The anthropic principle:
a definition and critique
Version date: 4/8/2008
This text is an extract from the book
"Determinism Extended
to Better Understand and
Anticipate
A Bridge between Science and Philosophy"
http://www.danielmartin.eu/Philo/Determinism.htm
where the reader can find more details.
What is the
anthropic principle?
Physicists
noticed disturbing coincidences between values of constants of the Universe and
the possibility of life on Earth [242]. Here are two coincidences only among many,
such as the mass of the proton and the universal gravitational constant G:
§
The British astronomer Fred Hoyle noticed that if the nuclear
interaction [18] was only slightly different, carbon generation in
stellar reactions (the only source of carbon in the Universe) would have
been reduced to almost noting. Since carbon is indispensable to the life forms
we know, it seems that the nuclear force is "just right" for life to
appear in the Universe.
For
people who believe in the anthropic principle, the only possible explanation of this coincidence, and all the others
that were discovered, is the influence of a divine will.
§
The physicist and Nobel laureate Steven Weinberg stated in his book [145] that there is a relationship between the
cosmological constant [146] and existence of life on Earth.
A slightly greater value of this constant would have prevented galaxy
formation, therefore also the formation of the Solar system. Its known value is
compatible with the Universe's observed distribution of matter and its expansion, and a slightly
different value would have prevented life from appearing.
There
are so many such coincidences, and they are so disturbing, that physicists such
as Robert Dicke postulated the existence of an anthropic principle, according to which they are not due to chance.
This principle asserts that these
constants have exactly the right values for life to appear and evolve toward
complexity without requiring Darwin's natural selection. The Universe
behaves as if an external teleological will made it as it is, allowing life to
appear and evolve toward complexity until man appeared as we know him today.
The anthropic principle is, therefore, a modern form of the
teleological argument for God's existence described in Part 1 of the book.
Discussion
Is
the anthropic principle a divine determinism?
Since the above coincidences are real, each man may interpret them as he wishes, for example by postulating the existence, at the scale of the Universe, of determinism at a level above all the others. That "most global" determinism would govern the determinism of the various laws of physics like the principle of least action of Maupertuis [62] determines globally the choice of a trajectory that the local determinism of Newton's laws of motion determines at each point. It is also possible to interpret such a most global determinism as an effect of a Creator's will.
Let us not forget the principle of identity
One of the fundamental principles of logic
is the principle of identity [16], which affirms that at a given
time reality is what it is and cannot be different, even if we find it
astonishing, regrettable or full of coincidences. Given that principle, let us
consider the various constants of the Universe such that if one had a slightly
different value man couldn't exist. Since he exists, it is
impossible to find a fact that contradicts that existence; if one is found,
there must be an error! There is not a single constant or a single
law of physics associated with the possibility of man's existence which could
have been different, or the principle of identity would be violated. Being
astonished that a constant has a value very near a limit that would make life
impossible is psychologically understandable, but the astonishment proves
nothing for the constant cannot have any other value than the exact value it
has.
Meaningless
probabilities
Another
false argument in favor of the anthropic principle uses a probability for a constant of the Universe important for man's
existence of having (or not having) the precise value it has.
The
probability of an outcome being the ratio of the number of favorable outcomes
to the number of equally likely possible outcomes, it may only be calculated
knowing the latter. For example, the probability that a dice throw produces a 3
is computable, since this favorable outcome is one of 6 equally likely possible
outcomes. For example, such a probability is calculated in quantum mechanics
when the value of a measured variable is an eigenvalue of a set that has a
known, constant, number of eigenvalues.
When the
variable is a real number, the number of possible outcomes may be infinite. The
probability of a given value is then meaningless, because it is 1 favorable
outcome among an infinite number of possible outcomes. In that case, the only
possibility is considering a probability
density in its vicinity; without that density, the concept of "small
difference between a variable and a critical value" is meaningless.
Unfortunately, I have never seen a supporter of the anthropic principle
(surprised by the smallness of the difference between a variable value and a
value critical for life's existence) calculate the probability density in their
vicinity; and I have never seen it because the probability function being
unknown (assuming there is such a function) he couldn't have calculated it.
I have
seen, however, the argument that "a real variable's value is contingent,
because it could have had another value". This is pure speculation
precisely because the variable does not
have a value other than the one it has. In general, any calculation of the
probability of occurring of a situation
that occurred but is considered contingent is absurd because it is
impossible to know or to enumerate all conditions which caused it to occur, and
all conditions which would have prevented it from occurring.
Man
wants the Universe to make sense and conform to his moral values
The
anthropic principle has often been invoked by spiritualists who reject the
materialistic idea that man is a product of the Universe, which is dominated by
forces that are blind and indifferent. They cannot accept this materialistic
view because it doesn't allow them to
justify the origin of moral values, an origin which can only be divine in their
view because such values are by essence universal and eternal, in
conformance with the teaching of Saint Thomas Aquinas.
Materialists
respond to this objection that today
scientists have ethnological evidence that the principles of human ethics are
deterministic consequences of the evolution of human societies that defined
them progressively through the ages [154].
They criticize spiritualists:
§
For inventing the concept of a sacred God in order to attribute to Him
without justification the principles of ethics they consider so important and
they want enforced;
§
For not explaining why God also created barbarians such as Hitler, Pol
Pot and Bin Laden, whose ethics are obviously far from what the sacred texts
recommend; is it an error on His part, a lack of power, a punishment for
mankind, or what?
