What Anthropic Reasoning Can Really Tell Us

February 8, 2008 By Lisa Zyga feature
What Anthropic Reasoning Can Really Tell Us
An infrared image of NGC 2244, an open cluster consisting of thousands of stars located in the Rosette Nebula. Stars can form thanks to our universe’s specific parameters, and create the heavy elements that are required for life as we know it to form. Image credit: SIRT/NASA.

Anthropic reasoning is under debate in the scientific community, and is considered by some as a cop-out. It has now lost further ground as physicists show that anthropic conclusions mostly reflect our biases rather than our knowledge.

Anthropic reasoning uses the fact that the universe seems fine-tuned to support life as we know it in order to explain various physical phenomena that are otherwise unexplained. And why is the universe fine-tuned to support life like us? Because, if it were otherwise, we wouldn't be here to observe it.

Case Western Reserve University physicists Irit Maor, Lawrence Krauss, and Glenn Starkman find this explanation troubling. As they write in a recent issue of Physical Review Letters, the anthropic principle is "based fundamentally on ignorance rather than knowledge." So they have tested the robustness of the anthropic explanation, stripping it down to its simplest scientific elements in order to determine what it truly can tell us about the universe we live in.

“In our work, we have tried to point out the hidden assumptions of anthropic reasoning: in a sense, you need to assume what you are trying to prove,” the three scientists told PhysOrg.com. “Moreover, we have provided a quantitative understanding of this issue.”

Importantly, anthropic reasoning implies that intelligent life requires the precise conditions found in our universe. For example, one of these conditions is the dominant contribution of something that acts like a cosmological constant (CC) to the energy density of the universe. Scientists have observed the CC to be not too large or too small that the universe would collapse or rip apart, but about right to allow matter to form galaxies and planets – a habitat for Earthly life. The anthropic explanation usually claims that life could not exist in a universe with other conditions, and therefore we would not be able to observe a different universe. However, the claim that life could not exist in a different universe is based on the assumption that we are a typical life form.

Maor, Krauss, and Starkman quantify how strongly anthropic arguments rely on the assumption that we are a typical life form. The researchers define a parameter space (a mathematically quantified collection) made of all possible universes with different CCs, and then try to determine a probability for life (either as we know it, or as we don't know it) within this collection. The problem here, they explain, is that we don't know what we can't observe, which leads to a sampling bias.

"As we are the only life-form and this is the only Universe we know, we have no information whatsoever about how Life extends over the rest of the parameter space," the researchers explain in their study. "It might spread over a wide range, implying life can take many forms, or it might require exactly the parameter values which lead to our life-form. . . . However, our limited data set of a single sample of a single point does not probe much of parameter space."

They come to the conclusion that, without the assumption of typicality, the connection between the value of the CC and the existence of life cannot be established, and therefore the existence of life cannot explain the CC’s special value.

"We can say that our existence is a good indicator of the observed CC," they conclude, emphasizing that correlation is far from causation. "The correlations illuminated by our limited anthropic understanding imply that what we ultimately learn from these arguments is that the existence of us and the existence of the observed value of the CC do not contradict each other. That is nice, but hardly surprising."

Unfortunately, the Case researchers and others still have more work to do before anthropic reasoning can successfully be dismissed as an explanation for why the all the parameters of our universe are such that it can support life.

“This debate is a complex one, and is not likely to be settled quickly because it is quite interdisciplinary,” the researchers explain. “It involves questions about the philosophy and methodology behind science, as well as questions about the actual observations and the mathematics used to analyze them. Moreover, as we state in the paper, the controversy stems, in large part, from our ignorance. We will need to learn more about the universe, and the fundamental laws governing it, before we can truly address some of these issues in an unambiguous way.”

Still, there is no guarantee that a fundamental explanation for these questions even exists. This may be one “why?” that can’t be answered in a definitive manner.

