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Cosmological natural selection, also called the fecund universes, is a hypothesis proposed by Lee Smolin intended as a scientific alternative to the
anthropic principle The anthropic principle, also known as the "observation selection effect", is the hypothesis, first proposed in 1957 by Robert Dicke, that there is a restrictive lower bound on how statistically probable our observations of the universe are, beca ...
. It addresses the problem of complexity in our universe, which is largely unexplained. The hypothesis suggests that a process analogous to biological natural selection applies at the grandest of scales. Smolin published the idea in 1992 and summarized it in a book aimed at a lay audience called ''
The Life of the Cosmos ''The Life of the Cosmos'' is the debut non-fiction book by American theoretical physicist Lee Smolin. The book was initially published on January 1, 1997 by Oxford University Press. Overview In the book, Smolin details his Fecund universes whi ...
''.


Hypothesis

Black holes have a role in natural selection. In fecund theory a collapsing
black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...
causes the emergence of a new universe on the "other side", whose fundamental constant parameters (masses of elementary particles, Planck constant,
elementary charge The elementary charge, usually denoted by is the electric charge carried by a single proton or, equivalently, the magnitude of the negative electric charge carried by a single electron, which has charge −1 . This elementary charge is a fundame ...
, and so forth) may differ slightly from those of the universe where the black hole collapsed. Each universe thus gives rise to as many new universes as it has black holes. The theory contains the evolutionary ideas of "reproduction" and "mutation" of universes, and so is formally analogous to models of population biology. Alternatively, black holes play a role in cosmological natural selection by reshuffling only some matter affecting the distribution of elementary quark universes. The resulting population of universes can be represented as a distribution of a landscape of parameters where the height of the landscape is proportional to the numbers of black holes that a universe with those parameters will have. Applying reasoning borrowed from the study of fitness landscapes in population biology, one can conclude that the population is dominated by universes whose parameters drive the production of black holes to a local peak in the landscape. This was the first use of the notion of a ''landscape of parameters'' in physics.
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 ...
, who later promoted a similar string theory landscape, stated:
I'm not sure why Smolin's idea didn't attract much attention. I actually think it deserved far more than it got.
However, Susskind also argued that, since Smolin's theory relies on information transfer from the parent universe to the baby universe through a black hole, it ultimately makes no sense as a theory of cosmological natural selection. According to Susskind and many other physicists, the last decade of black hole physics has shown us that no information that goes into a black hole can be lost. Even Stephen Hawking, who was the largest proponent of the idea that information is lost in a black hole, later reversed his position. The implication is that information transfer from the parent universe into the baby universe through a black hole is not conceivable. Smolin has noted that the string theory landscape is not Popper-falsifiable if other universes are not observable. This is the subject of the
Smolin–Susskind debate 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 ...
concerning Smolin's argument: " he
Anthropic Principle The anthropic principle, also known as the "observation selection effect", is the hypothesis, first proposed in 1957 by Robert Dicke, that there is a restrictive lower bound on how statistically probable our observations of the universe are, beca ...
cannot yield any falsifiable predictions, and therefore cannot be a part of science.""Smolin vs. Susskind: The Anthropic Principle"
'' Edge'' (August 18, 2004)
There are then only two ways out: traversable wormholes connecting the different parallel universes, and "signal nonlocality", as described by Antony Valentini, a scientist at the Perimeter Institute. In a critical review of ''The Life of the Cosmos'', astrophysicist
Joe Silk Joseph Ivor Silk Fellow of the Royal Society, FRS (born 3 December 1942) is a British-American astrophysicist. He was the Savilian Chair of Astronomy at the University of Oxford from 1999 to September 2011. He is an Emeritus Fellow of New C ...
suggested that our universe falls short by about four orders of magnitude from being maximal for the production of
black holes A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can def ...
. In his book ''
Questions of Truth ''Questions of Truth'' is a book by John Polkinghorne and Nicholas Beale which offers their responses to 51 questions about science and religion. The foreword is contributed by Antony Hewish. The book was launched at a workshop at the 2009 Am ...
'', particle physicist
John Polkinghorne John Charlton Polkinghorne (16 October 1930 – 9 March 2021) was an English theoretical physicist, theologian, and Anglican priest. A prominent and leading voice explaining the relationship between science and religion, he was professor of ma ...
puts forward another difficulty with Smolin's thesis: one cannot impose the consistent
multiversal The multiverse is a Hypothesis, 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 Physical constant, consta ...
time required to make the evolutionary dynamics work, since short-lived universes with few descendants would then dominate long-lived universes with many descendants. Smolin responded to these criticisms in ''Life of the Cosmos'' and later scientific papers. When Smolin published the theory in 1992, he proposed as a prediction of his theory that no neutron star should exist with a mass of more than 1.6 times the mass of the sun. Later this figure was raised to two solar masses following more precise modeling of neutron star interiors by nuclear astrophysicists. If a more massive neutron star was ever observed, it would show that our universe's natural laws were not tuned for maximal black hole production, because the mass of the strange quark could be retuned to lower the mass threshold for production of a black hole. A 1.97-solar-mass pulsar was discovered in 2010. In 2019, neutron star
PSR J0740+6620 PSR may refer to: Organizations * Pacific School of Religion, Berkeley, California, US * Palestinian Center for Policy and Survey Research * Physicians for Social Responsibility, US ;Political parties: * Revolutionary Socialist Party (Portugal) ( ...
was discovered with a solar-mass of 2.08 ±.07. In 1992 Smolin also predicted that inflation, if true, must only be in its simplest form, governed by a single field and parameter. This idea was further studied by Nikodem Poplawski.


See also

* Black hole cosmology * Biocosm *
Anthropic principle The anthropic principle, also known as the "observation selection effect", is the hypothesis, first proposed in 1957 by Robert Dicke, that there is a restrictive lower bound on how statistically probable our observations of the universe are, beca ...
*
Quantum gravity Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics; it deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the vi ...
* General relativity * Quantum mechanics * Lee Smolin *
Fine-tuned universe The characterization of the universe as finely tuned suggests that the occurrence of life in the universe is very sensitive to the values of certain fundamental physical constants and that the observed values are, for some reason, improbable. If ...


References

{{reflist


External links


Cosmological Natural Selection
mdash; Underscores the coincidence of the constants being tuned for biological life as well as for black holes. Challenges the notion of "coincidence" in this context.
Scientific Alternatives to the Anthropic PrincipleCosmic natural selection
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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 ...
's criticism of this idea Physical cosmology