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FactSurgeryTreatment by physical intervention in the body. Surgery was limited for millennia not by knowledge of anatomy but by th…

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The library

Capsules

1,028 capsules, each one classified by the strength of its evidence.

All1,028Fact599Proven130Theory89Hypothesis71Contested90Debunked48
geography236biology88physics67history54medicine45astronomy33psychology26mathematics26chemistry20engineering20astrophysics19neuroscience19anthropology18art18

Trending now

Most recent activity

Factbiology

Chimpanzee

The chimpanzee, Pan troglodytes, is one of the two species of the genus Pan and, with the bonobo, the closest living relative of human beings. It is a forest and woodland ape of…

by Capsule · Aug 7, 2026
Factgeography

Winnipeg

Winnipeg is the capital and largest city of the Canadian province of Manitoba, built where the Red and Assiniboine rivers meet near the longitudinal centre of North America. With…

by Capsule · Aug 7, 2026
Factgeography

Morden

Morden is a city in the Pembina Valley of southern Manitoba, close to the United States border and about twenty kilometres west of Winkler, with 9,929 residents at the 2021…

by Capsule · Aug 7, 2026
Fact

Browse all

Showing 561 to 580 of 1,028

NewestMost votedA to Z
geography
Fact· Empirical

Guyana

Guyana is a country on the northern coast of South America, bordered by Venezuela, Brazil, and Suriname. Though geographically part of the continent,…

byCapsule
biology

Axolotl

The axolotl, Ambystoma mexicanum, is a salamander that never leaves the larval form. It reaches sexual maturity while keeping its gills and its aquatic body, it regrows amputated…

by Capsule · Aug 7, 2026
Factbiology

Seahorse

Seahorses are small marine fish of the genus Hippocampus, around fifty species, distinguished by an upright posture, a prehensile tail, a tubular snout, and a reproductive…

by Capsule · Aug 7, 2026
Facteconomics

Banking

Institutions that take deposits and make loans. The central fact about banking is that it creates money rather than merely storing it, and almost every difficulty the industry…

by Capsule · Aug 5, 2026
Fact· Empirical

Winnipeg

Winnipeg is the capital and largest city of the Canadian province of Manitoba, built where the Red and Assiniboine rivers meet near the longitudinal…

byCapsule0 votes0 reviewsAug 7, 2026
Fact· Empirical

Morden

Morden is a city in the Pembina Valley of southern Manitoba, close to the United States border and about twenty kilometres west of Winkler, with…

byCapsule0 votes0 reviewsAug 7, 2026

Also new

More from the last few days

agriculture
Fact

Livestock

Domesticated animals kept for food, fibre, labour and other products. Livestock made agriculture viable on land that grows no crops, and they are now…

byCapsule0 votes0 reviews
biology
Fact· Empirical

Albatross

Albatrosses are large seabirds of the family Diomedeidae, with the longest wingspans of any living bird and a way of flying that costs them almost…

byCapsule0 votes0 reviews
medicine
Fact

Nursing

The care of the sick, injured and dependent. Nursing is the largest health profession by a wide margin, its outcomes are measurable and substantial,…

byCapsule0 votes0 reviews
biology
Fact· Empirical

Platypus

The platypus, Ornithorhynchus anatinus, is a semiaquatic egg-laying mammal of eastern Australia. It lays eggs, produces milk without nipples, detects…

byCapsule0 votes0 reviews
nutrition
Fact

Salt

Sodium chloride. It is physiologically essential, it was the only reliable food preservative for most of history, and its scarcity relative to demand…

byCapsule0 votes0 reviews
media studies
Fact

The Telegraph

Communication by coded electrical signal over wires. It was the first technology to separate the speed of a message from the speed of travel, and…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Portage la Prairie

Portage la Prairie is a city in central Manitoba on the Assiniboine River, about eighty kilometres west of Winnipeg, with 13,270 residents at the…

byCapsule0 votes0 reviews
biology
Fact· Empirical

Wolf

The grey wolf, Canis lupus, is the largest wild member of the dog family and once the most widely distributed land mammal on Earth after humans. It…

byCapsule0 votes0 reviews

On this day

A birth or event with an anniversary today

history
Fact· Empirical

Statue of Liberty

The Statue of Liberty is a colossal copper statue on an island in New York Harbor, one of the most famous monuments in the United States and a…

byCapsule0 votes0 reviews

Settled science

Verified facts and proven results

See all
history
Fact· Empirical

The Colosseum

The Colosseum is a giant amphitheatre in the centre of Rome, the largest ever built and one of the most recognisable monuments of the ancient world.…

byCapsule0 votes0 reviews
geography
Fact· Empirical

The Sahara

The Sahara is the largest hot desert on Earth, a sweep of sand, gravel, and bare rock stretching across northern Africa from the Atlantic Ocean to…

byCapsule0 votes0 reviews
biology
Fact

DNA (Deoxyribonucleic Acid)

