Capsule
DonateLog inCreate account
Menu

Navigation

  • Main page
  • Capsules
  • Learning
  • Mapping
  • Rankings
  • Organizations
  • Create
  • Forums
  • Research

Interaction

  • Messages
  • Verify
  • Help
  • About Capsule

Display

Appearance

Environment

EnvironmentsDefault
Capsule
Log in

Navigation

  • Main page
  • Capsules
  • Learning
  • Mapping
  • Rankings
  • Organizations
  • Create
  • Forums
  • Research

Interaction

  • Messages
  • Verify
  • Feedback
  • Help
  • About Capsule

Truth Classification

  • Fact
  • Theory
  • Hypothesis
  • Proven
  • Contested
  • Debunked
How classification works

Capsule of the Day

FactSurgeryTreatment by physical intervention in the body. Surgery was limited for millennia not by knowledge of anatomy but by th…

New in the Library

  • FactTardigrade
  • FactMonarch Butterfly
  • FactSpider

Capsule

© 2026 Solis Holdings Group Inc. All rights reserved.

Built by Solis Dev, a technology studio operating under Solis Holdings Group Inc.

  • Policy
  • Terms of Use
  • Methodology
  • Corrections
  • Non-partisanship
  • Transparency
  • Developers
  • About
  • Discord
  • Sitemap

Capsule, the capsule-pill mark, and the clock logo are trademarks of Solis Holdings Group Inc. All content, source code, and design assets are the exclusive property of Solis Holdings Group Inc., unless otherwise noted. Unauthorized reproduction is prohibited.

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
Factart

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 increasingly disputed, and the…

by Capsule · Aug 5, 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
Factnutrition

Browse all

Showing 501 to 520 of 1,028

NewestMost votedA to Z
chemistry
Theory· Scientific

Chemical Bonding

Chemical bonding is the theory of how atoms join together to form the molecules and materials that make up the world. The forces that hold atoms…

byCapsule

Salt

Sodium chloride. It is physiologically essential, it was the only reliable food preservative for most of history, and its scarcity relative to demand made it a strategic commodity…

by Capsule · Aug 5, 2026
Facteconomics

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 do not, and its two persistent…

by Capsule · Aug 5, 2026
Factgeography

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 residents at the 2021 census. Like…

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

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…

byCapsule0 votes0 reviewsAug 7, 2026

Also new

More from the last few days

biology
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 reviews
biology
Fact· Empirical

Chimpanzee

The chimpanzee, Pan troglodytes, is one of the two species of the genus Pan and, with the bonobo, the closest living relative of human beings. It is…

byCapsule0 votes0 reviews
biology
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 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
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
biology
Fact· Empirical

Common Raven

The common raven, Corvus corax, is the largest songbird in the world and among the most widely distributed birds on Earth, occupying the whole…

byCapsule0 votes0 reviews
medicine
Fact

Nursing

The care of the sick, injured and dependent. Nursing is the largest health profession by a wide margin, its outcomes are measurable and substantial,…

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

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

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
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
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
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· 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
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
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
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
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
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
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

Open questions

Hypotheses under investigation and ideas still debated

See all
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
mathematics
Hypothesis

Goldbach's Conjecture

Goldbach's conjecture is one of the oldest and simplest sounding unsolved problems in mathematics. It states that every even whole number greater…

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
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
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
philosophy
Hypothesis

The Simulation Hypothesis

The simulation hypothesis is the proposal that the reality we experience might actually be an artificial simulation, such as an immensely…

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
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
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
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
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
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

Debunked

Claims the evidence overturned

See all
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
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
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
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
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
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
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

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
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
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
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
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

Theories explained

Well substantiated explanations of how things work

See all
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
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

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· 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· 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
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
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
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· 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
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
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
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
0 votes0 reviews
biology
Theory· Scientific

