Explore Albert Einstein's Zürich notebook and review his notes on relativity

To develop general relativity, Einstein relied on his college friend, Marcel Grossman

Recognizing the mathematical complexities of generalizing special relativity with a new picture of gravity and acceleration, Albert Einstein had Grossman introduce him to tensor calculus. Years before developing the precursor to GR together, Einstein would use Grossman's lecture notes to prepare for his exams.

Mathematician David Hilbert developed general relativity equations before Einstein

Although working independently of one another, the two exchanged correspondence in the lead up to November 1915, when Hilbert submitted their gravitational field equations five days before Einstein presented their work. An error in Hilbert's formulation and its nonpublication until March 1916 would leave credit for general relativity to Einstein.

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...

How a solar eclipse proved Einstein's theory of gravity

For hundreds of years, Isaac Newton's laws of gravity and motion accurately predicted every observation and measurement involving orbits. With the advance of technology, more precise measurements revealed anomalies, including the orbit of Mercury, which Albert Einstein's general theory of relativity could explain. This article details the two frameworks and how they went head-to-head during an eclipse for gravitational supremacy.

Explore a simplified breakdown of the Einstein field equations

Often depicted as one formula, Einstein's equation represents a suite of 16 nonlinear partial differential equations, which can be simplified to six unique ones, that relate the geometry of spacetime to the presence of mass and energy.

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).

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.

During his 'miraculous year,' Einstein published four groundbreaking papers

The 1905 "annus mirabilis" papers explained the photoelectric effect, Brownian motion, the absolutism of the speed of light, and mass-energy equivalence, revolutionizing scientists' understandings of space, time, mass, and energy. For the discovery of the photoelectric effect, Einstein won the 1921 Nobel Prize in Physics.

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.

One of Einstein's papers challenged quantum theory but helped confirm entanglement

In 1935, Einstein suggested that quantum mechanics was incomplete due to its strange implications about entangled particles. Their challenge led to decades of experiments that eventually proved distant particles could affect each other instantly.

Albert Einstein taught courses in Davos

This silent video from the 1920s shows footage of Einstein at Davos. The famous scientist spent time there, delivering public lectures on his theory of relativity as part of the town’s university courses.

Understanding how gravity works at the quantum scale is physics's greatest challenge

While the theory of general relativity explains how gravity works and quantum mechanics explains interactions at the subatomic scale, the two frameworks contradict one another. Developing a model of gravity mediated by particles can help complete the Standard Model.

Searching for Albert Einstein's stolen brain

Within moments of Einstein's 1955 death, someone reportedly ferreted away the 76-year-old genius's brain. Decades later, a reporter's editor told them to solve the case. This 64-minute podcast episode follows the work of Steven Levy, the reporter who ultimately tracked down Einstein's brain, which had been sliced and stored in slides, goo, and a cardboard box in a scientist's office.

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.

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.

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.

The ideas of Einstein and Freud combined in 'The Persistence of Memory'

The Persistence of Memory was painted on a canvas roughly the size of a sheet of paper, depicting a desolate landscape with melting clocks, ants, and a distorted figure. The piece incorporates Freud and Einstein's ideas, resulting in a haunting composition symbolizing time's fluidity and Dalí's personal anxieties.

Fritz Zwicky predicted the existence of dark matter and neutron stars

The former resulted from analyzing the motion of galaxies in the Coma Cluster, a subset of the approximately 30,000 galaxies he cataloged during his life. When hypothesizing an origin for observed high-energy particles called cosmic rays, Zwicky and colleague Walter Baade thought they could come from exploding stars, or supernovae—a term he coined—which would leave behind a collapsed star made entirely of neutrons.

How entanglement lies at the heart of quantum computing

Theoretical physicist and mathematician Frank Wilczek boils down the complex notion of quantum entanglement into this reasonably understandable summary. Wilczek discusses the concepts of quantum entanglement and how it relates to other ideas like the Many-Worlds Interpretation (MWI) of quantum mechanics. What sounds a bit "science-fictiony" can have actual real-world and concrete applications.

