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The Anthropic Principle

It has recently been realised that if some of the fundamental physical constants of the universe were only slightly different then the existence of life in this universe would have been impossible. As John Wheeler said: "It is not only that man is adapted to the universe, the universe is adapted to man. Imagine a universe in which one or another of the fundamental dimensionless constants of physics is altered by a few percent one way or another. Man could never come into being in such a universe." Is this apparent "fine-tuning" of the cosmos evidence of a Creator, or is there another explanation?

For example, The worst problem of fine-tuning in physics is the cosmological constant problem. The cosmological constant is the "pressure" of the physical vacuum, which controls the expansion of empty space. If the cosmological constant was much larger then the universe would have expanded so fast that no galaxies could have formed. Alternatively, if it was much smaller then the universe would have collapsed too quickly for our life to form. As Stephen Hawking asked: "Why is the universe so close to the dividing line between collapsing again and expanding indefinitely? In order to be as close as we are now, the rate of expansion early on had to be chosen fantastically accurately."

As another example, why are there three dimensions of space, rather than one or two, or a hundred? It has been known for more than a century that stable planetary orbits would be impossible to achieve in any different number of dimensions.

These remarkable coincidences extend to particle physics. The Standard Model of particle physics has 19 undetermined parameters, some of which must be fine-tuned to an accuracy of one percent to make an inhabitable universe. Similarly, changing the strength of any of the four fundamental forces - even by a small amount - would appear to render life impossible. There are many, many more of these fortuitous coincidences, and Martin Rees lists many of them on his Just Six Numbers website.

If you have heard the recent pronouncements of various physicists (such as Stephen Hawking) you might get the impression that the issue of apparent anthropic fine-tuning has been settled and is no longer a problem for physics. But this is far from the truth. In fact, not only is there currently no convincing solution to the problem, but most of the proposed solutions seem far-fetched and fundamentally unscientific. The fine-tuning question remains a huge problem for physics.

Several explanations have been proposed: Is there some necessity for life to exist - sentient intelligent life which could observe and ponder the universe - or else the universe could not come into being? Can the conditions for life be set less rigidly? Is there a multiplicity of universes with the constants set differently in each universe? (For a survey of all these explanations, see the section "Issues of Ultimate Causation" at the bottom of George Ellis's website The Universe around Us).

But perhaps the most famous (infamous?) interpretation of the Anthropic Principle is that we are we living in a "designer universe" (considered by Steven Weinberg here).

Critics of the Anthropic Principle dismiss such thinking by saying that human life exists in its current form purely as a result of the nature of this particular universe. If the constants were set differently then life might well not exist and we would not be around to ponder these questions. As Steven Weinberg says: "To conclude that the constants of nature have been fine-tuned by a benevolent designer would be like saying, 'Isn't it wonderful that God put us here on earth, where there's water and air and the surface gravity and temperature are so comfortable, rather than some horrid place, like Mercury or Pluto?' Where else in the solar system other than on earth could we have evolved?"

Other critics would also say that carbon-based life is not the only possible type of life: maybe an entirely different form of silicon-based life would exist, for example, if the physical constants were set differently. However, from the list of coincidences (and the particular example of the precise setting of the cosmological constant, considered here), it would appear that the majority of values which the constant could take would result in no life ever being possible, the universe either spreading too far too quickly, or else collapsing back on itself. According to the proposer of string theory Leonard Susskind: "The notorious cosmological constant is not quite zero, as it was thought to be. This is a cataclysm and the only way that we know how to make any sense of it is through the reviled and despised Anthropic Principle." (see here).

Recent discussion of the Anthropic Principle has moved away from the "designer universe" type of interpretation towards a so-called "multiverse" interpretation. This rehabilitation has seen the Anthropic Principle come in from the cold from being perceived as a slightly cranky theory on the periphery of science towards playing a central role in the latest interpretations of string theory and cosmology.

The multiverse interpretation suggests that there are a vast number of different universes (infinitely many?), the collection of universes being commonly referred-to as the multiverse. The physical constants are set to different random values in each universe. This arrangement would require no fine-tuning: we just happen to be inhabitants of a universe in which the physical constants are suitable for life.

(Max Tegmark has published a comprehensive survey of all the varied multiverse theories - see here).

The Landscape

According to string theory, elementary particles are actually one-dimensional objects: small vibrating strings. For the equations of string theory to be mathematically consistent, a string has to vibrate in 10 dimensions, which implies that six extra dimensions exist but are curled-up too small to be detected. The laws of physics in this universe would depend on the geometry of those hidden dimensions.

