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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

Factbiology

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
Factagriculture

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 the resource has been repeatedly…

by Capsule · Aug 5, 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 61 to 80 of 1,028

NewestMost votedA to Z
engineering
Fact

Aviation

Powered flight through the atmosphere. It went from first sustained flight to routine intercontinental travel within sixty years, and its safety…

byCapsule
biology

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
Factbiology

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

Platypus

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

by Capsule · Aug 7, 2026
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 reviewsAug 5, 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

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
art
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 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
biology
Fact· Empirical

Seahorse

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

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
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
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
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

Settled science

Verified facts and proven results

See all
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
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
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
astronomy
Fact· Empirical

Black Hole

A black hole is a region of space where gravity is so intense that nothing, not even light, can escape once it passes a certain boundary. They are…

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
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
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
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
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
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
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

Open questions

Hypotheses under investigation and ideas still debated

See all
astronomy
Contested

The Fermi Paradox

The Fermi paradox is the puzzling contrast between the high apparent likelihood that alien civilizations exist somewhere in our vast galaxy and the…

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
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
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
astrophysics
Contested

How the Universe Will End

The ultimate fate of the universe is one of the deepest questions in science. Cosmologists have proposed several very different endings, and which…

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
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
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
astronomy
Hypothesis

Planet Nine

Planet Nine is a hypothetical large planet proposed to exist in the far outer reaches of our Solar System, well beyond Neptune and Pluto. It has…

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
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

Debunked

Claims the evidence overturned

See all
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
education
Debunked

Learning Styles

The idea that each person learns best through a particular sensory channel, and that teaching matched to that channel improves learning. It is…

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
medicine
Debunked

Do Vaccines Cause Autism?

The claim that vaccines cause autism is one of the most damaging medical myths of modern times. It has been investigated exhaustively and thoroughly…

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
geology
Debunked

The Expanding Earth

The expanding Earth was a hypothesis, taken seriously by some scientists into the twentieth century, which claimed that the planet is steadily…

byCapsule0 votes0 reviews
literature
Debunked

The Shakespeare Authorship Question

The claim that the works attributed to William Shakespeare were written by someone else. It has attracted eminent supporters for a hundred 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
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
chemistry
Debunked

Phlogiston Theory

Phlogiston theory was an early explanation of combustion, widely accepted in the seventeenth and eighteenth centuries. It held that all flammable…

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
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
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
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
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
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
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
physics
Theory· Emerging

String Theory

String theory is a theoretical framework that attempts to unify all the forces and particles of nature, including gravity, into a single description.…

byCapsule0 votes0 reviews
astronomy
Theory· Scientific

The Big Bang

The Big Bang is the prevailing cosmological theory of how the universe began. It holds that the universe started about 13.8 billion years ago in an…

byCapsule0 votes0 reviews
mathematics
Theory· Mathematical

Game Theory

Game theory is the mathematical study of strategic decision making, where the outcome for each participant depends not only on their own choice but…

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
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
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
0 votes0 reviews
engineering
Fact

The Electricity Grid

The network generating, transmitting and distributing electrical power. It is the largest machine ever built, it must balance supply and demand…

byCapsule0 votes0 reviews
engineering
Fact

Railways

Vehicles running on fixed guided tracks. The essential idea is older than the steam engine, and what railways did to distance, time and settlement…

byCapsule0 votes0 reviews
urban planning
Fact

Housing

Dwellings and the systems producing and allocating them. Housing is simultaneously shelter, the largest household expense in most countries, and the…

byCapsule0 votes0 reviews
science
Fact

Units of Measurement

Defined quantities against which other quantities are compared. Their standardisation is a precondition for trade, engineering and science, and the…

byCapsule0 votes0 reviews
religion
Fact

Religious Festivals

Recurring celebrations marking events in a religious calendar. They structure time, transmit tradition, and are among the most widely observed…

byCapsule0 votes0 reviews
quantum physics
Fact

The Photon

The quantum of the electromagnetic field, the smallest possible amount of light at a given frequency. It has no mass, always travels at the speed of…

byCapsule0 votes0 reviews
political science
Fact

Federalism

A system in which authority is divided between a central government and regional governments, each with powers that the other cannot unilaterally…

byCapsule0 votes0 reviews
philosophy
Fact

Ethics

The systematic study of how one ought to act. It asks what makes an action right, what makes a life good, and what grounds those judgements, and its…

byCapsule0 votes0 reviews
oceanography
Fact

Plankton

Organisms that drift in water rather than swimming against currents. They include the base of the marine food web and produce a large share of the…

byCapsule0 votes0 reviews
molecular biology
Fact

Gene Regulation

The control of which genes are expressed, when, and how strongly. Every cell in an organism carries the same genome, so what distinguishes a neuron…

byCapsule0 votes0 reviews
microbiology
Fact

Viruses

Infectious agents consisting of genetic material inside a protein coat, which reproduce only inside living cells. They are the most numerous…

byCapsule0 votes0 reviews
media studies
Fact

Censorship

The suppression of speech, writing or images by an authority. It is as old as writing, its methods have changed with each communication technology,…

byCapsule0 votes0 reviews
epidemiology
Fact

Medical Screening

Testing people without symptoms to detect disease early. It saves lives in specific programmes and causes harm in others, and distinguishing between…

byCapsule0 votes0 reviews
earth science
Fact

Weather Forecasting

Predicting atmospheric conditions from measurements of the present state. It became genuinely accurate only in the past few decades, and its…

byCapsule0 votes0 reviews
criminology
Fact

Organised Crime

Criminal activity carried out by durable groups organised for profit. It differs from individual offending in being structured, continuing beyond its…

byCapsule0 votes0 reviews
climate science
Fact

The Carbon Cycle

The movement of carbon between the atmosphere, oceans, land and rock. It operates on two timescales that differ by a factor of millions, and human…

byCapsule0 votes0 reviews
biotechnology
Fact

Synthetic Biology

The design and construction of biological systems that do not exist in nature, treating cells as programmable manufacturing platforms. It applies…

byCapsule0 votes0 reviews
biochemistry
Fact

Hormones

Chemical messengers released into the bloodstream by one tissue to act on another. They coordinate processes across the whole body over minutes to…

byCapsule0 votes0 reviews
astrophysics
Fact

Galaxies

Gravitationally bound systems of stars, gas, dust and dark matter. They are the units in which the visible matter of the universe is organised, and…

byCapsule0 votes0 reviews
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