The anthropic principle, also known as the "observation selection effect", is the hypothesis, first proposed in 1957 by
Robert Dicke
Robert Henry Dicke (; May 6, 1916 – March 4, 1997) was an American astronomer and physicist who made important contributions to the fields of astrophysics, atomic physics, cosmology and gravity. He was the Albert Einstein Professor in Scienc ...
, that there is a restrictive lower bound on how statistically probable our observations of the universe are, because observations could only happen in a universe capable of developing intelligent life. Proponents of the anthropic principle argue that it explains why this universe has the
age
Age or AGE may refer to:
Time and its effects
* Age, the amount of time someone or something has been alive or has existed
** East Asian age reckoning, an Asian system of marking age starting at 1
* Ageing or aging, the process of becoming older ...
and the fundamental physical constants necessary to accommodate conscious life, since if either had been different, we would not have been around to make observations. Anthropic reasoning is often used to deal with the notion that the universe seems to be finely tuned for the existence of life.
There are many different formulations of the anthropic principle. Philosopher
Nick Bostrom
Nick Bostrom ( ; sv, Niklas Boström ; born 10 March 1973) is a Swedish-born philosopher at the University of Oxford known for his work on existential risk, the anthropic principle, human enhancement ethics, superintelligence risks, and the rev ...
counts them at thirty, but the underlying principles can be divided into "weak" and "strong" forms, depending on the types of cosmological claims they entail. The weak anthropic principle (WAP), as defined by
Brandon Carter
Brandon Carter, (born 1942) is an Australian theoretical physicist, best known for his work on the properties of black holes and for being the first to name and employ the anthropic principle in its contemporary form. He is a researcher at t ...
, states that the universe's ostensible fine tuning is the result of
selection bias
Selection bias is the bias introduced by the selection of individuals, groups, or data for analysis in such a way that proper randomization is not achieved, thereby failing to ensure that the sample obtained is representative of the population int ...
(specifically
survivorship bias
Survivorship bias or survival bias is the logical error of concentrating on entities that passed a selection process while overlooking those that did not. This can lead to incorrect conclusions because of incomplete data.
Survivorship bias is ...
). Most such arguments draw upon some notion of the
multiverse
The multiverse is a hypothetical group of multiple universes. Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, information, and the physical laws and constants that describe them. The di ...
for there to be a
statistical population
In statistics, a population is a set of similar items or events which is of interest for some question or experiment. A statistical population can be a group of existing objects (e.g. the set of all stars within the Milky Way galaxy) or a hypoth ...
of universes to select from. However, a single vast universe is sufficient for most forms of the WAP that do not specifically deal with fine tuning. Carter distinguished the WAP from the strong anthropic principle (SAP), which considers the universe in some sense compelled to eventually have conscious and sapient life emerge within it. A form of the latter known as the participatory anthropic principle, articulated by
John Archibald Wheeler
John Archibald Wheeler (July 9, 1911April 13, 2008) was an American theoretical physicist. He was largely responsible for reviving interest in general relativity in the United States after World War II. Wheeler also worked with Niels Bohr in e ...
, suggests on the basis of
quantum mechanics
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ...
that the universe, as a condition of its existence, must be observed, so implying one or more observers. Stronger yet is the final anthropic principle, proposed by
John D. Barrow
John David Barrow (29 November 1952 – 26 September 2020) was an English cosmologist, theoretical physicist, and mathematician. He served as Gresham Professor of Geometry at Gresham College from 2008 to 2011. Barrow was also a writer of pop ...
and
Frank Tipler
Frank Jennings Tipler (born February 1, 1947) is an American mathematical physicist and cosmologist, holding a joint appointment in the Departments of Mathematics and Physics at Tulane University. Tipler has written books and papers on the Omeg ...
, which views the universe's structure as expressible by
bit
The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...
s of
information
Information is an abstract concept that refers to that which has the power to inform. At the most fundamental level information pertains to the interpretation of that which may be sensed. Any natural process that is not completely random ...
in such a way that
information processing
Information processing is the change (processing) of information in any manner detectable by an observer. As such, it is a process that ''describes'' everything that happens (changes) in the universe, from the falling of a rock (a change in posit ...
is inevitable and eternal.
