Play a puzzle game where the speed of light is reduced to everyday speeds

Play an incremental game that teaches the history of particle physics

Developed during the CERN Summer Student Webfest 2014, this game tasks you with building the reputation of your particle accelerator as you discover particles and hire staff to collect data. A historical breakdown accompanies each discovery, allowing you to recreate the timeline of the field.

Experimenting with space-time

Einstein's theory of general relativity—that mass literally bends space and time—can be difficult for the human brain to imagine. This interactive resource lets you create celestial objects, imagine their effect on space-time, and see how they interact with each other (best viewed on desktop).

Photons do not experience distance or the passage of time.

Chess can be played at lightning-fast or classical speeds

Time controls shape how the game is played—from bullet matches under three minutes, to blitz games under 10, to classical contests lasting over an hour. Each format demands different skills, from rapid intuition to deep calculation.

Special relativity shows how motion at high speeds reshapes time, space, and energy

Einstein’s 1905 special theory of relativity revealed that the speed of light is absolute in the universe, forcing time and space to vary with one's speed. This idea led to the famous equation E=mc2, which shows that mass and energy are interchangeable.

According to the special theory of relativity, the faster objects move through space, the less they move through time, and therefore age more slowly.

Explore an optical table to create quantum physics experiments

This interactive teaches users to create quantum experiments through lessons resembling video game levels. Users can also use the virtual lab to visualize landmark quantum experiments like entanglement, teleportation, cryptography, and quantum computing, or create their own experiments with drag-and-drop elements.

Visualizing Einstein's special relativity

Before Einstein developed his theory of general relativity, he worked out what is known as special relativity—or why time is experienced different for different observers. The breakthrough rests on his theory that light travels at a constant...

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.

During a 2013 speed run of 'Super Mario 64,' the protagonist was inexplicably warped up to a new location—a glitch that would later be attributed to a cosmic ray flipping a bit within a byte responsible for tracking Mario's height.

Play a game of 1440's Tetris.

Discoveries in electromagnetism, which suggested that light traveled at a single speed, became the catalyst for overturning Isaac Newton's view that all speeds are relative and could appear to change based on one's perspective.

Einstein’s theory of special relativity

Special relativity, formulated by Einstein, describes how space and time are linked for objects moving at constant speeds. It states that the speed of light is constant for all observers, leading to time dilation (moving clocks run slower), length contraction (moving objects shrink), and mass-energy equivalence (E = mc²). This video breaks down how motion and time are fundamentally related.

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.

Play a space junk collection game

Developed by Astroscale, a company with a contract from the UK to remove satellites from orbit safely, the game enables players to simulate the company's planned COSMIC mission and test their space debris-catching skills.

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.

Understanding time dilation

The faster you go, the slower time ticks for you. And the stronger the gravitational field acting on you, the slower time ticks for you. These phenomena – collectively called time dilation – were first explained by Albert Einstein’s theories of general and special relativity. In this 11-minute video, beloved astrophysicist Neil deGrasse Tyson explains them to comedian Chuck Nice.

Tachyons are theoretical particles that travel through space faster than light

The equations of special relativity require these objects to possess imaginary mass, and they would travel faster the more energy is taken away from them. The existence of tachyons would necessitate an unknown form of matter and lead to paradoxes involving information that can hypothetically travel backward in time.

Play an interactive game to explore and learn about Hubble images

Aboard the fictional USS Hubble, users can choose their own adventure to investigate the solar system, our galaxy, and the universe beyond. Each option directs users to a real image accompanied by relevant information and additional media elements, such as a time-lapse of the moon Phobos orbiting Mars.

According to the equivalence principle, objects in a closed space cannot tell the difference between whether they are accelerating or experiencing a uniform gravitational field.

The finite speed of light means we can only perceive the world's past

When objects emit or reflect light, it takes time for the light to reach an observer and be detected. During the travel time, the object may have changed, limiting detections to describing the conditions of the object when the light was first emitted or reflected, before it was detected.

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.

According to the special theory of relativity, because the passage of time depends on how quickly objects move through space, people will not agree on the order of events they observe if they are moving at different speeds.

The underlying fabric of the universe—spacetime—changes shape in the presence of mass and energy, which affects measurements of space and time.

Time disappears when encompassing all quantum configurations across the universe

The Wheeler-DeWitt equation, a modified version of the Schödinger equation—the formula that describes the evolution of the quantum configuration of a system—describes the quantum state of space-time across the universe. The transformation causes the variable of time to disappear, suggesting it is not a fundamental, physical parameter of the cosmos.

By analyzing the color of starlight, astronomers can determine how fast stars within a galaxy are moving toward or away from Earth, revealing the expansion rate of the universe.

Five potential ways to achieve time travel

While the author discounts the possibility of traveling to the past, it lays out five hypothetical modes of catapulting into the future: speed, gravity, suspended animation, wormholes, and light. Each has some scientific basis, but none are realistic for humans. Read the article to learn where they offer promise and where they fall short.

Explore a visualization of curved spacetime under general relativity

While depictions involving bends in elastic fabrics are common to illustrate gravity, they are circular representations that rely on gravity in the real world to depict gravity in the model. The river model instead shows how bends in spacetime convert speed through time into speed through space, producing acceleration.