But the solution to the equations is not unique as so many different geometries are possible in these extra dimensions. The bundle of curled-up extra dimensions can have many different shapes (topologies), such as a sphere, a doughnut, two doughnuts joined together, and so on. The vast collection of solutions differ in that each configuration has a potential energy associated with it called the vacuum energy (basically, Einstein's cosmological constant), the energy of the spacetime when the four large dimensions are completely devoid of matter and fields.

Each solution to the equations could be taken as representing a universe with different physical constants and laws of physics. We could represent each of the 10500 possible solutions as an abstract mathematical graph, plotting the vacuum energy against the geometrical parameters. The geometry of the small dimensions would try to adjust to minimise the vacuum energy, just as a ball placed on a slope will roll downhill to a lower position. As the physical constants and laws of physics in our universe do not appear to be changing with time, we must be sitting at a minimum in the bottom of a valley. In particular, we seem to sitting at a minimum with a slightly positive vacuum energy.

Leonard Susskind has called this mathematical space The Landscape (see his Edge article or his paper The Anthropic Landscape of String Theory).

The Landscape

In a fascinating discussion between Leonard Susskind and Lee Smolin (see this Edge article), Smolin has no time for this "giving up on the maths" Anthropic Principle of the Landscape and suggests a Cosmological Natural Selection (CNS) process instead. According to CNS, baby universes are produced on the other side of black holes. The attraction of CNS is that the values of the physical constants might appear out of the maths as the optimal value of some kind of "fitness" measurement. The most successful universes will have most stars and black holes, and will therefore have conditions amenable to life (stars producing the heavier elements necessary for life such as carbon and oxygen). We will be considering this proposal further down the page in the section on "Darwinian evolution of the universe".

Eternal Inflation

Leonard Susskind suggests the Landscape structure could arise within an eternally inflating universe, the structure of which was proposed by Andrei Linde in his paper Inflation, Quantum Cosmology, and the Anthropic Principle.

It is now widely believed that the expansion of the universe in the first moments of its existence was driven by a scalar field (also known as the inflaton field), a mysterious energy field powering the expansion of the universe. If the behaviour of the potential energy density of the scalar field is modelled then it is found that the field was slow to react to the universe's expansion ("slow-rolling down a potential energy hill" - see here), resulting in an energy density exponentially higher than would be expected. As a result, the universe experienced a period of extraordinarily rapid expansion called inflation.

Random quantum fluctuations in the scalar field, , continue to occur due to the Heisenberg Uncertainty Principle:

If the quantum fluctuations are large enough then this can result in areas of secondary inflation (a process known as nucleation). This process can continue indefinitely. Hence, in an eternally inflating universe, "bubble" universes can bubble-up out of an eternally inflating space like bubbles in a bottle of champagne.

Due to random quantum fluctuations at the moment of creation of each bubble universe the values of the physical constants can vary: the masses of the elementary particles, the strength of gravity, even the mathematical forms of the laws of physics including the number of dimensions of space! As a result, some of the bubbles do not expand, and some shrink back down to zero size. Our visible universe would be contained in one of the expanding bubbles.

All of the possible combinations - each of these bubble universes - is represented by a different point on the Landscape.

(This eternally inflating universe introduces a slight confusion of terminology: The entire structure containing all the bubbles is frequently referred to as the "universe", though my personal preference is to understand each bubble as a separate universe with the entire structure containing all the bubble universes being referred to as the "multiverse". This is in agreement with the semantic definition contained here. This is the terminology I use throughout this article.)

A Problem in the Multiverse?

Not everyone is a fan of the multiverse. One implication of the multiverse interpretation of the Anthropic Principle is that we no longer have to seek to find an elegant mathematical explanation of why the fundamental constants are set to their unique values. We only have to postulate the existence of a random process whose task is to which sets the constants to different random values in each universe - job done! This apparent side-stepping of difficult questions for which we currently have no answer is not welcomed by all. Brian Greene from "The Elegant Universe": "The Anthropic Principle has the capacity to lessen our insistence on explaining why our universe appears as it does". This echoes the concerns of Lee Smolin (discussed above).

