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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
Filtered byphysiologyClear all

Results

Showing 1 to 12 of 12

NewestMost votedA to Z
sport
Fact

The Marathon

A running race of 42.195 kilometres. The distance is arbitrary, its founding story is largely legend, and it has become the standard test of…

byCapsule
0 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
medicine
Fact

The Lungs

The organs that bring air into contact with blood so that oxygen can enter and carbon dioxide can leave. They achieve this across a surface roughly…

byCapsule0 votes0 reviews
medicine
Fact

The Liver

The largest internal organ and the most chemically versatile, performing several hundred distinct functions. It is the only human internal organ that…

byCapsule0 votes0 reviews
biology
Proven

Muscle Contraction

Muscle shortens because two sets of protein filaments slide past one another, driven by myosin heads that repeatedly attach to actin, pivot, and let…

byCapsule0 votes0 reviews
medicine
Proven

Blood Clotting

The process that seals a damaged blood vessel, combining a physical plug of platelets with a mesh of fibrin produced by a cascade of enzymes. It has…

byCapsule0 votes0 reviews
biology
Proven

Circadian Rhythms

Almost every organism runs an internal clock with a period of about a day, generated by a molecular feedback loop inside individual cells. It runs…

byCapsule0 votes0 reviews
biology
Proven

Osmosis

Water moves across a membrane from where solutes are dilute to where they are concentrated. It requires no pump and no energy input, it generates…

byCapsule0 votes0 reviews
anthropology
Hypothesis

The Endurance Running Hypothesis

The proposal that humans evolved to run long distances, and that running down prey over hours in the heat was how our ancestors hunted before…

byCapsule0 votes0 reviews
medicine
Proven

The Circulation of the Blood

William Harvey demonstrated in 1628 that blood circulates in a closed loop driven by the heart. He proved it by measurement, against a doctrine that…

byCapsule0 votes0 reviews
neuroscience
Proven

The Action Potential

The electrical pulse a nerve cell uses to signal. It is the unit of communication in every nervous system, its mechanism is understood in…

byCapsule0 votes0 reviews
paleontology
Contested

Were Dinosaurs Warm-Blooded

Whether dinosaurs generated their own body heat, like mammals and birds, or depended on the environment, like modern reptiles, has been argued for…

byCapsule0 votes0 reviews