Listen to the audiobook version of 'A Brief History of Time'

First published in 1988, Stephen Hawking's most famous novel has sold more than 25 million copies in 40 languages. Through non-technical terminology, Hawking discusses the nature of space and time, general relativity, quantum mechanics, gravity, black holes, and cosmology.

How a competition honoring a king's birthday uncovered history's first chaotic system

A committee established a contest for King Oscar II's 60th birthday, featuring four unsolved problems in mathematics, including one on proving the stability of a system of more than two objects held together by gravity. Focusing on three celestial objects, Henri Poincaré won the prize for his proof, which he later learned was incorrect and, upon correcting it, instead proved these systems to be unstable.

The life of Edward Lorenz, who originally used a seagull in his 'butterfly effect' metaphor

By accidentally finding that rounding one variable to its third decimal place and re-running a weather simulation produced a drastically different two-month forecast, the American mathematician established the field of chaos theory. His paper—"Predictability: Does the Flap of a Butterfly's Wings in Brazil Set off a Tornado in Texas?"—introduced the well-known metaphor for the behavior of chaotic systems. (Some readers may experience a paywall.)

The history of the 10 axioms of Zermelo–Fraenkel set theory with choice, regarded as the most universal foundations of math

Like postulates in geometry—accepted truths that form the logical building blocks for formal proofs of more complex theorems—axioms cannot be proven, but set the underlying logic and rules for systems. The ZFC axioms resulted from painstaking work to identify the underlying rules of mathematics and are built on the premise of sets, or well-defined collections of elements.

'Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world.'

- Albert Einstein

An existentialist reading list

If you’re looking for a starting point for diving into existentialist thought, this is a great resource. Its titles are not exactly obscure—Albert Camus’ “The Stranger,” Franz Kafka’s “The Trial,” and Søren Kierkegaard’s “Either/Or” are among the most famous works in Western literature—but the list provides some digestible context for each text, which will help you decide the best place to begin your journey.

Explore over 46,000 pages of Charles Darwin's manuscripts

The American Museum of Natural History hosts almost 35,000 digitized folios related to evolution within the fields of botany and zoology from Darwin's Beagle voyage. High-resolution color images, geological findings, and annotated books from Darwin's personal library are also viewable.

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.

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.

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.

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

The term 'algorithm' originated from the Latinized name of al-Khwārizmī, a 9th-century mathematician whose works introduced Arabic numerals and the decimal-based numeral system to Europe and whose treatise 'Al-Jabr' gave algebra its name.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Before writing 'Walden,' transcendentalist Henry David Thoreau nearly burned down his hometown with a campfire that grew out of control.

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

Learn more about the history of fireworks, which dates back to an accidental invention during an alchemist's quest for information about immortality.

American dance legend Martha Graham, sometimes called 'the Picasso of dance,' refused to perform at the 1936 Olympics in Berlin and conceived the piece 'Chronicle' in response to the experience.

Warren Buffett's former professor Benjamin Graham is known as the 'father of value investing,' a strategy in which investors seek to buy stocks trading below their intrinsic worth.

The idea for the Federal Reserve was conceived in secret in 1910—with bankers donning duck hunt gear for disguise while traveling to a remote country club on Georgia's Jekyll Island

Famed poet TS Eliot rejected the manuscript for George Orwell's political fable 'Animal Farm,' writing that its criticism of authoritarianism was not 'the right point of view.'

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.

The Brothers Grimm were lawyers before they were storytellers, and became interested in fairy tales as they began investigating how rules and customs had been passed down through cultures.

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.

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.

Use this calculator to find the dollar value of your mental load, from meal planning to coordinating after-school care for your children.

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

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

How the most famous Ebola book, The Hot Zone, which sold 3.5 million copies and was translated into 30 languages, got aspects of the disease so wrong.

20,000 letters to the advice columnist 'Dear Abby' provide insight into prevailing sex, religion, and LGBTQ fears, anxieties, and concerns from the 1950s onward.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time