Definition and basis
The principle was formulated as a response to a series of observations that the laws of nature and parameters of the universe take on values that are consistent with conditions for life as we
know
Knowledge can be defined as awareness of facts or as practical skills, and may also refer to familiarity with objects or situations. Knowledge of facts, also called propositional knowledge, is often defined as true belief that is distinc ...
it rather than a set of values that would not be consistent with life on
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. The anthropic principle states that this is a
necessity
Necessary or necessity may refer to:
* Need
** An action somebody may feel they must do
** An important task or essential thing to do at a particular time or by a particular moment
* Necessary and sufficient condition, in logic, something that i ...
, because if life were impossible, no living entity would be there to observe it, and thus would not be known. That is, it must be possible to observe ''some'' universe, and hence, the laws and constants of any such universe must accommodate that possibility.
The term ''
anthropic
{{Short pages monitor
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* 5 chapters availabl online.
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* Stenger, Victor J. (1999), "Anthropic design," ''The Skeptical Inquirer 23'' (August 31, 1999): 40–43
* Mosterín, Jesús (2005). "Anthropic Explanations in Cosmology." In P. Háyek, L. Valdés and D. Westerstahl (ed.), ''Logic, Methodology and Philosophy of Science, Proceedings of the 12th International Congress of the LMPS''. London: King's College Publications, pp. 441–473. .
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* A simple anthropic argument for why there are 3 spatial and 1 temporal dimensions.
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* Shows that some of the common criticisms of AP based on its relationship with numerology or the theological Design Argument are wrong.
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External links
*
Nick Bostrom
Nick Bostrom ( ; sv, Niklas Boström ; born 10 March 1973) is a Swedish-born philosopher at the University of Oxford known for his work on existential risk, the anthropic principle, human enhancement ethics, superintelligence risks, and the rev ...
web site devoted to the Anthropic Principle.
* Friederich, Simon Fine-tuning review article of the discussion about fine-tuning, highlighting the role of the anthropic principles.
* Gijsbers, Victor. (2000) Positive Atheism Magazine.
* Chown, Marcus ''New Scientist'', 6 June 1998. On Max Tegmark's work.
* Stephen Hawking,
Steven Weinberg
Steven Weinberg (; May 3, 1933 – July 23, 2021) was an American theoretical physicist and Nobel laureate in physics for his contributions with Abdus Salam and Sheldon Glashow to the unification of the weak force and electromagnetic interactio ...
,
Alexander Vilenkin
Alexander Vilenkin (russian: Алекса́ндр Виле́нкин; uk, Олександр Віленкін; born 13 May 1949) is the Leonard Jane Holmes Bernstein Professor of Evolutionary Science and Director of the Institute of Cosmology a ...
,
David Gross
David Jonathan Gross (; born February 19, 1941) is an American theoretical physicist and string theorist. Along with Frank Wilczek and David Politzer, he was awarded the 2004 Nobel Prize in Physics for their discovery of asymptotic freedom. Gr ...
and
Lawrence Krauss
Lawrence Maxwell Krauss (born May 27, 1954) is an American theoretical physicist and cosmologist who previously taught at Arizona State University, Yale University, and Case Western Reserve University. He founded ASU's Origins Project, now cal ...
Lee Smolin
Lee Smolin (; born June 6, 1955) is an American theoretical physicist, a faculty member at the Perimeter Institute for Theoretical Physics, an adjunct professor of physics at the University of Waterloo and a member of the graduate faculty of the ...
's theory of cosmological natural selection.
*
Leonard Susskind
Leonard Susskind (; born June 16, 1940)his 60th birthday was celebrated with a special symposium at Stanford University.in Geoffrey West's introduction, he gives Suskind's current age as 74 and says his birthday was recent. is an American physicis ...
and
Lee Smolin
Lee Smolin (; born June 6, 1955) is an American theoretical physicist, a faculty member at the Perimeter Institute for Theoretical Physics, an adjunct professor of physics at the University of Waterloo and a member of the graduate faculty of the ...
The Anthropic Principle – a review.
* Berger, Daniel, 2002, A critique of Barrow & Tipler.
*
Jürgen Schmidhuber
Jürgen Schmidhuber (born 17 January 1963) is a German computer scientist most noted for his work in the field of artificial intelligence, deep learning and artificial neural networks. He is a co-director of the Dalle Molle Institute for Artif ...
Paul Davies
Paul Charles William Davies (born 22 April 1946) is an English physicist, writer and broadcaster, a professor in Arizona State University and Director of BEYOND: Center for Fundamental Concepts in Science. He is affiliated with the Institute ...