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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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  • 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

Factepidemiology

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 measures, and roughly a fifth of the…

by Capsule · Aug 5, 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
Factbiology

Hummingbird

Hummingbirds, the family Trochilidae, are small nectar-feeding birds of the Americas that hover in sustained flight and run the highest mass-specific metabolic rate of any…

by Capsule · Aug 7, 2026
Fact

Browse all

Showing 641 to 660 of 1,028

NewestMost votedA to Z
geography
Fact· Empirical

Lithuania

Lithuania is a country on the eastern shore of the Baltic Sea, the largest and southernmost of the three Baltic states. A flat, forested land of…

byCapsule
geography

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
Factgeography

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 Canadian Shield. It is one of…

by Capsule · Aug 7, 2026
Factbiology

Ant

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

by Capsule · Aug 7, 2026
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 reviewsAug 5, 2026
Fact· Empirical

Hummingbird

Hummingbirds, the family Trochilidae, are small nectar-feeding birds of the Americas that hover in sustained flight and run the highest mass-specific…

byCapsule0 votes0 reviewsAug 7, 2026

Also new

More from the last few days

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
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
biology
Fact· Empirical

Monarch Butterfly

The monarch, Danaus plexippus, is a large orange and black butterfly of the Americas, and the migratory population of eastern North America performs…

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
biology
Fact· Empirical

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…

byCapsule0 votes0 reviews
biology
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 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
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

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
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
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
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
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
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
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
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

Elephant

Elephants are the largest living land animals, and there are three species rather than the two most references still give. They have the longest…

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
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
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

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
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
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
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
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
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
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
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
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
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
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
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

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
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
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
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
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
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
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
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
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
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

Theories explained

Well substantiated explanations of how things work

See all
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
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

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
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
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
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· 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
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
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
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
0 votes0 reviews
geography
Fact· Empirical

Bulgaria

Bulgaria is a country in southeastern Europe, on the Balkan Peninsula, stretching from mountains and river valleys to a coastline on the Black Sea.…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Slovakia

Slovakia is a landlocked country in Central Europe, a mountainous land of the Carpathians, dense forests, and hundreds of castles. For most of its…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Serbia

Serbia is a landlocked country in the central Balkans of southeastern Europe, where the great river Danube crosses the heart of the continent. A…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Croatia

Croatia is a country in southeastern Europe, curving around its neighbours in a crescent shape from the plains of the interior to a long, indented…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Iceland

Iceland is an island nation in the North Atlantic, near the Arctic Circle, a land of volcanoes, glaciers, geysers, and waterfalls perched on the…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Denmark

Denmark is the southernmost of the Nordic countries, a small kingdom made up of the Jutland peninsula reaching up from continental Europe and…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Finland

Finland is a country in northern Europe, one of the Nordic nations, a land of vast forests and tens of thousands of lakes stretching far into the…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Ireland

Ireland is an island nation in the North Atlantic, off the western coast of Europe, famous for its lush green landscape that has earned it the name…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Romania

Romania is a country in southeastern Europe, where the arc of the Carpathian Mountains meets the great river Danube and the shores of the Black Sea.…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Hungary

Hungary is a landlocked country in Central Europe, set on the broad plains of the Carpathian Basin and divided by the river Danube. Its people, the…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Czech Republic

The Czech Republic, also known as Czechia, is a landlocked country in the heart of Central Europe, made up of the historic lands of Bohemia and…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Portugal

Portugal is a country on the Atlantic coast of the Iberian Peninsula, the westernmost nation of mainland Europe. With one of the oldest fixed borders…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Austria

Austria is a landlocked, mountainous country in Central Europe, lying largely within the Alps. For centuries it was the centre of the mighty Habsburg…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Switzerland

Switzerland is a landlocked country in the heart of Europe, a small Alpine nation famous for its mountains, its long tradition of neutrality, and its…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Belgium

Belgium is a small country in western Europe, a densely populated crossroads where the Germanic and Latin worlds of the continent meet. Its capital,…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Netherlands

The Netherlands is a country in northwestern Europe, famous as a low-lying land much of which sits at or below sea level, reclaimed from water and…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Guatemala

Guatemala is a country in Central America, just south of Mexico, a land of volcanoes, rainforests, and highland lakes. It was a heartland of the…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Bolivia

Bolivia is a landlocked country in the heart of South America, a land of dramatic extremes from the high, cold plateau of the Andes to the steamy…

byCapsule0 votes0 reviews
geography
Fact· Empirical

Ecuador

Ecuador is a country on the northwestern coast of South America, named for the equator that runs through it. Despite its small size, it holds a…

byCapsule0 votes0 reviews
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