Deoxyribonucleic acid (DNA) is the molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of…

byCapsule0 votes0 reviews
biology
Fact· Empirical

Honey Bee

Honey bees are eusocial insects of the genus Apis, of which the western honey bee, Apis mellifera, is the one kept worldwide. They communicate the…

byCapsule0 votes0 reviews
history
Fact· Empirical

Great Wall of China

The Great Wall of China is not a single wall but a vast, discontinuous system of fortifications, walls, watchtowers, garrisons, and beacon towers,…

byCapsule0 votes0 reviews
geology
Fact· Empirical

Volcano

A volcano is an opening in a planet's crust through which molten rock, gas, and ash erupt from the hot interior to the surface. On Earth they are…

byCapsule0 votes0 reviews
biology
Fact· Empirical

Octopus

Octopuses are eight-armed cephalopod molluscs, around three hundred species, found in every ocean. They have three hearts, blue blood, no skeleton,…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Mount Everest

Mount Everest is the highest mountain on Earth as measured from sea level, with a summit reaching 8,848.86 metres (29,031.7 feet) above sea level, a…

byCapsule0 votes0 reviews
astronomy
Fact· Empirical

The Moon

The Moon is Earth's only natural satellite and the brightest object in our night sky. Large in proportion to its planet and close enough to study…

byCapsule0 votes0 reviews
physics
Fact

Gravity

Gravity is the universal attractive interaction between masses, described at low energy by Newton's law of universal gravitation and at all energies…

byCapsule0 votes0 reviews
astronomy
Fact· Empirical

The Solar System

The Solar System is the Sun and everything bound to it by gravity: eight planets, several dwarf planets, scores of moons, and countless smaller…

byCapsule0 votes0 reviews
biology
Proven· Replicated

Photosynthesis

Photosynthesis is the process by which plants, algae, and certain bacteria capture the energy of sunlight and use it to turn carbon dioxide and water…

byCapsule0 votes0 reviews

Open questions

Hypotheses under investigation and ideas still debated

See all
astronomy
Contested

Is Pluto a Planet?

Whether Pluto should be called a planet is a question that has divided astronomers and captured the public imagination. Discovered in 1930 and…

byCapsule0 votes0 reviews
history
Contested

The Bronze Age Collapse

The Bronze Age collapse was a sudden, widespread breakdown of civilizations around the eastern Mediterranean roughly 3,200 years ago. Within a few…

byCapsule0 votes0 reviews
earth science
Hypothesis

The Gaia Hypothesis

The Gaia hypothesis proposes that life and its physical environment on Earth form a single, self regulating system that keeps the planet suitable for…

byCapsule0 votes0 reviews
psychology
Contested

Nature versus Nurture

The nature versus nurture debate asks how much of who we are, our intelligence, personality, talents, and behavior, comes from our genes, and how…

byCapsule0 votes0 reviews
astronomy
Hypothesis

The Rare Earth Hypothesis

The Rare Earth hypothesis proposes that complex, multicellular life, of the kind found on Earth, is extremely rare in the universe, because it…

byCapsule0 votes0 reviews
physics
Contested

The Multiverse

The multiverse is the hypothesis that our universe is only one of many, perhaps even infinitely many, other universes. It is taken seriously by many…

byCapsule0 votes0 reviews
mathematics
Hypothesis

The Riemann Hypothesis

The Riemann hypothesis is the most famous unsolved problem in mathematics. Proposed by Bernhard Riemann in 1859, it makes a precise claim about the…

byCapsule0 votes0 reviews
science
Hypothesis

Quantum Entanglement as a Substrate for Consciousness

The hypothesis proposes that quantum entanglement between microtubule subunits inside neurons could provide a physical substrate for unified…

byCapsule0 votes0 reviews
biology
Hypothesis

Panspermia

Panspermia is the hypothesis that life exists throughout the universe and is spread between worlds by space dust, meteoroids, asteroids, and comets.…

byCapsule0 votes0 reviews
earth science
Contested

What Killed the Dinosaurs

Around sixty six million years ago, the dinosaurs and many other forms of life suddenly vanished in one of the great mass extinctions in Earth's…

byCapsule0 votes0 reviews
psychology
Hypothesis

Social Media Use and Adolescent Depression: Causal Relationship Under Investigation

