Experimenting with space-time

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...

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.

Einstein and the fourth dimension

How Einstein's greatest theoretical achievement contains a simple but mind-bending proposition—the dimension of time is physically connected to the three observable spatial dimensions.

How neutron stars serve as laboratories for testing Einstein's theory of gravity

Data from a 16-year study of an orbiting pair of spinning neutron stars showed that measurements of gravitational wave energy and the bending of light around the system were consistent with predictions made by general relativity to an accuracy of at least 99.99% across seven tests. (Some readers may experience a paywall.)

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.

Massive objects can significantly bend light to produce gravitational lensing

The theory of general relativity posits that mass and energy bend space and slow down the passage of time. One consequence is that massive objects, such as black holes, curve spacetime to such an extent that light from background sources can loop around them, producing multiple images or ring-like patterns.

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.

Explore our favorite visualization of the immense scale of space, from an astronaut to the size of the observable universe

Explore the scale of the universe in this interactive adventure

The sheer enormity of the universe escapes our ability to conceive of its scale, despite the best efforts of human imagination. This interactive provides an intuitive sense of how small we are, from a single astronaut to the Milky Way and beyond.

Visualize chaos with the orbit of three or more objects bound by gravity

In this simulation, users can simulate randomized and preset orbital configurations for up to 10 celestial bodies to observe the system's evolution in an interactive 3D space. The same configurations can produce different orbital behavior—a feature of chaos—by making small changes to an object's mass under advanced settings.

The mathematics of general relativity does not rule out the existence of wormholes

Such objects, also known as Einstein-Rosen bridges, would resemble funnel-like tunnels connecting two regions of spacetime, allowing for instant travel across the universe. However, such structures would be incredibly unstable and require undiscovered materials with negative energy to keep them open.

What is space-time?

Space-time is a complex subject, but this Livescience article makes an effort to disentangle the topic. Somewhat akin to a sheet of rubber that can be warped and bent in parts, space-time is a bit more involved that that. However, the analogy makes this and other aspects of the concept simpler to grasp.

Gravity Probe B verified that rotating objects drag spacetime

The experiment involved attaching four freely floating gyroscopes to a telescope aimed at a distant star for a year. The observed angular shift of the gyroscopes as a result of Earth's rotation pulling on spacetime was approximately 0.0000012 degrees from the amount predicted by general relativity.

Creating 'Interstellar's' black hole blended visual effects with real physics models

Theoretical cosmologist Kip Thorne was consulted and collaborated with the film's visual effects team to develop new rendering software, integrate general relativity, and generate ultra-high-resolution visuals. The results were so accurate, they were published in scientific journals.

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.

Explore an interactive map of the unified theories of everything

This interactive concisely describes many highly complex theories ranging from quantum gravity and black holes to dark matter and energy. Supplementary resources, key questions, and possible solutions accompany each description. As of 2026, no developed theory provides an accepted explanation of all observed phenomena in the universe at all scales.

Einstein created a mathematical term for anti-gravity to keep the universe static

General relativity predicted that the gravity of all the matter in the universe would cause it to collapse, contradicting the belief at the time that the universe was constant and unchanging. Albert Einstein added the cosmological constant to his equations, which acted like anti-gravity, to "fix" his math.

Understanding how and when time began requires a theory of quantum gravity

Rewinding the universe to the big bang compresses all matter, energy, space, and time into a single point, necessitating a model that combines general relativity with quantum mechanics. Although physicists understand time to have begun when the universe did, a clear understanding of the mechanisms involved remains unclear.

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

In "Velocity Raptor," space and time warp as you make your way across a room of obstacles at "normal" speeds. Take advantage of these relativistic effects to solve puzzles involving clocks running at different rates and colors shifting as a result of your movement.

How the moon moves, an interactive lesson

How exactly does the moon move, and why does it move that way? In this ridiculously comprehensive interactive explainer, you can conduct experiments to see how the moon rotates and as it moves around the Earth, while learning how gravity works by controlling the path and speed of different objects. Dive into this beautiful, simple explainer to learn the basics on gravity and the moon.

Simulate the impact of an antimatter bomb around the world

Using "Total Annihilator," users can click on a location on the map, select the antimatter mass, and the observation altitude before detonating the bomb. Scrolling through the left sidebar reveals the impacts of the detonation, including the sizes of the resulting fireball and thermal pulse, the spread of ionizing radiation, and the atmospheric effects.

The origins of our fascination with time travel

Humans have been captivated by the prospect of leaping forward and backward in time for thousands of years. Georgia Institute of Technology Science Fiction Studies Professor Lisa Yaszek recounts how the concept has been utilized by storytellers from 400 BCE to modern-day to explore our relationship with the supernatural, technology, and the past. In a way, this historical recounting is a journey through time.

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.

Explore the Earth at night from space

See the planet in all its luminosity with this NightEarth app, an interactive spherical globe showing real satellite imagery of Earth. Toggle between views of real-time clouds, aurora borealis activity, and more.

See a timeline of the space race

This interactive timeline chronicles the space race from its Cold War origins to the moon landing, highlighting key figures, pivotal moments, and rapid technological advancements. It combines archival photos, video, and links to related material.

The weather time machine

A fun interactive on how old ships’ logs are giving scientists new insights into the past and future of the Earth’s changing climate (w/maps and pictures).

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

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

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.

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

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.

Against his wishes, Albert Einstein's brain was removed before his cremation, and the pathologist responsible stored it for decades in mason jars within a beer cooler.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

Explore the known asteroids, comets, and spacecraft involved in asteroid studies within our solar system with 'Eyes on Asteroids,' a 3D visualization from NASA.

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

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.

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

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

This site reaches millions of visitors who are tired of AI chatbots and seeking human connection. Pretend to be an AI chatbot and ask questions, provide answers, and draw for people in real time.

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

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.

See the most iconic photos from four decades of LIFE magazine

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

Use this tool to calculate the dollar value of your parental mental load, from meal planning to coordinating after-school care, then see resources that help generate solutions.

English mathematician Ada Lovelace wrote the first computer algorithm a century before computers existed and hypothesized that computing devices would one day be able to compose music—foreseeing the generative AI systems of today.

Apeirophobia is an overwhelming fear of living forever, perhaps stemming from the brain's inability to conceptualize an infinite life.

Netflix profits when you're not watching, and its movies are designed that way—read a detail-rich critical essay exposing lesser-known Netflix takes

Legendary architect Frank Lloyd Wright designed the SC Johnson headquarters in Wisconsin, aiming to make a cathedral-like workplace

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'