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Truth Classification

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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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The library

Capsules

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

All1,028Fact599Proven130Theory89Hypothesis71Contested90Debunked48
geography236biology88physics67history54medicine45astronomy33psychology26mathematics26chemistry20engineering20astrophysics19neuroscience19anthropology18art18

Trending now

Most recent activity

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
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
Factbiology

Salmon

Salmon are anadromous fish of the family Salmonidae: born in fresh water, grown at sea, and returning to fresh water to spawn, in most cases to the precise stream where they…

by Capsule · Aug 7, 2026
Fact

Browse all

Showing 41 to 60 of 1,028

NewestMost votedA to Z
Fact

Refrigeration

Removing heat from a space to keep it below the surrounding temperature. It is the technology that changed what people eat more than any other, and…

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
Factmedia studies

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 that separation changed news,…

by Capsule · Aug 5, 2026
Factgeography

Selkirk

Selkirk is a city on the Red River about twenty-two kilometres northeast of Winnipeg, with 10,504 residents at the 2021 census. It came close to being the site of the…

by Capsule · Aug 7, 2026
Fact· Empirical

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…

byCapsule0 votes0 reviewsAug 7, 2026
Fact· Empirical

Salmon

Salmon are anadromous fish of the family Salmonidae: born in fresh water, grown at sea, and returning to fresh water to spawn, in most cases to the…

byCapsule0 votes0 reviewsAug 7, 2026

Also new

More from the last few days

biology
Fact· Empirical

Komodo Dragon

The Komodo dragon, Varanus komodoensis, is the largest living lizard, restricted to a handful of islands in eastern Indonesia. It grows to around…

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
economics
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 reviews
economics
Fact

Insurance

The transfer of risk from an individual to a pool in exchange for a payment. It works because large numbers behave predictably even when individuals…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Winkler

Winkler is the fourth-largest city in Manitoba, in the Pembina Valley about twenty kilometres north of the United States border, with 13,745…

byCapsule0 votes0 reviews
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
agriculture
Fact

Fishing

Catching aquatic animals for food. It is the last major food source still taken from the wild at scale, which is precisely why it is the one where…

byCapsule0 votes0 reviews
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

Settled science

Verified facts and proven results

See all
chemistry
Fact

Water (H₂O)

Water is a chemical compound with the formula H₂O, consisting of two hydrogen atoms covalently bonded to one oxygen atom. Its bent molecular geometry…

byCapsule0 votes0 reviews
astronomy
Fact· Empirical

The Sun

The Sun is the star at the centre of the Solar System, a vast sphere of hot plasma whose gravity holds the planets in their orbits and whose light…

byCapsule0 votes0 reviews
biology
Fact· Empirical

Great White Shark

The great white shark, Carcharodon carcharias, is the largest predatory fish, reaching about six metres. It is warm-blooded in a limited and…

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
history
Fact· Historical

French Revolution

The French Revolution (1789–1799) was a period of radical political and social upheaval in France that ended the Bourbon monarchy, abolished feudal…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Canada

Canada is a country in North America, the second-largest in the world by total area, stretching from the Atlantic Ocean in the east to the Pacific in…

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
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
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
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
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
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

Open questions

Hypotheses under investigation and ideas still debated

See all
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
engineering
Contested

Renewable Energy and Electrical Grid Stability

Wind and solar generation are non-dispatchable and produce zero rotational inertia, raising legitimate concerns about frequency regulation and…

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
astronomy
Hypothesis

The Dyson Sphere

A Dyson sphere is a hypothetical megastructure that an extremely advanced civilization might build around a star to capture a large share of its…

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
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
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
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
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
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
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
psychology
Contested

The Origin of Language

How human language first arose is one of the hardest questions in science. That we alone among animals possess full language is clear; when, how, and…

byCapsule0 votes0 reviews

Debunked

Claims the evidence overturned

See all
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
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 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
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
medicine
Debunked

