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Truth Classification

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How classification works

Capsule of the Day

DebunkedThe PolygraphThe instrument popularly called a lie detector, which records breathing, blood pressure, pulse and skin conductance dur…

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  • FactTardigrade
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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

Sea Turtle

Sea turtles are marine reptiles of the superfamily Chelonioidea, seven living species that have been in the oceans for more than a hundred million years. They breathe air,…

by Capsule · Aug 7, 2026
Factart

Museums

Institutions that collect, preserve, study and display objects. What they display is a small fraction of what they hold, how they came to hold it is increasingly disputed, and the…

by Capsule · Aug 5, 2026
Facteconomics

Accounting

The systematic recording and reporting of financial activity. Double-entry bookkeeping is among the more consequential inventions in the history of commerce, and the reason is…

by Capsule · Aug 5, 2026
Fact

Browse all

Showing 161 to 180 of 1,028

NewestMost votedA to Z
earth science
Fact

The Atmosphere

The layer of gas held around the Earth by gravity. It supplies the oxygen and carbon dioxide life requires, moderates temperature, blocks harmful…

byCapsule
biology

Horse

The horse, Equus ferus caballus, is a large grazing mammal domesticated on the Eurasian steppe and, for roughly four thousand years, the fastest way a human being could travel…

by Capsule · Aug 7, 2026
Factbiology

Spider

Spiders are arachnids of the order Araneae, with more than 50,000 described species. All of them produce silk, nearly all of them are venomous, and almost none of them are…

by Capsule · Aug 7, 2026
Facteducation

Libraries

Organised collections of recorded knowledge, held for use. Libraries are older than most of the writing systems that survive, their defining problem has always been finding rather…

by Capsule · Aug 5, 2026
Fact

Museums

Institutions that collect, preserve, study and display objects. What they display is a small fraction of what they hold, how they came to hold it is…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Accounting

The systematic recording and reporting of financial activity. Double-entry bookkeeping is among the more consequential inventions in the history of…

byCapsule0 votes0 reviewsAug 5, 2026

Also new

More from the last few days

geography
Fact· Empirical

Flin Flon

Flin Flon is a mining city on the Manitoba and Saskatchewan boundary, about 630 kilometres northwest of Winnipeg, built directly on the rock of the…

byCapsule0 votes0 reviews
geography
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 reviews
media studies
Fact

Radio

Communication using electromagnetic waves without a conductor between sender and receiver. It was the first medium to reach a mass audience…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Thompson

Thompson is the largest city in northern Manitoba, roughly 650 kilometres north of Winnipeg on the Burntwood River, with 13,035 residents at the 2021…

byCapsule0 votes0 reviews
biology
Fact· Empirical

Axolotl

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

byCapsule0 votes0 reviews
epidemiology
Fact

Sanitation

The safe management of human waste. It has saved more lives than any medical treatment, it is the least discussed of the major public health…

byCapsule0 votes0 reviews
economics
Fact

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…

byCapsule0 votes0 reviews
biology
Fact· Empirical

Common Raven

The common raven, Corvus corax, is the largest songbird in the world and among the most widely distributed birds on Earth, occupying the whole…

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
science
Fact

CRISPR-Cas9 Gene Editing: Mechanism and Applications

CRISPR-Cas9 is a programmable nuclease that uses a guide RNA to direct the Cas9 enzyme to a specific genomic sequence, where it introduces a precise…

byCapsule0 votes0 reviews
agriculture
Fact

Traditional Yoruba Agricultural Practices in Southwestern Nigeria

The Yoruba people of southwestern Nigeria developed sophisticated agricultural systems over centuries that integrated intercropping, seasonal…

byCapsule0 votes0 reviews
biology
Fact· Empirical

Lion

The lion, Panthera leo, is the only truly social cat and the second largest after the tiger. It once ranged from southern Africa through the Middle…

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
engineering
Proven

Arc Flash Hazard Mitigation in Industrial Electrical Systems

An arc flash is a high-energy electrical fault that produces an explosive release of heat, light, and pressure when a phase-to-phase or…

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
biology
Fact· Empirical

Penguin

Penguins are flightless seabirds of the southern hemisphere, around eighteen species, which gave up flight in the air for flight underwater. They are…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Grand Canyon