Other critics of the multiverse have referred to the writings of the philosopher Karl Popper who believed that a theory had to be falsifiable or else it could not be considered a part of science. In his book of various essays, Are Universes Thicker Than Blackberries?, Martin Gardner delivers a scathing criticism of multiverse theories, quoting Popper: "Science does not proceed by induction - that is, finding confirming instances of a conjecture - but rather by falsifying bold, risky conjectures. Confirmation can be slow and is never certain. By contrast, a falsification can be sudden and definitive. Moreover, it lies at the heart of the scientific method." As the multiverse is stated to lie beyond the causal horizon of our universe, multiverse theories can never be proved wrong, and as such they should not be considered scientific.

I think it's fair to say that Paul Steinhardt is not a fan either: "I think it is far too early to be so desperate. This is a dangerous idea that I am simply unwilling to contemplate." (see here).

The Requirement for a Selection Process

One of the attractions of multiverse theories is that they appear to explain how the universe we inhabit takes the form it does. Why are the masses of the elementary particles set to their particular values? Why are there three spatial dimensions? It might appear that there has been some sort of selection process at some stage (not to be confused with a selection effect), selecting these values from a list of possible values. However, multiverse theories would appear to avoid any such requirement for a selection process: it is only in our particular universe that the physical constants are set to these values - in another universe they would all be set to different values. Thus multiverse theories appear to solve the selection problem.

However, there is something illusory about this neat solution. The selection problem has not been solved, in fact it has only been pushed back to a deeper, more fundamental layer.

At the core of why this problem arises is the principle that, while some features vary between each universe in a multiverse structure giving each universe its different characteristics, there must always be some invariant features that do not vary at all with each universe in a multiverse structure. These are the unchanging features which are necessary to generate each universe, including providing the underlying substrate of the entire multiverse structure. And it is these invariant features which now apparently require selection (rather than the features in the higher layer) - the selection process has just been pushed back to a deeper layer.

Paul Davies refers to this problem in his recently-published comprehensive study of the Anthropic Principle "The Goldilocks Enigma". He refers to the invariant features as the "universe-generating laws": "In the standard multiverse theory, the universe-generating laws are just accepted as given: they don't come out of the multiverse theory."

As an example, the theory of eternal inflation (described in a box above) is a wonderfully neat and imaginative multiverse solution which can give an impression of being an entirely self-contained theory as to why the universe takes the form is does: random quantum fluctuations cause inflation of "bubble universes", and those same random quantum fluctuations result in each bubble universe having different characteristics. It's all very neat, giving an impression of "having all the answers". However, the driving force behind eternal inflation - the constant feature in each bubble universe - is that random quantum fluctuation process governed by the Heisenberg Uncertainty Principle (the bubble universes being created by quantum nucleation). And that leads to the question: "Why does the quantum randomisation process take the form is does? Might it not have been a non-random process instead? What selection process sets the Planck constant in the Heisenberg relation?" Or, to put it another way, "How come the quantum?", asked John Wheeler. Eternal inflation also assumes the presence of the underlying spacetime substrate (possessing 10 or 11 dimensions) - another invariant feature - spreading through each universe. Eternal inflation gives an impression of answering our questions about the selection process in the universe, but that is illusory - the requirement for a selection process has just been pushed back to a deeper, more fundamental layer.

This principle was obviously realised by the New Scientist interviewer in this discussion with Leonard Susskind: "So even if you accept the multiverse and the idea that certain local physical laws are anthropically determined, you still need a unique mega-theory to describe the whole multiverse? Surely it just pushes the question back?" (see here). Paul Davies also refers to the problem in "The Goldilocks Enigma": "Like the proverbial bump in the carpet, the popular multiverse models merely shift the problem elsewhere - up a level from universe to multiverse."

It is always possible to consider a deeper level than the multiverse and say "Why is this particular multiverse structure selected (over other possible multiverse structures)?" Do we now have to consider multiverses in which the invariant features of the substrate (Paul Davies's "universe-generating laws") can vary, take other forms, or not exist at all?! If so, then this would point to there being some requirement for a multiverse selection process!

So maybe we have to take a further step back ...

And now ... the Ultiverse!

If we are now considering the invariant features of the multiverse substrate we are now posed with the question: "Why does the multiverse have its particular universe-generating laws and substrate structure? Why this multiverse rather than some other multiverse with a different structure?" To get round this new multiverse selection problem maybe we have to take a step backwards to a deeper layer and start considering a multiverse of multiverses, with the underlying structure being different in each multiverse.