Origin
of man's superiority over other living beings
Darwin
responded to spiritualists in [42] page 428. He attributed the nobility of
the human lineage to its oldness, to the thousands of centuries of perfecting
that enabled it to survive natural selection. For him, man's ethics,
inseparable from his thinking, is a consequence of his social nature. It
constitutes one of the superiorities of his species, one of the reasons why it
survived and ended up dominating the others. He writes:
"When I view all beings not as special creations, but as the lineal descendants of some few beings which lived long before the first bed of the Cambrian system was deposited, they seem to me to become ennobled. […] And as natural selection works solely by and for the good of each being, all corporeal and mental endowments will tend to progress towards perfection."
An unfalsifiable principle
The anthropic principle is like God's
existence, it can't be falsified [203]. Following critical rationalism, it is not scientific. It’s a
spiritualists' amazement, or a product of imagination. It is always possible to
speculate that, in another Universe where laws would be different man would not
have appeared, but this is pure metaphysical speculation and no scientific
progress will ever enable us to know; we will never know any scientific fact about
a hypothetical space outside our Universe.
Conclusion
The
anthropic principle is spiritualist speculation that introduces divine determinism
to combat materialistic determinism.
References and
complements
[242] Anthropic principle - For
details, see:
§ "Cosmic Jackpot: Why Our Universe Is Just Right for Life" par Paul Davies, physicist and cosmologist, published by Houghton Mifflin (Boston, USA) in April 2007.
§ "Mind of God: The Scientific Basis for a Rational World" par Paul Davies, published by Touchstone (New York, USA) in March
1993.
§ Carl Sagan's TV series "Cosmos".
[18] Interactions (also termed forces) of the standard model
There are 4 types of forces. Each force corresponds to a field and its action is mediated by the exchange of interaction quanta:
§ Gravitation acts between all particles that have mass. Its interaction quantum is hypothetical because it has not been observed yet. Gravitation has an infinite range, acting even at astronomical distances, and its intensity decreases as the square of the distance.
§ Electromagnetism acts between electric charges. Its interaction is mediated by the exchange of photons. Its range is also infinite and its intensity decreases as the square of the distance.
§ Nuclear interaction (strong nuclear force) exerts an attraction between the quarks of an atom nucleus to maintain its cohesion as protons or neutrons. The corresponding interaction quantum is the gluon. Its range is very small (about 1 fm = 10‑15 m, one-tenth the size of an atom's nucleus) but its intensity increases with distance.
§ Weak nuclear force acts between particles called fermions (electrons, neutrinos, quarks and their antiparticles). Its action is mediated by quanta called bosons W and Z. Its range is extremely small, about 2 10‑18 m.
It is important to remember that every interaction between two particles exchanges an integer number of interaction quanta, so that its intensity is a discrete quantity.
[145] "Dreams of a Final Theory: The Scientist's Search for the Ultimate Laws of Nature" by Steven Weinberg (Pantheon Books, 1992)
[146] Cosmological constant: a constant introduced by Einstein in his equations of General Relativity to take into account a negative gravitational force able to compensate the attraction due to matter. Depending on the value attributed to this constant, the Universe can continue its current expansion, or this expansion may one day reverse itself and be followed by a Big Crunch.
[62] Principle of least action of Maupertuis – Definition of an action
When a body moves along a curve C following a path from point A (at time t1) to point B (at time t2) its action AC is the product of energy by time defined by:
where:
§ q1, q2, q3 are the coordinates of the body, functions of time t;
§ q'1, q'2, q'3 are the components of the body's velocity, time derivatives of q1, q2, q3;
§ L(q1, q2, q3 ; q'1, q'2, q'3 ; t) is the Lagrangian function of the body, defined as the difference between its kinetic energy and its potential energy.
The principle of least action (a provable theorem) states that among all possible trajectories between A and C the one chosen by nature is the one such that its action AC is minimal. It has been shown that this principle is equivalent to Newton's laws of motion, except that it replaces their step-by-step determination of the trajectory between A and B by a global determination.
The existence of this principle
and others shows that determinism can also, occasionally, exhibit a global behavior where the
intermediate situations are determined by the initial situation
("forgotten" by local determinism as soon as it is left) and the final situation which has not been
reached yet!
[16] The principle of identity asserts that a thing is identical to itself, and no different. If at this time I want something, that's what I want and nothing else; to want something else I would have to be different than what I am, which is logically impossible since I can't be described two different ways at the same time. At a given time, a man cannot want anything but what he wants.
More generally, at a given time, the Universe is what it is, with its physical laws and the precise value of each one of its constants; it can't be different. Any consideration of a situation at this time different from what it is, is pure speculation, as is examining the possibility for a past situation to have been different from what it was.
[154] Book by Michael Shermer "The Science of Good and Evil - Why People Cheat, Gossip, Care, Share, and Follow the Golden Rule" (Times Books, 2004).
Another article quotes research results that confirm the assertions of book above:
"Is ‘Do Unto Others’ Written Into Our Genes?" - The New York Times of 09/18/2007, http://www.nytimes.com/2007/09/18/science/18mora.html?th=&emc=th&pagewanted=print
[42] Charles Darwin "The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life." 6th edition, 1872
http://darwin-online.org.uk/content/frameset?itemID=F391&viewtype=text&pageseq=1
[203] An argument, a hypothesis
or a statement is termed falsifiable
if it can be disproved, for example by an experiment that proves it wrong or
inaccurate at least in one case. To be falsifiable, an argument does not
require a proof – it may be speculative or undecidable - but it requires a
wording such that it may be contradicted by a fact. The opposite of falsifiable
is unfalsifiable.
Examples
·
Ohm's law ("In electricity, the
current through a resistor is directly proportional to the potential difference
between its two ends") is falsifiable.
·
The statement: "This forest
fire is an act of God" is unfalsifiable.