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The Sagan standard is the aphorism that "extraordinary claims require extraordinary evidence". It is named for Carl Sagan (pictured), who used the phrase in his 1979 book Broca's Brain. The standard has been described as fundamental to the scientific method and is regarded as encapsulating the basic principles of scientific skepticism. The Sagan standard is similar to Occam's razor in that both prefer simpler explanations to more complex ones. The Sagan standard is often invoked to challenge data and scientific findings, or to criticize pseudoscientific claims. Similar statements were previously made by figures such as Thomas Jefferson in 1808, Pierre-Simon Laplace in 1814, and Théodore Flournoy in 1899. The formulation "Extraordinary claims require extraordinary proof" was used a year prior to Sagan, by scientific skeptic Marcello Truzzi. It has also been argued that philosopher David Hume first fully characterized the principles of the Sagan standard in his 1748 essay "Of Miracles". (Full article...)

The eastern chipmunk (Tamias striatus) is a chipmunk species found in eastern North America. It is a small species, reaching about 30 centimetres (12 in) in length, with a weight of 66 to 150 grams (2.3 to 5.3 oz). It has reddish-brown fur on its upper body and five dark brown stripes contrasting with light brown stripes along its back, ending in a dark tail. The eastern chipmunk can climb trees well, but constructs underground nests with extensive tunnel systems, often with several entrances. Its vocal repertoire consists of five sounds: the chip, the chuck, the trills, the whistle or squeal, and chatter. Trills have been measured to occur at the rate of 130 vibrations per minute. The eastern chipmunk lives a solitary life, except during courtship and mating and for the short period that young spend with their mothers after birth. It sometimes hibernates during the winter. This eastern chipmunk with stuffed cheeks was photographed in Prospect Park in Brooklyn, New York.

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Carl Sagan with a mock-up of a Viking lander

Thoon Kramom

Christopher Nolan

Andrew Watson