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Truth Classification

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Capsule of the Day

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

Factgeography

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 2021 census. Its name records…

by Capsule · Aug 7, 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
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

Browse all

Showing 241 to 260 of 1,028

NewestMost votedA to Z
Contested

The Collapse of Easter Island

Whether the people of Rapa Nui destroyed their own society by deforesting the island, or whether the collapse was caused by European contact, disease…

byCapsule
geography

Steinbach

Steinbach is the third-largest city in Manitoba, about sixty kilometres southeast of Winnipeg, with 17,806 residents at the 2021 census. Founded by Mennonite settlers from the…

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
Factmedicine

Surgery

Treatment by physical intervention in the body. Surgery was limited for millennia not by knowledge of anatomy but by three specific obstacles, and the century in which those were…

by Capsule · Aug 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
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 reviewsAug 7, 2026

Also new

More from the last few days

education
Fact

Libraries

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

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
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
biology
Fact· Empirical

Ant

Ants are eusocial insects of the family Formicidae, with over 14,000 described species and an estimated global population around twenty quadrillion…

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
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

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
biology
Fact· Empirical

Bat

Bats, the order Chiroptera, are the only mammals capable of powered flight. There are more than 1,400 species, roughly a fifth of all mammal species,…

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

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
agriculture
Fact

Nitrogen Cycling in Prairie Soils of the Canadian Prairies

Nitrogen cycling in Prairie soils is a well-documented biological and chemical process that determines agricultural productivity across Manitoba,…

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
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
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
geography
Fact· Empirical

Amazon Rainforest

The Amazon Rainforest is the largest tropical rainforest on Earth, a vast sea of green covering some 5.5 million square kilometres across nine South…

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
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
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
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

Open questions

Hypotheses under investigation and ideas still debated

See all
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
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
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
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
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
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
Contested

Are Viruses Alive?

Whether viruses count as living organisms is a question biologists have debated for over a century, and there is still no settled answer. Viruses sit…

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
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
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
biology
Contested

Are Animals Conscious?

Whether animals have conscious experiences, an inner life of feelings and awareness, is a deep and genuinely contested question. That many animals…

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

Debunked

Claims the evidence overturned

See all
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
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
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
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
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
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
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
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
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
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

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

Theories explained

Well substantiated explanations of how things work

See all
biology
Theory

Mendelian Inheritance

Mendelian inheritance is the set of principles describing how traits are passed from parents to offspring through discrete units we now call genes.…

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
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
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

Electromagnetism

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

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
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
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
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
biology
Theory

Cell Theory

Cell theory is one of the foundational ideas of biology. It holds that all living things are made of cells, that the cell is the basic unit of life,…

byCapsule0 votes0 reviews
0 votes0 reviews
Aug 4, 2026
Contested

The Homo Naledi Burial Claim

The claim that Homo naledi, a small-brained hominin, deliberately buried its dead in a South African cave system, and made engravings and used fire…

byCapsule0 votes0 reviewsAug 4, 2026
Contested

Interstellar Objects

Bodies that formed around other stars and are passing through our solar system on unbound trajectories. Three have been found, the first in 2017 and…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Dowsing

The practice of locating underground water, minerals or other targets by walking over ground holding a forked stick or a pair of rods and watching…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

The Polygraph

The instrument popularly called a lie detector, which records breathing, blood pressure, pulse and skin conductance during questioning. It measures…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

The Ten Percent of the Brain Myth

The claim that human beings use only about ten per cent of their brains, and that the remainder is untapped potential. Every method of examining the…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Facilitated Communication

A technique in which an assistant supports the hand or arm of a non-speaking person while they type, said to reveal unsuspected literacy. Controlled…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Subliminal Advertising

The claim that messages flashed too briefly to be consciously seen can compel people to buy things. It rests on a single 1957 demonstration that its…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Mesmerism

Franz Anton Mesmer's doctrine that an invisible universal fluid flows through all bodies, that illness results from its obstruction, and that a…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Radium Quackery

The sale of radioactive substances as general health tonics in the first decades of the twentieth century. Radium was added to water, ointments,…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Lobotomy

The surgical severing of connections to the frontal lobes as a treatment for mental illness. It was performed on tens of thousands of people between…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Autointoxication

The doctrine that waste retained in the large intestine putrefies and poisons the body, causing a wide range of unrelated diseases. It was mainstream…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Stomach Ulcers and Stress

The belief that peptic ulcers are caused by stress, personality and diet, and that they are a chronic condition to be managed rather than cured. Most…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Telegony

The belief that a female's offspring can inherit characteristics from a male she mated with previously, even when he did not father them. It is…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Preformationism

The doctrine that an organism exists fully formed in miniature within the egg or the sperm, and that development is merely the enlargement of a…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Lysenkoism

The agricultural biology of Trofim Lysenko, adopted as official Soviet doctrine from the 1930s to the mid-1960s, which rejected genetics as a…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Recapitulation Theory

Ernst Haeckel's claim that an embryo passes through the adult forms of its ancestors as it develops, summarised as the slogan that ontogeny…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Water Memory

The claim that water retains a biological imprint of substances it once contained, after dilution so extreme that not a single molecule of the…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

The Planet Vulcan

A planet proposed to orbit between Mercury and the Sun, invoked to explain an anomaly in Mercury's orbit, searched for over half a century, and shown…

byCapsule0 votes0 reviewsAug 4, 2026
Debunked

Polywater

A supposed polymeric form of water, reported from the Soviet Union in the 1960s and studied seriously worldwide for about a decade, which turned out…

byCapsule0 votes0 reviewsAug 4, 2026
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