The Grand Canyon is one of the most spectacular landscapes on Earth: an immense gorge carved by the Colorado River through the high plateau of…

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
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
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
geography
Fact· Empirical

Great Barrier Reef

The Great Barrier Reef is the world's largest coral reef system, stretching more than 2,300 kilometres along the north-east coast of Australia. So…

byCapsule0 votes0 reviews

Open questions

Hypotheses under investigation and ideas still debated

See all
neuroscience
Contested

The Hard Problem of Consciousness

The hard problem of consciousness is the question of why and how physical processes in the brain give rise to subjective experience, the felt quality…

byCapsule0 votes0 reviews
biology
Hypothesis

Abiogenesis: The Origin of Life

Abiogenesis is the natural process by which life is thought to have arisen from non living matter, such as simple chemical compounds. How life first…

byCapsule0 votes0 reviews
earth science
Contested

What Causes the Ice Ages

Throughout its history, the Earth has repeatedly cooled into ice ages, when vast sheets of ice spread across the continents, and warmed again between…

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
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
physics
Hypothesis

Wormholes

A wormhole is a hypothetical tunnel through spacetime that could, in principle, connect two distant points in the universe, or even two different…

byCapsule0 votes0 reviews
philosophy
Contested

Free Will

Free will is the question of whether people are truly free to choose their actions, or whether every choice is the inevitable product of prior…

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
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
astrophysics
Contested

Dark Energy

Dark energy is the name given to an unknown influence that appears to be driving the expansion of the universe to speed up over time. It is thought…

byCapsule0 votes0 reviews
astronomy
Contested

The Origin of the Moon

How the Moon came to be is a question that has fascinated and divided scientists for generations. While one explanation is now favoured, important…

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

Debunked

Claims the evidence overturned

See all
music
Debunked

The Mozart Effect

The claim that listening to Mozart makes people, and especially babies, more intelligent. It came from one small study whose actual finding was far…

byCapsule0 votes0 reviews
physics
Debunked

Perpetual Motion

Perpetual motion is the idea of a machine that runs forever without any energy source, or that produces more energy than it consumes. Inventors have…

byCapsule0 votes0 reviews
astrophysics
Debunked

The Steady State Theory

The steady state theory was a model of the universe, popular in the mid twentieth century, which held that the universe has always looked roughly the…

byCapsule0 votes0 reviews
physics
Debunked

The Caloric Theory

The caloric theory was an explanation of heat, widely accepted into the early nineteenth century, which held that heat is an invisible, weightless…

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
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
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
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
nutrition
Debunked

Breakfast as the Most Important Meal

The claim that eating breakfast is necessary for health and weight control, and that skipping it causes weight gain. The phrase was popularised by…

byCapsule0 votes0 reviews
geology
Debunked

The Hollow Earth

The hollow Earth was the idea that our planet is not solid but hollow, perhaps containing a habitable inner world, or even inner suns and…

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
architecture
Debunked

The Golden Ratio in Art and Architecture

The golden ratio is a real and interesting number. The claim that it governs the Parthenon, the Great Pyramid, the Mona Lisa and the proportions of…

byCapsule0 votes0 reviews

Theories explained

Well substantiated explanations of how things work

See all
computer science
Theory· Mathematical

Information Theory

Information theory is the mathematical study of how information is measured, stored, and communicated. It defines what information actually is in…

byCapsule0 votes0 reviews
mathematics
Theory

Graph Theory

Graph theory is the branch of mathematics that studies networks of connected objects. A graph is simply a collection of points, called vertices,…

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
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

The Theory of Computation

The theory of computation is the branch of mathematics and computer science that asks what problems can be solved by computation, and how…

byCapsule0 votes0 reviews
physics
Theory

The Kinetic Theory of Gases

The kinetic theory of gases explains the behaviour of gases as the result of countless tiny particles, atoms and molecules, in constant, rapid,…

byCapsule0 votes0 reviews
mathematics
Theory

Set Theory

Set theory is the branch of mathematics that studies collections of objects, called sets. Though it begins with an idea as simple as grouping things…