“Fundamental physics may or may not provide an explanation of the particular values of our universe's life-supporting parameters,” the researchers explain. “We may discover that the question ‘why is the mass of the proton 2000 times the mass of the electron?’ (which is essential for our exact form of life) is more like ‘why is the radius of Jupiter's orbit around the sun 5 times the radius of Earth's?’ than like ‘why does water expand when frozen?’ – a matter of probability rather than fundamental.

“However, we shouldn't assume that no explanation exists just because we don't yet know one, and, consequently, we should keep looking for an explanation at least until we have a convincing scientific theory that explains many other things and within which one can show that it is impossible to provide an explanation. The most interesting thing is that – unless we do discover a theory of everything – we will not know what is left to discover, which makes the search exciting.”

More information: Maor, Irit, Krauss, Lawrence, and Starkman, Glenn. "Anthropic Arguments and the Cosmological Constant, with and without the Assumption of Typicality," Physical Review Letters 100, 041301 (2008).

Copyright 2008 PhysOrg.com.
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.

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2.8 / 5 (4) Feb 08, 2008
Isn't this the biggest non-argument on the planet? These two statments are both true at the same time:-

1) If the parameters of a universe are set randomly then it would appear to be an enormous coincidence that the universe has parameters which are just right for life and the reason for this is worth further investigation.

2) There is no coincidence at all that when we look out at the universe we find that it can support life.

So what's the argument about?
1.7 / 5 (3) Feb 08, 2008
TimESimmons, I absolutely agree and am just as perplexed as you are.
2.3 / 5 (3) Feb 08, 2008
Most likely the fundamental underlying argument has more to do with religious v. naturalistic views of the world than the actual argument presented here. I am not sure why the article is particularly worthy of putting on PhysOrg - it is neither new nor unique - unless it is simply meant to stir up debate.
1.3 / 5 (4) Feb 08, 2008
Krauss is turning out to be quite a physics hack. First his infamous appeal to the Pope, and now this.

If they bothered to study the physics honestly, without the inclusion of an overdose of anticentrist dogma, then they'd find that the the observed universe has parameters which are just right for life only over a very specifically defined region of the observed universe and the reason for this predictive feature is most definitely worth further investigation.
2.8 / 5 (4) Feb 08, 2008
this has nothing to do with hard science, this is a philosophical debate. leave it off physorg.
1 / 5 (3) Feb 08, 2008
Krauss is self promoting again, by trying to stir up a pointless debate. If he succeeds to do this, he may then discredit his opponents are as the product of a substandard educational
system. You know, the science gap etc etc. To cure this, give him money.
1.7 / 5 (3) Feb 08, 2008
this smacks of unscience, but it's entertaining unscience none the less.
1 / 5 (3) Feb 08, 2008
The anthropic theorists are affected by the Heisenberg uncertainty principle and they extrapolate that intelligent observers were somehow necessary for the universe to form and that there is some connection between the future and the beginning of time that forms a feedback loop where the emergence of intelligent life in the present era enabled observation of the universe and that that present state somehow caused the the big bang to start everything. But what is intelligence and what is observation? Are amoebas or euglenas "conscious enough" to be termed observers of the universe if they sense light and darkness and move toward prey? All of the discussion of life forms on other planets and the vast differences they may have from human beings and DNA based life forms relates to answering the hypothesis "Is intelligent life necessary for the universe to have been created?"
Are electrons conscious of the force fields of protons and positrons when they move toward them, are they "sensing" those electric fields? Could that be called a quantum of observation or of consciousness, what minimum amount of observing is necessary to cause a big bang?
1.3 / 5 (3) Feb 08, 2008
Neil Farbstein said:
" " The anthropic theorists are affected by the Heisenberg uncertainty principle and they extrapolate that intelligent observers were somehow necessary for the universe to form and that there is some connection between the future " "

No, what "affects" the kind of theorist that you speak of, (like Paul Davies and John Wheeler), is the unavoidable fact that the anthropic coincidences are observed to be uniquely related to the structuring of the universe in a way that defies the most natural expectation for the evolution of the universe in a manner that is also highly-pointed toward the production of carbon based life at a specific time in its history, (and over an equally specific, fine-layer or region of the goldilocks zone of the observed universe). If you disallow unproven and speculative cutting-edge physics theories, then an evidentially supported implication does necessarily exist that carbon-based life is somehow "specially" relevant to the structure mechanism of the universe, and weak, multiverse interpretations do not supercede this fact, unless a multiverse is proven to be more than cutting-edge theoretical speculation.

