Anthropic principle

The anthropic principle (from the Greek ἄνθρωπος ánthrōpos, «human») is a principle that is usually stated as follows:

In cosmology, the anthropic principle establishes that any valid theory about the universe must be consistent with the existence of the human being. In other words: "If in the Universe certain conditions must be verified for our existence, these conditions are verified since we exist." The different attempts to apply this principle to the development of scientific explanations about the cosmology of the Universe have led to considerable controversy.

Stephen W. Hawking, in his book History of Time, talks about the anthropic principle applied to the subject of the origin and formation of the universe. Hawking says, "We see the universe the way it is because we exist." He states that there are two versions of the anthropic principle: the weak and the strong. On the subject of the formation of the universe, he concludes by saying that if it were not as it is (or if it had not evolved as it did) we would not exist and that, therefore, asking how it is that we exist (or why not, &# 34;we don't exist") doesn't make sense.

The Cosmological Anthropic Principle is also the title of a controversial book by John D. Barrow and Frank J. Tipler published in 1986 in which the strongest version of the anthropic principle is exposed, which would imply the forced appearance of intelligent life as a cosmological consequence of the evolution of the Universe. The reasoning of Barrow and Tipler is, for many scientists, however, a purely tautological reasoning.

Indeed, the anthropic principle in its most basic form can be considered almost a commonplace, since it indicates that any theory about the nature of the universe must allow our existence as human beings and biological entities based on carbon at this particular time and place in the universe.

Origin

The first use of the term anthropic principle is attributed to theoretical physicist Brandon Carter. The first to deal with the idea in detail was Robert H. Dicke and it was later developed by B. Carter who in 1973, during a symposium celebrating the 500th anniversary of the birth of Copernicus in Krakow and which dealt with «The confrontation of cosmological theories with experimental data", he coined it to argue that, after all, humanity does have a special place in the Universe. (See: Copernican Principle) Thus, in his talk on "The Myriad Coincidences and the Anthropic Principle in Cosmology", Carter states that: "Although our position is not necessarily central, it is inevitably privileged in a sense." He proposed two versions of the anthropic principle:

• weak antropic principle

• Strong antropic principle

However, as mentioned, the basic idea of the principle had already been used before that year on several occasions. For example, in 1957 R. H. Dicke wrote the following: "The 'current' age of the of the Universe is not accidental but is conditioned by various biological factors... [the changes in the values of the fundamental constants of Physics] should conclude with the existence of a human who considers the problem». (R.H. Dicke, The Equivalence Principle and Weak Interactions, Rev. Mod. Phys. 29, 355 (1957)). And even in previous authors, formulations equivalent to this principle can already be found in texts such as Man's place in the Universe by Alfred Russel Wallace, published in 1903 where the following can be read: «A Universe as vast and complex as the one we know to be around us, it may be absolutely necessary... to produce a world so adapted to the development of a life that was to culminate in the appearance of the human being.' (p. 256-7 in the 1912 edition).

Proponents and versions

Proponents of the anthropic principle suggest that we live in a carefully tuned universe—that is, a universe that appears to have been meticulously tuned to allow for the existence of life as we know it. If any of the basic physical constants had been different, then life as we know it would not have been possible. In this sense, various articles have been written indicating that this principle could explain the need for various physical constants such as the fine structure constant, the number of dimensions of the Universe and the cosmological constant. As an example we can cite that if there were no light stars like the sun and, for example, all the stars were three times heavier, they would only live about 500 million years and multicellular life would not have had time to develop. If the rate of expansion of the universe one second after the Big Bang had been only one hundred billionth of a smaller, the universe would have collapsed again in a Big Crunch, if electrons had been faster and protons would not have come to form atoms. And other similar facts can be cited.

There are three main versions of the anthropic principle that were categorized in 1986 by physicists Barrow and Tipler as follows:

• The weak antropic principle (WAP) indicates that "the observed values of all physical and cosmological quantities are not equally likely, but are restricted by the fact that there are places in the Universe where it has been possible to develop carbon-based life and the fact that the Universe is old enough for this to happen."
• The strong antropic principle (SAP) indicates that "the Universe must have some properties that allow life to develop at some stage of its history."
• The end atropic principle (FAP) indicates that "an intelligent information processing mode must become in the Universe and, once it appears, it will never disappear."

The weak version of the principle has been criticized for its lack of imagination, since it assumes that other forms of life cannot possibly exist (which is why it has been branded by some as carbon chauvinism). It is also often said that the range of values that physical constants can take and that allow for the evolution of carbon-based life may be much less restricted than has been proposed (Stenger in 'Timeless Reality'). On the other hand, the strong version has been branded as unscientific, since it cannot be proven or falsified and is unnecessary. The third of the versions, the final version, is discussed in another article; although Barrow and Tipler indicate that, despite being proposed in the context of physics, the statement is "closely related to moral values."