But now we seem to be in an infinite regression. Do we have to consider multiverses of multiverses of multiverses of multiverses? There seems to be no way to avoid the selection process, it just keeps getting pushed further and further back.

So how do we avoid this selection problem? Maybe the answer is to keep stepping backward until we consider the most fundamental level of all, and then presume this is completely unconstrained: the "ultimate multiverse" (or ultiverse, to coin a phrase). Just say "Absolutely anything can and will happen". That would appear to be a way to avoid the selection problem: avoid making any selection at all!

This "anything goes" ultiverse structure was first proposed in 1986 by David Lewis in book The Plurality of Worlds. He suggested that every logically consistent universe actually existed (see modal realism).

Andrei Linde has also considered this unconstrained situation: "In some countries, everything that is not explicitly allowed, is forbidden. In some other countries (and in science), everything that is not explicitly forbidden, is allowed. We live in one of such countries, so why don't we use the freedom if it does not make us any harm?" (see here). He goes on to say: "In science, everything that is not explicitly forbidden, is allowed" (a view based on Murray Gell-Mann's Totalitarian Theorem: "In physics, anything that is not forbidden is compulsory."). (I shall challenge these views later).

John Barrow in his book Pi in the Sky had a similar idea when he considered that our universe could be imagined as a simulation running on computer hardware. As such, the type of computer hardware on which our "program" runs is irrelevant - we can be considered to be pure mathematical states, inhabitants of a mathematical "Platonic" realm (see the section "Simulated Universe and Substrate-Independence" on the Mathematical Universe page for a full discussion of this). According to John Barrow: "This approach has all sorts of interesting ramifications. It means that anything that can happen - anything that is a possible consistent statement in the language of mathematics - does happen in every possible sense of the word". This theme is taken to its logical extreme in the section "Max Tegmark's Mathematical Universe" on the Mathematical Universe page.

These previous references to "logically consistent universes" (Lewis) and "consistent statements" (Barrow) are crucial: if this proposed ultiverse is to successfully exist in physical reality then it must be logically self-consistent (physical reality can have no inconsistencies, no contradictions or paradoxes). But if the ultiverse is defined as the place where "absolutely anything can and will happen", will this necessarily give a logically consistent result? Surely not. In the page on The Mathematical Universe it was explained how physical reality could be considered as being built-up from a set of fundamental axioms: an axiomatic system. If the ultiverse is defined as the place where "absolutely anything can and will happen" then the resultant physical reality is being built-up from every possible axiom! Such a system could surely never be logically consistent: paradoxes would be rife. Any statement could be proved true (and false!) (to see how unrestricted axioms would lead to Russell's paradox - see here). In our completely unconstrained ultiverse we find ourselves having to postulate the existence of absolutely anything and everything. As an example of the problem in physical terms, our axiomatic system would have to include the existence of an object which destroys the entire ultiverse structure! Self-referential paradoxes render the whole ultiverse structure logically inconsistent. This criticism was also raised by Page in his paper Predictions and Tests of Multiverse Theories: "Different mathematical structures can be contradictory, and contradictory ones cannot co-exist. For example, one structure could assert that spacetime exists somewhere and another that it does not exist at all. However, these two structures cannot both describe reality."

(I notice that in Section VII of his latest paper, The Mathematical Universe, Max Tegmark considers the problem of these inconsistencies in his "anything goes" universe. He avoids the problem by imposing the restriction that the universe must be a computable structure - but that's hardly "anything goes". Tegmark concedes: "it may sound like a surrender of the philosophical high ground, effectively conceding that although all possible mathematical structures are 'out there', some have privileged status". For more on this, see the section "Mathematics with no practical application" on the Mathematical Universe page.)

So it would appear the ultiverse is a bit of a non-starter. We're back to square one.

It would appear that in the transition from unconstrained mathematics to physical reality there must be some "selection process" which chooses only certain logically consistent systems (from the full range of mathematical possibilities). In fact, that selection process could be considered the very definition of physical reality!

