanks to Einstein's discovery of the photoelectric effect

Smartphone cameras utilize sensors such as CMOS or CCD to capture light by converting it into electrical signals through the photoelectric effect. Einstein explained this effect by demonstrating that light behaves as both particles and waves simultaneously, a discovery that earned him the Nobel Prize in physics.

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.

Fly through the deepest image of space ever taken by the Hubble Space Telescope

Taken over 11 days between 2003 and 2004, when the space telescope was aimed at a seemingly empty patch of the sky, the Hubble Ultra-Deep Field revealed about 10,000 sources of light, most of which are entire galaxies. This visualization expands the 2D image into a 3D view spanning 12 billion years.

Physicists detect the sound of heat in superfluids, theorized since 1938

Referred to as "second sound," the flow of heat in a superfluid resembles a sound wave bouncing back and forth. The heat-mapping techniques used to make the detection may improve the study of neutron stars and superconductors.

Watch a video that visualizes what really happens inside a credit card network when you make a purchase.

Every tap sets off a lightning-fast relay. When someone buys coffee with their Visa, a tiny "runner" races between the coffee shop's bank, Visa's network, and their bank—all in under a second. The catch? No money has actually moved yet. Here's what really happens behind that instant "Approved."

Explore a guide to observing comets

Binoculars or telescopes can be used to see vivid tails, glowing comas, and brief bursts of brightness from these celestial objects. For photography, a DSLR or mirrorless camera with a wide-aperture lens, long exposure settings, and accessories such as tripods and star trackers is recommended.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

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

The first image of a black hole was captured by creating an Earth-sized virtual observatory from a network of eight radio telescopes.

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.

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

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

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.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

Explore chaos in this simulation of two double pendulums, where small differences in the release angles produce wildly different outcomes.

When caught in the mouths of cardinal fish, seed shrimp release glowing, bioluminescent chemicals, which alert predators of the cardinal fish, prompting the shrimp's ejection.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by more than 1.5 million Muslims each year.

The first horror movie is believed to be George Méliès' 1986 short 'The Haunted Castle,' which pioneered the use of special effects

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

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

Long before Major League Baseball began allowing instant replay for balls and strikes, an umpire reluctantly used the technology to determine whether a hit was a home run, a move that inadvertently ushered in a new era for the sport.

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.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

The most expensive ad of all time was for Chanel No. 5 perfume and cost roughly $33M to produce in 2004—about $57M in today's dollars.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

Hedge funds, the private investment firms that trade a wide swath of financial assets, make money by imposing steep fees on investors and from the fund's investment performance.

Watch contemporary footage covering the US-backed Shah of Iran fleeing the country in the face of the 1979 Iranian Revolution

About 12.5% of US adults experience a phobia in their lifetime, a diagnosis that hinges on the intense fear interfering with daily life and persisting for at least six months.