Humorism: The Four Humors

Humorism, or humoral theory, was the belief that human health depends on the balance of four bodily fluids, called humors: blood, phlegm, yellow…

byCapsule0 votes0 reviews
biology
Debunked

Lamarckism

Lamarckism is the discredited idea that organisms can pass on to their offspring the characteristics they acquire during their lifetime. Its classic…

byCapsule0 votes0 reviews
biology
Debunked

Spontaneous Generation

Spontaneous generation was the long held belief that living organisms could arise directly from non living matter. People thought maggots formed from…

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
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
geography
Debunked

The Bermuda Triangle

The Bermuda Triangle is a region of the Atlantic Ocean, roughly between Florida, Bermuda, and Puerto Rico, said to be the site of mysterious…

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

Miasma Theory

Miasma theory was the belief that diseases such as cholera and the plague were caused by "bad air," a poisonous vapor thought to rise from rotting…

byCapsule0 votes0 reviews

Theories explained

Well substantiated explanations of how things work

See all
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
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
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
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
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
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
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

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
physics
Theory

Thermodynamics

Thermodynamics is the branch of physics concerned with heat, energy, and work, and how they transform from one form to another. Its laws are among…

byCapsule0 votes0 reviews
science
Theory

The Gut-Brain Axis: Microbiome Influence on Mental Health

The gut-brain axis describes the bi-directional signalling between gut microbiota and the central nervous system via the vagus nerve, immune system,…

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
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
0 votes0 reviews
Aug 5, 2026
Fact

Canals

Artificial waterways for navigation. Water carries heavy loads at a fraction of the effort land transport requires, and for a period of roughly a…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Roads

Prepared routes for travel over land. Roads are the oldest large-scale infrastructure, the engineering problem they solve is drainage rather than…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Paper

A sheet of matted plant fibre. It replaced every earlier writing surface because it was far cheaper, and the consequences of cheap writing material…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Cartography

The making of maps. Every map is a deliberate distortion, because the surface of a sphere cannot be laid flat without stretching something, and every…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

The Marathon

A running race of 42.195 kilometres. The distance is arbitrary, its founding story is largely legend, and it has become the standard test of…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Creation Myths

Traditional accounts of how the world and its inhabitants came to exist. Every documented culture has one, they fall into a small number of recurring…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Board Games

Games played on a marked surface with pieces. They are among the oldest recorded recreational objects, they appear independently across unconnected…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Clothing

Coverings worn on the body. Clothing is functional, and its functions are only partly physical: almost everywhere it also signals identity, status…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Dance

Movement of the body performed for expression, ritual or social purpose, generally in relation to rhythm. It is present in every documented human…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Sculpture

Three-dimensional art, made by removing material, adding it, or casting it. The method used constrains what can be made, and much of what…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Photography

Recording images by the action of light on a light-sensitive surface. It required two separate discoveries, projecting an image and fixing it…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Textiles

Fabrics made from fibres. Textile production drove the first industrial mechanisation, it remains among the largest manufacturing sectors, and the…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Mining

Extracting minerals from the ground. Every manufactured object contains material that was mined, the industry has been transformed by scale and…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Forestry

The management of forests for timber, other products and ecological function. It is among the oldest forms of resource management, and its central…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Irrigation

Supplying water to crops artificially. It made agriculture possible in places rainfall could not support, it is the largest human use of fresh water,…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Bread

Baked dough of ground grain and water. It is among the oldest prepared foods, it supplies a substantial share of the world's calories, and its…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Timekeeping

Measuring the passage of time and dividing it into units. Every method works by counting something that repeats regularly, and the history of the…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

The Battery

A device storing energy chemically and releasing it as electric current. It made electricity portable, and its energy density is the constraint…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Navigation

Determining position and finding a route. For most of history the difficult part was not direction but position, and specifically longitude, which…

byCapsule0 votes0 reviewsAug 5, 2026
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