We also have to consider how this "selection process" selects only our particular universe from the range of possible universes, with the particular values we observe for the fundamental constants in our universe. This is not a problem for Max Tegmark and his varied parallel universes, or Andrei Linde: "In science, everything that is not explicitly forbidden, is allowed" (a view based on Murray Gell-Mann's Totalitarian Theorem: "In physics, anything that is not forbidden is compulsory."). However, I would contend that precisely the opposite is true: physical reality prohibits any multiple-valued property values appearing in the real world. The Totalitarian Theorem is based on the principle that quantum particles appear to possess multiple property values before observation. For example, in Feynman diagrams we have to consider a particle taking all possible paths to get from A to B. But - and it's a big "but" - when we observe the particle we only see it in one position, we only see it take one path. Multiple particle paths and multiple parallel universes are only a mathematical method, a calculational convenience, a means for obtaining the single result we see in physical reality. As Carl Brannen says: "In my own mind, the creation and annihilation operators, and the zero point energy and all that, are not parts of the physical world, but instead are just mathematical conveniences. I think that there is a strong tendency in the physics community to confuse mathematics with physical reality." - quoted from here. So not only do we have to discover how this selection process only selects logically consistent universes, we have to discover how the process selected our particular universe.

But what is the cause of this selection process? What is responsible for this "carving" of physical reality from all possibilities?

From Ultiverse ... To Nulltiverse!

We have just discussed the requirement for some sort of "carving" operation to define one particular logically consistent physical reality from the space of all possibilities. But what is supposed to be responsible for this selection operation? Perhaps a more attractive solution is if we do not consider a physical reality "carved" out of everything, but rather consider it to be "built-up" out of nothing. Instead of a situation in which absolutely everything exists without need of a reason, we would now have a situation in which absolutely nothing would exist without a good reason for its existence. Following in a long line of painfully-contrived names, we might call such a structure a nulltiverse.

So we now need to seek an ex nihilo (creation out of nothing) scenarios for the universe. But what could possibly spring into existence in such an empty nulltiverse structure? Well, only those objects which could create themselves could come into existence (I find this more palatable than the previously-discussed unconstrained creation "for no good reason" principles of the ultiverse). Hence there would be no need of any selection or "carving" process to identify physical reality: objects select themselves, springing out of nothingness. But what sort of objects can create themselves? And, most importantly, could our very universe have created itself?

"Darwinian" Evolution of the Universe

Many different proposals have been presented to explain the apparent "life-friendly" fine-tuning of the universe. One of the most intriguing recent ideas was that of cosmological natural selection, proposed by Lee Smolin.

Smolin suggested that when a universe forms a black hole, another "baby" universe is formed on the other side of the black hole. So universes can effectively give birth to new universes. Within the universe which is created, other black holes (and, hence, other universes) can emerge. The end result is a "family tree" of universes:

In a process which resembles Darwinian evolution, the most numerous and the most successful universes will be the ones which form the most black holes (hence, giving birth to the most "baby" universes). As black holes form when a star collapses, the most successful universe will therefore by those which contain the most stars. And stars are essential for forming the building block elements of life, such as carbon. So Smolin's proposal would appear to be an explanation of anthropic fine-tuning: why our "life-friendly" star-filled universe has emerged.

A variation of Smolin's theory, called the Meduso-Anthropic principle, was presented by Louis Crane and (independently) by Edward Harrison. Crane and Harrison realised how important the role of advanced intelligence will be in the future evolution of the universe. Future civilisations will be able to create black holes - and hence universes - within the laboratory. Some of those created universes would go on to develop advanced civilisations within themselves, and those civilisations would go on to create new universes. The most numerous universes would therefore be the ones more amenable to the production of intelligent life. Once again, there appears to be an explanation for the anthropic fine-tuning of our universe, and this time the solution involves the emergence of intelligence.

I'm impressed by the Meduso-Anthropic principle, mainly because it appreciates the importance of the role which intelligence will play in the future evolution of the universe. However, I feel the principle falls short in two key ways:

  1. The principle does not provide an reason as to why advanced civilisations would necessarily feel the need to create these "universes in a laboratory".
  2. The principle does not explain how the first universe - the root of the family tree - came to be created. This is the so-called problem of "First Cause".

However, on the Intelligent Universe page, a hypothesis will be presented which provides a solution to both these problems. We will see that the advanced civilisation will HAVE to create a universe if they want to exist, and in doing so they provide an explanation so the problem of the "first cause" is avoided: they create the universe which creates themselves!

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Another problem with "The Goldilocks Enigma" is Paul Davies naive assumption that there is such a thing as "Chance". Davies is not alone. We all begin by thinking we know what chance is. If a coin is tossed we believe that "chance" will determine whether it will fall heads or tails. But that is not really the case. To say that something is a chance event is really to say that all the causal factors of the event are not known to us. If we construct a machine to provide an identical impetus and angle to the toss of a coin it will fall predictably. Modern mass production frequently relies on this mechanistic predictability. We all know what Unicorns are, just as we all know what chance is. But neither really exists. Both Unicorns and Chance are just epistemological concepts, ideas that can exist in our minds. They are not ontological realities, entities that really exist.