Some of the philosophers of science who support the claims of the anthropic principle invite the conjecture of intelligent design. But, there are also those who suggest the existence of alternative universes and invoke the anthropic principle to help their theories: assuming that some universes among all the possible ones were capable of harboring intelligent life, some of the concrete universes must have made this capacity a reality, and ours is clearly one of them. However, alternatives to the Intelligent Design Conjecture are not limited to proposing the existence of alternate universes. Others, however, understand that the anthropic principle as it is normally stated in reality undermines the arguments of the intelligent design conjecture.

Another modern version makes use of Chaos Theory, proposing that the configuration of the universe, in all its details and at any scale, is a sine qua non condition for the occurrence of events that would produce a specific planet, with a specific composition and size, located in a specific orbital area, around a star with specific characteristics, in a solar system with a specific configuration, located in a specific area of a specific galaxy, in a specific region of the universe; and all this so that the human phenomenon could be produced.

The simplest version is the one that simply stipulates that we perceive the universe as we do because it is the only way we can perceive it, that is, our perception of the universe depends on our installation in it and our relationship with it.

The cosmological anthropic principle

In 1986 the controversial book The Anthropic Cosmological Principle, written by John D. Barrow and Frank J. Tipler, was published by Oxford University Press. In this book Barrow, the famous London cosmologist, then at the University of Sussex, made an academic foray into what he called the anthropic principle and which purported to explain the seemingly incredible series of coincidences that allow for our presence. in a universe that seems to have been perfectly prepared to guarantee our existence. Everything that exists, from the specific energy constants of the electron to the precise level of the strong nuclear force, seems to have been precisely adjusted for our existence and the existence of other living things. The existence of carbon-based life in this Universe is supported by several independent variables; and if any of these independent variables had a slightly different value, carbon-based life could not exist. Thus, the anthropic principle implies that our ability to study cosmology implies in any case that all variables have the correct value. In the words of early critics, a tautology that says 'if things were different they would be different'.

Although Brandon Carter presented his ideas in 1974 in an International Astronomical Union publication, in 1983 he stated that, in its original form, the principle was only intended to alert astrophysicists and cosmologists to possible errors that would result. of the interpretation of astronomical and cosmological data unless the biological constraints of the observer were taken into account. In 1983 he also warned that the opposite could be true for evolutionary biologists and that in interpreting the evolutionary record, one must take into account the astrophysical constraints on the process. With this in mind, Carter came to the conclusion that the evolutionary chain could probably only include one or two links of little evolutionary success in the available time interval. These claims were discussed by A. Feoli and S. Rampone in 1999 in an article titled "Is the strong anthropic principle too weak?" arguing that the estimated size of our universe and the estimated number of existing planets allow greater degrees of freedom for evolution and allow us to conclude that there is no evidence of intelligent design in the mechanism of evolution.

In the late 1990s there was a renewed interest among scientists motivated by experimental cosmology and theoretical work on quantum gravity. The theoretical works involved the attempt to unify gravity with the other physical forces. Although there were a significant number of promising developments, they all seemed to suffer from the same problem: the fundamental constants of physics seemed to have no restrictions. The experimental reason came from cosmological observations that offered very specific values for some fundamental quantities, such as the density of matter in the Universe; Contrary to what was expected, the value was not zero, but 0.7 (a value that can by no means be considered obvious).

However, more recent publications (2004) by the famous British physicist Stephen Hawking suggest the idea that our Universe is much less 'special' than it is. than the proponents of the anthropic principle intend. According to Hawking, the probability that a universe like ours arises from a Big Bang is 98% and, furthermore, using the basic wave function of the Universe as a basis for his equations, Hawking has concluded that such a Universe can come into existence without that there is any relationship with anything prior to it, that is to say that it could arise from nothing. In any case, at present, these publications and the theories that accompany them are still the subject of scientific debate, and that in the past, Hawking himself had asked himself questions that seem to point to basic questions of the anthropic principle: «What is what breathes fire into the equations and makes them describe a Universe?... Why does the Universe bother to exist?» (Hawking, 1988).

Anthropic bias and anthropogenic reasoning

In 2002, Nick Bostrom asked, "Is it possible to summarize the essence of the observation selection effect with a simple statement?" to which he concluded that perhaps he could, but that "many of the "anthropic principles" they just get confused. Some, especially those who drew their inspiration from Brandon Carter's seminal papers, are strong, but... too weak for any real scientific work. In particular, it is believed that the current methodology does not allow any observational consequences to be derived from contemporary cosmological theories despite the fact that these theories can be and are being extensively tested experimentally by astronomers. What is needed to fill this methodological gap is a more adequate formulation of how the selection effects of observations are accounted for." Thus he assumes that self-sampling systems are those in which "you can think of yourself as a random observer of a suitable reference class." This expands into a model of anthropic bias and anthropic reasoning under the uncertainty introduced by not knowing our place in the Universe - or even who we are. This may also be a way to overcome the various limits of cognitive bias inherent in humans making observations and sharing models of the Universe using mathematics.