Meta's Quest and other mixed reality devices can make learning new skills easier

PianoVision utilizes the passthrough visibility of a headset to illuminate which keys to play on a real piano or keyboard, providing an immersive, software-based learning alternative to human instruction. Similar apps also offer virtual model replacements for physical devices, such as a virtual piano, to practice with.

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

Although light travels over 3 million football fields per second, cameras that capture trillions of frames per second can observe individual particles of light as they interact with atoms in materials they travel through. Such observations can be used to determine the speed of light in different materials.

In comic books, cosmic rays have been described as capable of accelerating evolution, granting humans superpowers, restoring health and energy, and powering advanced technology.

The Wiki Game: get to one Wikipedia topic to another as fast as you can

Wikipedia, the free, community-built encyclopedia, uses hyperlinks so users can explore topics within topics. This tool often leads readers to go down endless rabbit holes, from one topic to another, endlessly. Now, you can make a game of it by...

Particles produced in cosmic ray showers that would normally decay long before they reach Earth's surface are observed in ground-based detectors because they experience time more slowly when moving near the speed of light—a phenomenon predicted by special relativity.

Time seems to stop for objects at the event horizon of black holes

At that location, the warping of space-time is so severe that the entirety of an object's space-time motion is solely through space, leaving it immobile in the time dimension. Faraway observers looking at the object would see it appear frozen before slowly dimming and reddening.

Quantum mechanics and general relativity—two of the most successful explanations of the physics seen across the universe—are logically incompatible with one another because they use contradictory models for space and time.

At the Large Hadron Collider, protons are accelerated so close to the speed of light that they would lag behind a laser by just 10 feet after 14 minutes of travel.

Lasers can be used to reduce the motion of atoms because particles of light—photons—can collide with particles of matter, as billiard balls do, to slow them down.

Orbital spaceflight requires reaching 23 times the speed of sound

After the spacecraft accelerates up to at least 17,500 miles per hour, space tourists can travel in elliptical orbits hundreds of miles above Earth for days or weeks at a time. Suborbital flights instead max out at about 2,200 miles per hour and travel only 50 to 70 miles above Earth's surface for a few minutes.

The wave nature of matter can produce phenomena like negative time and retrocausality

Within quantum mechanics, matter simultaneously exists as both fixed particles and extended waves, allowing it to emerge across barriers—just as sound travels through walls—before it fully enters the obstacle. The resulting measurements can show that particles spent negative time within a barrier, with the future occurring before the past.

Space probes propelled by lasers may one day visit distant planetary systems

Launched in 2016, Breakthrough Starshot is a project to send gram-sized spacecraft to the nearest stars and their planets at 10% to 20% the speed of light after being accelerated by ground-based laser systems. The project requires orders of magnitude advancements to current technology.

Relative motion between a source and an observer shifts the color of observed light

The phenomenon, known as the Doppler effect, is the result of experiencing an increase in the frequency of observed waves when approaching a source and a decrease when moving away. Because this property corresponds to color, approaching objects appear bluer than normal—blueshift—and receding objects appear redder than usual—redshift.

Watch a visualization of what it would look like to move along Earth's surface as fast as the International Space Station, or about 23 times the speed of sound.

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

Observations of colliding neutron stars by the Laser Interferometer Gravitational-Wave Observatory in 2017 confirmed that gravity travels at the speed of light.

Watch a YouTuber solve a Rubik's Cube while in free fall

He broke a world record, completing the task in the sky in just 23.333 seconds.

A virtual art gallery in the mode of 'Doom'

One of the earliest video games to use 3D interfaces, 1993's "Doom" was a first-person shooter set on the moons of Mars which ended in hell. It became one of the most critically and commercially successful games of all time. Now, you can wander virtually in an art gallery in the mode of the game, sipping wine and perusing pixelated versions of classic works of art.

The extreme precision of atomic clocks highlights gravitational time dilation

Scientists at the National Institute of Standards and Technology have constructed clocks made out of stacked strontium atoms, which show differences in the passage of time across just a millimeter of height consistent with predictions from general relativity, where atoms closer to Earth's center tick off time more slowly.

The speed of electricity may refer to the movement of electrons, which is on the order of a fraction of a millimeter per second, or energy, which is near the speed of light.

A nuclear reactor's characteristic blue light is produced from superluminal particles

When light travels through water, its effective speed is 25% lower than its speed in a vacuum. Just as sound waves bunch up and produce a sonic boom when objects move faster than the speed of sound, particles moving faster than this reduced speed generate a shock wave of light, visible as a blue hue.

A scientific analysis of famous time travel stories

This 8-minute video explores how time travel influences the narrative arc of several movies, books and video games, from Harry Potter to A Christmas Carol. (Warning: it contains spoilers!) J.K. Rowling and Charles Dickens set myriad parameters as they’re worldbuilding to avoid paradoxes and create quasi-logical timelines. By drawing diagrams as he’s speaking, the video breaks down how time works in some of popular culture’s most beloved fictional universes.