Nicolai Hartmann has shown that "nothing in the world exists by chance in the ontic sense. Everything depends on conditions and occurs only where these are fulfilled. ("New Ways of Ontology" 1953, 70) Randomness is not synonymous with "chance". Other known planets are products of the same matter and forces as Earth, but they are all different from planet Earth. The processes that produced these planets are random in the sense that the intersection of a range of physical laws, in different particular material circumstances, gave rise to these different outcomes. Similarly we can observe the random nature of the number plates on vehicles on a highway, but we understand that different factual circumstances in each case gave rise to this apparent randomness. Randomness is not the result of “chance”.

My article "The Intelligent Design of the Cosmos" criticizing Martin Rees "Just Six Numbers", on the site apply also to The Goldilocks Enigma. - Dr. A.B. Kelly, 29th December 2006
Thanks for an interesting post, Anthony.

Referring to your statement "To say that something is a chance event is really to say that all the causal factors of the event are not known to us", it appears that quantum mechanics is fundamentally indeterminate, that it is not a result of our incomplete knowledge of the causal factors (see the page on the "Quantum Casino": ). I don't think you should assume there can be no such thing as fundamental indeterminacy in nature.

I think you're being a bit harsh on The Goldilocks Enigma. Paul Davies makes very few assumptions about "chance" or anything else for that matter. That is the strength of the book.

"Rees does not explain why a large number of universes would necessarily vary from one another." This refers to the in-built assumptions of the multiverse theories about the "invariant features" which I mentioned in my main article - Paul Davies's "universe-generating" laws - and the unexplained space-time substrate which you also refer to.

Neither Martin Rees's three possibilities or your own paper appear to consider the possibility of a universe which generates itself, setting its own parameters for life, something along the lines of John Wheeler's "participatory universe".

For interested readers, here's a link to Dr. Kelly's paper: - Andrew Thomas, 29th December 2006
Hi, I've studied the anthropic physics in some depth, so you might want to check-out my blog: Predictions that the Goldilocks Enigma makes about the observed universe: There is a form of pre-conceived prejudice, or "anticentrist dogma" (as Brandon Carter put it), that diverts scientists reactionarily away from any serious investigation into the first most apparent implications of the evidence that points toward a strong anthropic principle. Their first and only tendency is to find rationale to "explain away" evidence, rather than to give equal time to it, and that isn't science, it's politics. - island, 1st February 2007
"Resolving the Goldilocks Enigma" is on the website, paper No. 87: - Dr. A.B. Kelly, 13th March 2007
Andrew Thomas
Thank you for your comments. Sorry I was so long getting back to you. I took account of your comments in “Resolving the Goldilocks Enigma”.
You say:

”Referring to your statement "To say that something is a chance event is really to say that all the causal factors of the event are not known to us", the Copenhagen Interpretation says that quantum mechanics is fundamentally indeterminate, that it is not a result of our incomplete knowledge of the causal factors. I don't think you should assume there can be no such thing as fundamental indeterminacy in nature.”
We live in a stratified world, and each stratum e.g. (sub-atomic), (matter), (life), has its own categories. To apply concepts appropriate in one category to a different category of reality is what philosophers call a category mistake. Indeterminacy at the sub-atomic level cannot be applied in the world of matter where the Principle of sufficient reason applies, where everything is, and is as it is, for a reason.
For a universe to generate itself it would have to exist before it existed. Perhaps it is self-existent. If so it is God. Self-existence is the attribute of divinity.
You quote Steven Weinberg saying: "I have to admit that, even when physicists will have gone as far as they can go, when we have a final theory, we will not have a completely satisfying picture of the world, because we will still be left with the question 'why?' Why this theory, rather than some other theory?"

I address the Why question. My resolution makes sense of the evidence.