Krauss, et.al., are only interested in discrediting the anthropic landscape of string theory, which is an entirely different bunch of non-science.

Neil Farbstein continued:
" " ...and that there is some connection between the future and the beginning of time that forms a feedback loop where the emergence of intelligent life in the present era enabled observation of the universe and that that present state somehow caused the the big bang to start everything. " "

The point that you and most everyone else always miss or ignore is that there is a natural expectation for a structure principle that would explain from first principles why the forces are configured the way that they are, rather than some other way, ("which would make the landscape go away"-David Gross).

"They" say that this is 'the biggest faiure of science in the last twenty years'... but not one of them except for Paul Davies is willing to recognize the kind of mechanism that's actually indicated by the observation that John Wheeler asked Brandon Carter to speak about.

So think about that real hard the next time that you hear someone say that they don't get what's so significant about the AP, because nobody will ever resolve the mystery of the missing structure principle if they are willfully ignorant of available DATA, not dogma.

1.6 / 5 (5) Feb 09, 2008
This is a poorly written article and ignores many ideas in physics. The fine scale constant may change with time. Superstring theory points to many possible universes. Dimensionless constants dont mean much. Read John Barrow's book on The Constants.
1 / 5 (2) Feb 09, 2008
Krauss has a point only if one is simultaneously asserting that our universe is the only one possible because we happen to be in it. But is not the multiverse concept based on numerous universes, some of which might have different parameters and 'life as we do not know it'? Not my field, but interesting speculation.

I thought the article was at least as appropriate as some of the advocacy material that finds its way into here from time to time.
1 / 5 (2) Feb 09, 2008
This isn't the only article/topic that shouldn't be given currency here.
1 / 5 (2) Feb 09, 2008


Chapter III

The Cosmic Drive and Purpose
The Drive and Purpose Of Life

(1) Again, Earth Life Is A Real Virtual Affair; it pops in and out of existence from its matrix, which is the energy constrained in Earth's biosphere. The totality of life in Earth's biosphere (the outermost part of the planet's shell %u2014 including air, land, surface rocks and water %u2014 within which life occurs, and which biotic processes in turn alter or transform. Wikipedia.) is a temporary grand store of constrained energy, and all living organisms are elaborate temporary energy storage containers and all base genetic materials are "Life quanta", carriers of "Life photons".

(2) Singularity and D-Infinity (max expansion/ cosmic energy dilution) are the two cosmic stable states. Their in-between is a metastable state, which is an everyday commonsense observation, like the observation that the denser the compacting goal of material the more energy is required, and vice versa the more thorough the disintegration of material the higher the amount of energy released. It seems that E=mC^2 is a specific case of the cosmic (and universal) process

E=Total[m(1 D)]

where D is the Distance from Big Bang point and the sum is of all spatial values of D from D=0 to D=selected value.

[BTW, (Nov 9 2006), following Newton (1) gravity is decreased when mass is decreased and (2) acceleration of a body is given by dividing the force acting upon it by its mass. By plain common sense the combination of those two 'laws' may explain the accelerating cosmic expansion of galaxy clusters, based on the above E/ m/ D suggested relationship.]

(3) Since the Universe, including its sub-systems, also Life, is a continuously evolving fractal system, ergo energy is the base element of everything and individual genes are the base elements of Life. Cosmic evolution is evolution of energy, and within it Life's evolution is the evolution of the genes/energy-quanta carriers.