Punctuated Equilibrium

Punctuated equilibrium is a theory about the pace of evolution. It proposes that species tend to remain largely unchanged for long stretches of time,…

byCapsule0 votes0 reviews
ecology
Theory· Scientific

The Theory of Island Biogeography

The theory of island biogeography explains how many species an island will hold, and why. Developed in the 1960s, it proposes that the number of…

byCapsule0 votes0 reviews
economics
Theory· Scientific

Supply and Demand

Supply and demand is the foundational theory of how prices and quantities are set in a market economy. It holds that the price of a good settles at…

byCapsule0 votes0 reviews
physics
Proven· Replicated

Ohm's Law

Ohm's law is the basic rule governing electric circuits. It states that the current flowing through a conductor is directly proportional to the…

byCapsule0 votes0 reviews
mathematics
Proven· Mathematical Proof

The Irrationality of the Square Root of Two

The square root of two, the number which when multiplied by itself gives exactly two, cannot be written as a fraction of two whole numbers. It is, in…

byCapsule0 votes0 reviews
medicine
Proven· Replicated

HIV Causes AIDS

It is established beyond reasonable doubt that AIDS, the acquired immunodeficiency syndrome, is caused by infection with HIV, the human…

byCapsule0 votes0 reviews
chemistry
Proven· Replicated

Water Is H2O

Water is made of molecules, each consisting of two hydrogen atoms joined to a single oxygen atom, the composition captured in the familiar formula…

byCapsule0 votes0 reviews
quantum physics
Theory· Scientific

Quantum Field Theory

Quantum field theory is the framework that combines quantum mechanics with Einstein's special relativity to describe the fundamental particles of…

byCapsule0 votes0 reviews
economics
Theory· Scientific

Comparative Advantage

Comparative advantage is one of the foundational theories of economics. It explains why two parties, whether individuals, businesses, or whole…

byCapsule0 votes0 reviews
astrophysics
Theory· Scientific

Stellar Nucleosynthesis

Stellar nucleosynthesis is the theory explaining where the chemical elements come from. It holds that the stars are the furnaces in which almost all…

byCapsule0 votes0 reviews
psychology
Theory· Scientific

Cognitive Dissonance

Cognitive dissonance is the psychological theory that people feel mental discomfort when they hold two clashing beliefs, or when their actions…

byCapsule0 votes0 reviews
astrophysics
Theory· Scientific

The Formation of the Solar System

The nebular hypothesis is the accepted scientific theory of how the Sun and its planets formed. It holds that the entire Solar System condensed,…

byCapsule0 votes0 reviews
mathematics
Proven· Mathematical Proof

Gödel's Incompleteness Theorems

Gödel's incompleteness theorems are two of the most profound and startling results in the history of mathematics and logic. Proven by the Austrian…

byCapsule0 votes0 reviews
statistics
Proven· Mathematical Proof

The Central Limit Theorem

The central limit theorem is one of the most important results in all of statistics. It explains why the familiar bell shaped curve appears again and…

byCapsule0 votes0 reviews
medicine
Proven· Replicated

Antibiotic Resistance

Antibiotic resistance is the ability of bacteria to survive the drugs designed to kill them. It is one of the most direct and observable examples of…

byCapsule0 votes0 reviews
medicine
Proven· Replicated

The Eradication of Smallpox

Smallpox was one of the deadliest diseases in human history, killing hundreds of millions of people over thousands of years. In 1980 the World Health…

byCapsule0 votes0 reviews
physics
Proven· Replicated

Conservation of Momentum

Conservation of momentum is one of the most fundamental and reliable laws in all of physics. Momentum, the product of an object's mass and its…

byCapsule0 votes0 reviews
psychology
Theory· Scientific

Classical Conditioning

Classical conditioning is the psychological theory describing how a neutral signal, through repeated association, can come to trigger an automatic…

byCapsule0 votes0 reviews
psychology
Theory· Scientific

Attachment Theory

Attachment theory is the psychological theory that human beings are born with a deep need to form close emotional bonds with a few caregivers, and…

byCapsule0 votes0 reviews
Previous1…2425262728…52Next