My papers are on my Web page at any comments welcome. - Tony Kelly, 3rd April 2007
Reading these fascinating studies and the posts, there seems to be one point that you touched on - in Veiled Reality - that may be the crux of the whole matter. You spoke of the underlying reality which we are unable to observe. Also, entanglement seems to contradict observed reality. Perhaps we are trapped in a "Veiled Reality" ourselves, and its the real world that we can't see. It seems that there is simple evidence of this, and that is, that we are trapped by the arrow of time. We cannot observe anything except what obeys the arrow of time. That this is a limited view of reality is evidenced by the behaviour of entangled particles. This takes us back to what was presented as long ago as St-Augustine, who said that it is pointless to consider what happened before Creation, because time, as a measure of before and after, was created along with everything else. If time is a dimension of the space-time fabric, then the question of "What caused the Big Bang?" is a meaningless question. At the same time, all the other universes disappear, because they are unnecessary - if there was no time - no before & after - before (or rather "outside") the moment the space-time continuum was created, then there was nowhere for them to be. Hard for us finite beings to comprehend, but not so hard if you view time as following the laws of a mathematical dimension. It raises many questions, such as causation, probability, etc., all of which are constrained by the arrow of time. - John, 4th June 2007
To me the subject is all absorbing but out of neccessity, I have to leave the factual science to those who can.
Reading through the above however and having delved a little into Carters reasons for postulation of the AP, I realise that without the labourious business of explaning them each and every time a dialogue errupts there will be an overwhelming number of disbelievers. It is fruitless and waste of time to try and knock The AP. To destroy it you would have to show why the majority of the real science "chances ?" can not be used as evidence. In any case, I believe Carter did not define the sentient life form as being specifically Humans only that had to be able to understand. - Igno, 11th January 2008
Hi there,

My name's Nildson Alvares Muniz.I'm a Brazilian anthropologist.Since 1996 I have dedicated myself to study Einstein's General theory from an anthropological perspective which means from a perceptual point of view.This idea I have been inspired by Gaston Bachelard and Maurice Merleau-Ponty's studies.Right now I'm writing to you from Brazil.Despite not being undergraduated/graduated in Physics my reasoning about the original and important contributions so far given by Brandon Carter and John Barrow to the anthropic cosmological principle might not be accomplished and reached if it is not given by a brand new anthropological thinking.
Despite being two good contributions to the study of Copernic Perfect Cosmological Principle, I must be sincere, their contributions are uncomplete to solve these open questions.The ideas developped by Professors Carter and Barrows are without doubt good contributions but I must say so far uncomplete. I would like to point out that my reasoning is, if we are to have a clear and complete contribution dealing with a perfect anthropic cosmological principle, we should take into consideration some other antropological aspects if we really want to understand any connection between the vastness of the Universe and the existence/explanation of human life on Earth. Just to mention one possibilitiy to have these enigmas solved or better explained if we really want it. A good contribution is to be found in the works of Merleau-Ponty. One should remind that the understanding of these questions related to cosmological principles are also related to the phenomenology of particles and phenomenology itself.Which means these cosmological problems and principles are in fact, biological and phenomenologic problems.My idea is one should have another scientifc model able to explain, for example, how the quantum mind related to the external world is able to relate the phenomenology of particles with human phenomenology. A brand new way of studing these questions and taking into consideration visual and sensorial perceptions. This new model is only possible if we do take into consideration a new reasoning about quantum mind structured with the perceptions of memory,imagery and the unconscious. This model was started and sketched presented in the model of the Phenomenology of Perception studies started by Maurice Merleau-Ponty in his work- The Phenomenology of Perception.In order to conclude my comments, I would like to emphasize that the answers to both works of Professor Carter and Professor Barrow are not to be found in the studies of cosmology itself.But on the relation of man to the cosmic landscape.

Sincerely yours,
Nildson alvares muniz - Nildson Alvares Muniz, 22nd March 2008
I love these discussions, but you have to call the subject matter what it is: philosophy, not science (not that there's anything wrong with that.) Does anyone have any idea how to verify or falsify these any of these ideas? - Stephen VandeCarr, 12th September 2008
Stephen, I know Lee Smolin gave a talk on how to test multiverse theories, but I haven't actually got round to watching it myself yet: - Andrew Thomas, 12th September 2008
Hi Andrew, I could not find a "general comments" section, so I am dropping this here.
Really simply laid out, well done, with great opening segments to a bunch of really deep topics.
Thanks Much! - Todd, 20th October 2008
Hi Todd, thanks so much for your support. It really encorages me to keep going. - Andrew Thomas, 20th October 2008
The apparent coincidence of physical properties in our universe may simply imply that the properties are mathematically correlated. Shouldn't this point the way to unified theory? - Kingstilts, 24th January 2009
Yes, I understand what you are suggesting: instead of a series of apparently independent coincidences we would then only need one coincidence and all the other values would be related to that.