At the beginning was the energy singularity. At the end will be near zero mass and an infinite dispersion of the beginning energy. In-between, the universe undergoes continuous evolution, consisting of myriad energy-to-energy and energy-to-mass-to-energy transformations. The cosmos evolution process comprises, though, phenomena of forms of temporary energy storage pockets, energy dispersion constraints. Examples of such temporary pockets are black holes of all sizes, and all forms of biospheres if/wherever they are.

The temporary constrained energy pockets are far-removed versions, up-fractionally evolved, scattered cosmic fragmants of singularity-akin energy sources. Energy stored in the temporary constrained energy pockets resists dispersion; we do not yet comprehend why and how. However, we comprehend that we, all Earth life, are real virtual products formed by Earth's biosphere energy for maintaining Earth's biosphere bio as long as possible.

end chapter III,

Dov Henis
1 / 5 (3) Feb 09, 2008
Our view of reality will remain always biased by antropocentric way, because the small part of chaos cannot see/describe the rest without biasing the white noise towards Gaussian noise, thus adding some causality into it.

For example, we will always see the Universe inertial, because without inertia we shouldn't observe it. From this perspective the Aether Wave Theory follows.
1 / 5 (1) Feb 09, 2008
Well I think we nailed that one.
1 / 5 (1) Feb 09, 2008
"Well I think we nailed that one."

To the cross!? I sure hope it doesn't come back again in the form of creationism 3.0, which is synonymous with armagedon!
not rated yet Feb 09, 2008
Well I think we nailed that one.

The post ratings say it all.
1.7 / 5 (3) Feb 10, 2008
Isn't it conceivable that our consciousness model as manifested in our perceiving minds precludes our ability to find a satisfactory answer to the "why of all why's." We can't answer this metaquestion because it exceeds our inherent limitations of design: three-dimensional and causality-biased; we just weren't equipped by the forces of chance and necessity that created us to be able to adequately answer this sort of ultimate question other than by way of myths and legends as found in various cosmogonies.
1 / 5 (1) Feb 10, 2008
Even if a question can never have an answer im pretty sure that therell always still be people trying to provide one!
You've got to remember (unless your a creationist) that we currently believe in evolution etc... in which life adapts to the environment-therefore conditions do not need to be perfect for humans (and so on) but only for the formation of a basis which evolves into whatever the suroundings will allow
not rated yet Feb 11, 2008
That's just not right. His claims that the A.P. means that no other universe could support life is going way to far. See http://en.wikiped...rinciple for commonly held variations.
The wikipedia article is far more reasoned than this article!
1 / 5 (1) Feb 11, 2008
It's may not be that The Universe only exists when obeserved but it may be that what is observed may be necessary to cause intelligence to exist. I am therefore I think.
1 / 5 (1) Feb 14, 2008
tomphys, ...minor point of fact: One can believe in creation ("creationism?") and still believe in evolution.
In the extreme case, evolution is the logical consequence of believing that God wants us to have "free will". Let me give you an minimalist example.
Some believe: a) "God is Almighty", b) "God wants our love, freely given, not forced (thus reason for "free will"). If these two beliefs are elements of your faith, it is logical to conclude that God would create a Universe that perfectly hides His existence from Science. To do otherwise would be to eliminate our freedom to believe or not, and hence our freedom to resist/deny His/Her power over us, and hence to truly "love" God rather than grovel like slaves at His/Her feet.
Science's current model of the Universe, traceable through eons of evolution all the way back to a singularity (i.e. "The Big Bang") fits this model nicely since it allows the "ultimate" creation, i.e. one from which all this flows from a single point in time with no further "tinkering" by God.
Following this argument, one can conclude that the existence of God cannot logically be proven or denied by science... else God is either not Almighty or did not intend us to have free will. This neatly wraps a bow around the whole mess, allowing non-believers and believers to coexist without any possibility of clashing over what "science" or "religion" can "prove".
It is thus illogical to argue that either Science or Religion can prove/disprove the existence of God. We can continue to explore the rich ideas of parallel universes, time travel, etc. suggested by the most far-out theories of science, but we need not waste our time thinking that we can prove/disprove the existence of God. The existence of God, BY DEFINITION, is a matter of Faith, not Science.