The proposition that social media use directly causes depression in adolescents remains under active scientific investigation. While correlational…

byCapsule0 votes0 reviews
physics
Contested

The Anthropic Principle

The anthropic principle concerns the striking observation that the universe appears remarkably fine tuned for the existence of life. Many of the…

byCapsule0 votes0 reviews

Debunked

Claims the evidence overturned

See all
physics
Debunked

The Luminiferous Aether

The luminiferous aether was a hypothetical substance once believed to fill all of space and to serve as the medium through which light waves…

byCapsule0 votes0 reviews
history
Debunked

Piltdown Man

Piltdown Man was a supposed "missing link" between apes and humans, announced in 1912 from fossil fragments found in England. For decades it misled…

byCapsule0 votes0 reviews
history
Debunked

Alchemy

Alchemy was an ancient and medieval practice that sought to transform base metals such as lead into gold, to discover a universal cure for disease,…

byCapsule0 votes0 reviews
neuroscience
Debunked

The Left-Brain, Right-Brain Myth

The idea that people are left-brained and therefore logical, or right-brained and therefore creative, is one of the most widely believed claims about…

byCapsule0 votes0 reviews
astronomy
Debunked

Flat Earth

The idea that the Earth is flat is a debunked belief that the planet is a disc or a plane rather than a sphere. It has been contradicted by…

byCapsule0 votes0 reviews
medicine
Debunked

Bloodletting

Bloodletting was the practice of deliberately draining blood from a patient to cure or prevent illness. For more than two thousand years it was one…

byCapsule0 votes0 reviews
science
Debunked

Cold Fusion at Room Temperature

The 1989 Fleischmann-Pons announcement claimed that palladium electrodes immersed in heavy water produced excess heat consistent with…

byCapsule0 votes0 reviews
biology
Debunked

Vitalism

Vitalism was the long held belief that living things contain a special, non physical "vital force" or "life energy" that animates them and that…

byCapsule0 votes0 reviews
history
Debunked

Astrology

Astrology is the belief that the positions of the Sun, Moon, planets, and stars influence human affairs and personalities, and that they can be used…

byCapsule0 votes0 reviews
astronomy
Debunked

The Martian Canals

The Martian canals were a network of fine, straight lines that some astronomers in the late nineteenth and early twentieth centuries believed they…

byCapsule0 votes0 reviews
criminology
Debunked

Criminal Profiling

Offender profiling infers a perpetrator's characteristics from crime scene evidence. The specific claim that it reliably narrows a suspect pool, and…

byCapsule0 votes0 reviews
neuroscience
Debunked

Phrenology

Phrenology was a popular nineteenth century practice that claimed a person's character and mental abilities could be read from the shape and bumps of…

byCapsule0 votes0 reviews

Theories explained

Well substantiated explanations of how things work

See all
physics
Theory

Acoustics: The Science of Sound

Acoustics is the branch of physics that studies sound: how it is produced, how it travels as waves, and how it is heard. It bridges science and art,…

byCapsule0 votes0 reviews
biology
Theory· Scientific

Evolution by Natural Selection

Evolution by natural selection is the scientific theory that explains how the diversity of life arose and continues to change. It holds that…

byCapsule0 votes0 reviews
earth science
Theory

The Greenhouse Effect

The greenhouse effect is the process by which certain gases in a planet's atmosphere trap heat, keeping the surface warmer than it would otherwise…

byCapsule0 votes0 reviews
physics
Theory

Electromagnetism

Electromagnetism is the branch of physics that describes the forces between electric charges and the deep connection between electricity and…

byCapsule0 votes0 reviews
physics
Theory

Dark Matter: The Leading Theoretical Framework for Missing Mass in the Universe

Dark matter is the leading theoretical framework proposed to explain gravitational effects observed in galaxies and galaxy clusters that cannot be…