Yes, you might have a good point there. I think it reveals how difficult it is to assign real values to these likelihood values for these coincidences - if there are any correlations in existence. Of course, at the moment we no of no such correlations, so this is beyond the current state of our knowledge. - Andrew Thomas, 26th January 2009
I'm sorry, but I don't think the Anthropic Universe is "Philosophy" at all. It can be, in fact it probably gives rise to more "Pop Philosphy" than any other part of Physics.

Let us not forget however, than in 1919 when The London Times virtually screamed Sir Arthur Eddington's confirmation of Einstein's General Relativity, that "Relativity" devolved into Pop Philosophy, to whit: "Everything is Relative," including Morality, which it is not. And yet, this is what happened.

Anthropic has a specific place in Physics, and an important one, and that is to define those exact initial conditions that gave rise to this Universe we live in.

It is very important not to overthink the concept, but no less worse to ignore it. Thank you, Andrew. - Steven Colyer, 20th March 2009
Andrew, I'm surprised the six numbers didn't include the fine structure constant, 1/137. Wolfgang Pauli and his pal Carl Jung explored its possible meaning. Ironically in one of his last hospital stays before his premature death, Pauli was a patient in Room 137. - Greg Sivco, 18th May 2009
Hi Greg, I think the key thing is that Martin Rees is only picking the constants whose values could not be altered or else all life would be impossible. Hence, he picks things which control the expansion of the universe, for example. Or if planets could not be formed then life would be impossible. It's not necessarily the case that life could not possibly exist with a different fine structure constant. - Andrew Thomas, 19th May 2009
Thank you, Andrew, I certainly understand Martin Rees' intent, my contention is that his list may not be complete. In my defense I offer up the following 2 sections from the Wikipedia article on "Fine-structure constant":

"The anthropic principle is a controversial explanation of why the fine-structure constant takes on the value it does: stable matter, and therefore life and intelligent beings, could not exist if its value were much different. For instance, were α; to change by 4%, stellar fusion would not produce carbon, so that carbon-based life would be impossible. If α; were > 0.1, stellar fusion would be impossible and no place in the universe would be warm enough for life.[29]

The fine structure constant plays a central role in John Barrow and Frank Tipler's broad-ranging discussion of astrophysics, cosmology, quantum physics, teleology, and the anthropic principle.[30]"

and ...

"'If alpha [the fine structure constant] were bigger than it really is, we should not be able to distinguish matter from ether [the vacuum, nothingness], and our task to disentangle the natural laws would be hopelessly difficult. The fact however that alpha has just its value 1/137 is certainly no chance but itself a law of nature. It is clear that the explanation of this number must be the central problem of natural philosophy.'
—Max Born, Arthur I. Miller (2009), Deciphering the Cosmic Number: The Strange Friendship of Wolfgang Pauli and Carl Jung, W.W. Norton & Co., p. 253, ISBN 9780393065329" - Greg Sivco, 22nd May 2009
Brilliant. Thanks a lot for that, Greg. - Andrew Thomas, 23rd May 2009
You're welcome Andrew, but I'm not quite sure how my ability to "copy and paste" equates to "brilliance." However if you do like said ability, here's more, and I find the following a tad spooky. From the same article:

"Attempts to find a mathematical basis for this dimensionless constant have continued up to the present time. For example, the mathematician James Gilson has suggested [1] that the fine-structure constant has the value:

\alpha = \frac{\cos \left(\pi/137 \right)}{137} \ \frac{\tan \left(\pi/(137 \cdot 29) \right)}{\pi/(137 \cdot 29)} \approx \frac{1}{137.0359997867} ,

29 and 137 being the 10th and 33rd prime numbers. The difference between the 2007 CODATA value for α; and this theoretical value is about 3 x 10-11, about 6 times the standard error for the measured value."

Now, that formula is actually quite simple (sorry we can't use the LaTex module for writing mathematical symbols here ... or can we?) in spite of its looking complicated when written in prose.

What is spooky is the presence of Prime numbers, 28 and 137, in the equation. A bit strange in that if SETI and others are to find "alien" civilizations, we and they seek out a pattern of Primes in the intra-stellar electromagnetic spectrum, as Primes are not supposed to occur naturally. Yet there you have it .. a "natural" equation based on Prime numbers. Not sure what to make of it, but I'm pretty sure what the DI crowd will. :-) - Greg Sivco, 25th May 2009