(One can, returning to the article, argue that "belief" itself, is anthropic, and thus both science and religion are anthropic. In science, we often come to "believe" we have enough data of sufficient resolution to provide evidence supporting our theories... often finding over time we were wrong! To "believe" is human, to "be", Divine!)
not rated yet Feb 15, 2008

1. Humans are supposed to be created in gods own image-if you believe in evolution and god at which stage in evolution did we resemble gods image?
2. At what point in our evolution did god start wanting the free willed love of humans? When we were microbes, primates?

Science-in particular physics looks to come to answers that we know ARE right and even if they become proved wrong it will be a success in refining our knowledge.

Also if the universe were fine tuned so that everything is predefined thne there is no free will anyway. If the universe was not so fine tuned that free will could exist then the effects of chaos would make everything totally unpredicatable............
1 / 5 (1) Mar 28, 2008
This paper is the perfect nullity: nothing about nothing.
1 / 5 (1) Mar 28, 2008

What is Life?
-Every organism, with its unique cognitive abilities, has a distinct perception of the universe; a singular, subjective reality.
-By the laws of reproduction and death, natural selection yields organisms with increasing cognizance of the universe, and so, through evolving lifeforms, life garners awareness and consciousness unfolds.
-Every living being is a shot at perceiving, conceiving the cosmos.
-Brain and body (central (brain and spinal cord) and peripheral (body) nervous systems) are the instrument by which consciousness/mind/spirit takes form and perceives the cosmos.
-There is no objective reality; all reality is subjective; there are numerous realities. What we call objectivity is nothing more than the intersubjective agreement of the species, the operational plane of reality of the lifeform.
-If there is no objective reality, no existence outside experience, perception is creation.
-The phenomenon of Life is the Will to Awareness; the cosmos conceiving itself.
1 / 5 (1) Sep 19, 2008
tomphys responded:
"1. Humans are supposed to be created in gods own image-if you believe in evolution and god at which stage in evolution did we resemble gods image?"

The only way we are 'created in God's own image' is in the ability to exercise free will (i.e. make decisions and thus (on the scale of shaping ourselves) 'create'.

tomphys goes on:
"2. At what point in our evolution did god start wanting the free willed love of humans? When we were microbes, primates?"

If God exists, time is no less limiting than distance. If a scientist in a lab mixes two chemicals with the intension of producing the final results of the reaction, the fact that intermediate reactions took place along the way does not disprove the intention.

tomphys: "Science-in particular physics looks to come to answers that we know ARE right and even if they become proved wrong it will be a success in refining our knowledge."

I agee completely, so long as we treat these words with customary sloppyness: "...answers we know ARE right and even if they are proven wrong..." would be better written "...answers we belive ARE right and even if ..."

tomphys: "Also if the universe were fine tuned so that everything is predefined thne there is no free will anyway. If the universe was not so fine tuned that free will could exist then the effects of chaos would make everything totally unpredicatable............"

Scientists and Preachers both make mistakes. The "predestination" taught by some religions IS (at least at the level of language) incompatible with "free will". Gedanken experiment: someone sets up a social experiment to see what people would do when presented with certain situations; the results are video taped; after the fact, the researcher knows definitively what each test subject chose to do in each situation. Does that mean the subjects had NO freedom of choice when the test was run? Of course not. Many misinterpret (often for their own purposes) the idea of a Being existing outside the limitations of time.

My observations are this: IF, as many believe, that "free will" exists and is a key attribute of the universe we live in, THEN neither science or religion can PROVE the existence of a supreme being EITHER WAY. BOTH scientists and preachers who claim they can PROVE the hypothesis either way fall into a logic trap: if an almighty being wants us to have free will, certainly that being would not create a world in which will would be destroyed by proofs either way.

Now you are certainly free to believe that free will does not exist or merely an accident of the uncertainty principle, but you are not, logically, able to PROVE those who choose to believe otherwise are wrong, either scientifically or religiously.

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