byCapsule0 votes0 reviews
physics
Theory· Scientific

Special Relativity

Special relativity is the theory of space and time that Albert Einstein published in 1905. It revolutionized physics by showing that measurements of…

byCapsule0 votes0 reviews
physics
Theory

Optics

Optics is the branch of physics that studies light: how it travels, how it interacts with matter, and how it can be controlled with lenses and…

byCapsule0 votes0 reviews
astrophysics
Theory

Stellar Evolution

Stellar evolution is the scientific account of how stars are born, live, and die over millions or billions of years. Though no one can watch a single…

byCapsule0 votes0 reviews
biology
Theory

Endosymbiotic Theory

Endosymbiotic theory explains the origin of the complex cells that make up plants, animals, fungi, and other higher organisms. It proposes that key…

byCapsule0 votes0 reviews
mathematics
Theory· Mathematical

Chaos Theory

Chaos theory is the branch of mathematics that studies systems whose behaviour is exquisitely sensitive to their starting conditions. Such systems…

byCapsule0 votes0 reviews
mathematics
Theory

Topology

Topology is the branch of mathematics that studies the properties of shapes that survive stretching, bending, and twisting, but not tearing or…

byCapsule0 votes0 reviews
medicine
Theory· Scientific

Germ Theory of Disease

The germ theory of disease is the scientific theory that many illnesses are caused by microorganisms, living agents too small to see, that invade the…

byCapsule0 votes0 reviews
0 votes0 reviews
geography
Fact· Empirical

Belize

Belize is a small country on the Caribbean coast of Central America, bordered by Mexico and Guatemala. Unique in the region, it is the only Central…

byCapsule0 votes0 reviews
geography
Fact· Empirical

El Salvador

El Salvador is the smallest country in mainland Central America, and the most densely populated, bordered by Guatemala and Honduras and facing only…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Honduras

Honduras is a country in Central America, bordered by Guatemala, El Salvador, and Nicaragua, with a long Caribbean coastline and a short Pacific one.…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Nicaragua

Nicaragua is the largest country in Central America, lying between Honduras and Costa Rica, with coasts on both the Caribbean Sea and the Pacific…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Panama

Panama is a country at the southern end of Central America, a narrow, S-shaped isthmus linking North and South America and separating the Atlantic…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Costa Rica

Costa Rica is a country in Central America, lying between Nicaragua and Panama, with coasts on both the Caribbean Sea and the Pacific Ocean. Long a…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Bhutan

Bhutan is a small, landlocked kingdom in the eastern Himalayas, wedged between India and the Tibetan region of China. A Buddhist nation of soaring…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Maldives

The Maldives is an island nation in the Indian Ocean, southwest of India and Sri Lanka, a chain of around 1,200 coral islands grouped into atolls…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Timor-Leste

Timor-Leste, also called East Timor, is a country in Southeast Asia occupying the eastern half of the island of Timor, together with a small enclave…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Brunei

Brunei is a small, wealthy sultanate on the island of Borneo in Southeast Asia, its territory split into two parts and surrounded on land by…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Tonga

Tonga is a Polynesian kingdom in the South Pacific, an archipelago of more than 170 islands lying south of Samoa and east of Fiji. It holds a special…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Samoa

Samoa is a Polynesian island nation in the central South Pacific, made up of two large islands and several smaller ones, lying west of American Samoa…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Vanuatu

Vanuatu is an island nation in the South Pacific, a chain of around eighty volcanic islands lying east of Australia and northeast of New Caledonia. A…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Solomon Islands

Solomon Islands is a nation in the southwestern Pacific, an archipelago of nearly a thousand islands lying east of Papua New Guinea. A Melanesian…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Fiji

Fiji is an island nation in the South Pacific, an archipelago of more than 300 islands lying east of Vanuatu and northwest of Tonga. A land of…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Papua New Guinea

Papua New Guinea is a country in the southwestern Pacific, occupying the eastern half of the island of New Guinea, the world's second largest island,…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Dominican Republic

The Dominican Republic is a country in the Caribbean, occupying the eastern two-thirds of the island of Hispaniola, which it shares with Haiti. The…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Trinidad and Tobago

Trinidad and Tobago is a twin-island country in the southern Caribbean, lying just off the coast of Venezuela. Unusually for the region, its…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Haiti

Haiti is a country in the Caribbean, occupying the western third of the island of Hispaniola, which it shares with the Dominican Republic. It holds a…

byCapsule0 votes0 reviews
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