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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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  • 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

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
Factgeography

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
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 101 to 120 of 1,028

NewestMost votedA to Z
Fact

Urban Parks

Public open green space within a city, maintained for recreation and amenity. They were created deliberately as a response to industrial urban…

byCapsule
biology

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
Factmedia studies

Radio

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

by Capsule · Aug 5, 2026
Factgeography

Winnipeg

Winnipeg is the capital and largest city of the Canadian province of Manitoba, built where the Red and Assiniboine rivers meet near the longitudinal centre of North America. With…

by Capsule · Aug 7, 2026
Fact· Empirical

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…

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

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

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 reviews
biology
Fact· Empirical

Orca

The orca, Orcinus orca, also called the killer whale, is the largest member of the dolphin family and the most widely distributed mammal on Earth…

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
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
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

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

Settled science

Verified facts and proven results

See all
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

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

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
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
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
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
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
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
Fact· Empirical

Domestic Cat

The domestic cat, Felis catus, is the most numerous small carnivore on Earth, with something over six hundred million individuals. It is also barely…

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
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
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

Open questions

Hypotheses under investigation and ideas still debated

See all
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
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
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
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
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
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
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
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
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
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

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
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

Debunked

Claims the evidence overturned

See all
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
history
Debunked

Piltdown Man

Piltdown Man was a supposed "missing link" between apes and humans, announced in 1912 from fossil fragments found in England. For decades it misled…

byCapsule0 votes0 reviews
astronomy
Debunked

The Geocentric Model

The geocentric model was the ancient belief that the Earth sits motionless at the center of the universe, with the Sun, Moon, planets, and stars all…

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
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
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
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
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
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
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
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
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
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
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· 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
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
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· 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

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

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

Dark Matter: The Leading Theoretical Framework for Missing Mass in the Universe

Dark matter is the leading theoretical framework proposed to explain gravitational effects observed in galaxies and galaxy clusters that cannot be…

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
0 votes0 reviews
Aug 5, 2026
Fact

Sacred Texts

Writings a religious tradition treats as authoritative. What that authority consists of, how the text was fixed, and how it may be interpreted differ…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Quantum Spin

An intrinsic form of angular momentum carried by particles, with no counterpart in classical physics. Nothing is rotating, the quantity is quantised,…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Political Parties

Organisations that seek to place their members in government, generally by contesting elections. They are not mentioned in most founding…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Mass Extinctions

Intervals in which a large proportion of species disappeared worldwide in a geologically short time. Five are conventionally recognised in the past…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Cell Membranes

The boundary enclosing every cell, formed from a double layer of lipid molecules with proteins embedded in it. It defines what is inside the cell,…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Archaea

A domain of single-celled organisms distinct from both bacteria and eukaryotes. Their recognition as a separate branch of life in 1977 restructured…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Advertising

Paid communication intended to promote a product, service or idea. It funds most commercial media, its measured effects are smaller than its cultural…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Disease Surveillance

The continuous collection and analysis of health data to detect outbreaks, monitor trends and guide response. It is the information system on which…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Soil

The layer of weathered mineral material, organic matter, water, air and organisms covering most land surfaces. It supports essentially all…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Policing

The organised enforcement of law and maintenance of public order by a body authorised by the state. Professional police forces are a nineteenth…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Climate Models

Computer simulations of the climate system, built from physical laws and used to understand past climate and project future change. They are the…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Genetically Modified Crops

Plants whose genome has been altered using recombinant DNA techniques. They have been grown commercially since 1996, cover a substantial share of…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Lipids

A class of biological molecules grouped by not dissolving in water. They store energy, form the boundaries of every cell, and act as signalling…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Neutron Stars

The collapsed cores left by massive stars, containing more than the Sun's mass within a sphere about twenty kilometres across. They are the densest…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Biosignatures

Measurable indicators that life is or was present. They are how the search for life beyond Earth is actually conducted, since organisms cannot be…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Pottery

Objects formed from clay and hardened by heat. Pottery is the most abundant artefact in archaeology, it survives almost indefinitely, and it is the…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Correlation

A statistical measure of how far two variables move together. It is among the most widely used quantities in research and among the most widely…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

Steel

An alloy of iron with a small and controlled quantity of carbon. That small addition transforms a soft metal into the most widely used structural…

byCapsule0 votes0 reviewsAug 5, 2026
Fact

The University

An institution of higher education and research, granting degrees. The form originated in medieval Europe, has proved unusually durable, and combines…

byCapsule0 votes0 reviewsAug 5, 2026
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