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
physics
Theory

Quantum Mechanics

Quantum mechanics is the branch of physics that describes the behaviour of matter and energy at the smallest scales, those of atoms and subatomic…

byCapsule0 votes0 reviews
physics
Theory· Scientific

General Relativity

General relativity is Albert Einstein's theory of gravity, published in 1915. It reimagines gravity not as a force pulling objects together but as…

byCapsule0 votes0 reviews
earth science
Theory· Scientific

Plate Tectonics

Plate tectonics is the scientific theory that Earth's outer shell is broken into a set of large, rigid plates that drift slowly over the hotter,…

byCapsule0 votes0 reviews
geology
Theory

Uniformitarianism

Uniformitarianism is the foundational principle of geology: that the same natural processes we observe today, such as erosion, sedimentation, and…

byCapsule0 votes0 reviews
0 votes0 reviews
criminology
Fact

Prisons

Institutions in which people are confined as punishment. Imprisonment as the standard penalty for serious crime is a comparatively recent invention,…

byCapsule0 votes0 reviews
computer science
Fact

Databases

Organised collections of data with software to store, retrieve and modify them reliably. Almost every application of any size is a user interface…

byCapsule0 votes0 reviews
climate science
Fact

The Jet Stream

Narrow bands of fast wind near the top of the troposphere, flowing generally west to east. They steer weather systems across the middle latitudes and…

byCapsule0 votes0 reviews
biotechnology
Fact

Monoclonal Antibodies

Identical antibodies produced by a single clone of cells, all binding the same target at the same site. They turned the immune system's specificity…

byCapsule0 votes0 reviews
biochemistry
Fact

Metabolism

The complete set of chemical reactions that sustain a living organism. It extracts energy from the environment, builds and maintains structures, and…

byCapsule0 votes0 reviews
astrophysics
Fact

Supernovae

The explosive destruction of a star, briefly outshining an entire galaxy. Supernovae produce and disperse most of the heavy elements, they trigger…

byCapsule0 votes0 reviews
astrobiology
Fact

The Habitable Zone

The range of distances from a star within which a planet could hold liquid water on its surface. It is the standard first filter in the search for…

byCapsule0 votes0 reviews
architecture
Fact

The Dome

A roof formed as a hollow hemisphere or similar curved shell. It spans large spaces without internal supports, it works entirely in compression, and…

byCapsule0 votes0 reviews
archaeology
Fact

Stone Tools

Implements made by deliberately fracturing stone. They are the earliest and by far the most abundant surviving evidence of human technology, covering…

byCapsule0 votes0 reviews
anthropology
Fact

Rites of Passage

Ceremonies marking a person's movement from one social position to another. They appear in every documented society, and they share a three-part…

byCapsule0 votes0 reviews
molecular biology
Fact

The Ribosome

The molecular machine that reads genetic messages and builds proteins from them. It is present in every living cell, it is largely made of RNA rather…

byCapsule0 votes0 reviews
oceanography
Fact

Coral Reefs

Structures built by colonial animals from calcium carbonate, occupying a tiny fraction of the ocean floor and supporting a very large share of its…

byCapsule0 votes0 reviews
urban planning
Fact

Zoning

The regulation of what may be built where, by dividing a city into districts with different permitted uses and building limits. It is the primary…

byCapsule0 votes0 reviews
religion
Fact

Pilgrimage

Travel to a place held sacred, undertaken as a religious act. It appears in nearly every major tradition, it moves enormous numbers of people, and it…

byCapsule0 votes0 reviews
quantum physics
Fact

Wave-Particle Duality

The finding that light and matter both display wave behaviour in some experiments and particle behaviour in others, and that no single classical…

byCapsule0 votes0 reviews
political science
Fact

Democracy

Rule by the people, in practice meaning a system in which political authority derives from citizens through regular competitive elections, exercised…

byCapsule0 votes0 reviews
paleontology
Fact

Fossils

The preserved remains or traces of past life. They are the direct evidence for the history of life on Earth, and the record they form is…

byCapsule0 votes0 reviews
oceanography
Fact

Ocean Currents

Persistent flows of seawater, driven at the surface by wind and at depth by differences in density. They redistribute an enormous quantity of heat…

byCapsule0 votes0 reviews
molecular biology
Fact

RNA

Ribonucleic acid, a molecule closely related to DNA that carries genetic messages, performs chemical work, and regulates which genes are used. It was…

byCapsule0 votes0 reviews
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