The Anthropic Principle

[Simplicius]

I've run into the anthropic principle in some of my casual reading, and I saw a new book in the library that purportedly connects it to string theory. It took me a while, but I think I understand the basic connection between the existence of life in the universe and the value of fundamental physical constants, although I'm not quite sure which way the principle states the relationship.

How controversial or accepted is the anthropic principle? The dust jacket of the book (sorry I can't remember title or author, but I can look it up later) made it sound controversial, while reading in an earlier book made the dispute seem much smaller.

Secondly, exactly which way around is it? Is it that life exists in the universe because the physical constants allow it to do so, or that the universe is as we see it because we exist to see it (or, to paraphrase the dust jacket, the existence of life is a precondition for the structure of the universe)? The first seems too much of a truism to be of much use, and the second sounds way too humanocentric to be good science.

[Beowulf]

The Anthropic Principle (in either weak or strong forms) is essentially a tautology. It is unfalsifable, unless we somehow managed to create, or visit, other universes.

[Sriad]

Douglas Adams, quote, puddle, hole.

[Simplicius]

Sounds about right.

Does anybody know why it even exists, or why it would rear its silly head outside something like creationism? It seems odd that it came up in books that were generally surveys of scientific understanding (Ferris's Whole Shebang is what I read; I assume it's not a terrible book).

[petesampras]

Sounds about right.

Does anybody know why it even exists, or why it would rear its silly head outside something like creationism? It seems odd that it came up in books that were generally surveys of scientific understanding (Ferris's Whole Shebang is what I read; I assume it's not a terrible book).

I don't think creationists ever use the anthropic principle.

It simply states for any universe where questions are asked about the nature of the universe, said universe must conform to certain standards for it to be possible for those questions to be asked. Don't see what's silly about that, seems a pretty sensible statement.

[mr friendly guy]

Reading through my book "Why Intelligent Design Fails" edited by Matt Young and Taner Edis (definitions copied straight from the book)

Basically there is the Weak anthropic principle (WAP) which is defined as the observed values of all physical and cosmological quantities are not equally probably but take on values restricted by the requirement that there exist sites where carbon based life can evolve and by the requirement that the universe be old enough for it to have already done so.

There is also the strong anthropic principle (SAP) which states that the universe must have those properties which allow life to develop within it at some stage in its history.

There is another one called the Final anthropic principle (FAP) : intelligent information - processing must come into evidence in the universe, and once it comes into existence it will never die out. This was also ridiculed as the Completely ridiculous anthjropic principle (CRAP).

Basically they assume because these physical constants allow life (as we know it) to exists, therefore it must have been designed that way by an intelligent designer for the purpose of creating life. Never mind Occam's Razor which would suggest life arose because of such conditions.

Its a circular argument, ie life needed certain physical constants, therefore the universe has these constants so that life can arise. Thats like saying because humans need the earth, therefore the earth was created for humans. The implicit assumption in this is that only life as we know it will exist, as opposed to completely different life if the constants were different.

Also note that ID adherents argue that evolution (ie natures laws) don't allow life to develop, therefore they needed the help of an intelligent designer. Yet the same people would use the "fine tuning" argument and state that nature is such that it allows life to develop, therefore a supernatural explanation must have done it. Obviously the concept of double talk and logical consistency doesn't occur to them.

[Ariphaos]

Its a circular argument, ie life needed certain physical constants, therefore the universe has these constants so that life can arise. Thats like saying because humans need the earth, therefore the earth was created for humans. The implicit assumption in this is that only life as we know it will exist, as opposed to completely different life if the constants were different.

It's more appropriate in the context of a multiverse or an eternally altering Universe, where there are any number of possibilities but we observe our Universe now because we are actually capable of doing so, while there are an unknown number of universes or times (could be zero, could be infinite) where life such as ours cannot exist.

[petesampras]

Reading through my book "Why Intelligent Design Fails" edited by Matt Young and Taner Edis (definitions copied straight from the book)

Basically there is the Weak anthropic principle (WAP) which is defined as the observed values of all physical and cosmological quantities are not equally probably but take on values restricted by the requirement that there exist sites where carbon based life can evolve and by the requirement that the universe be old enough for it to have already done so.

There is also the strong anthropic principle (SAP) which states that the universe must have those properties which allow life to develop within it at some stage in its history.

There is another one called the Final anthropic principle (FAP) : intelligent information - processing must come into evidence in the universe, and once it comes into existence it will never die out. This was also ridiculed as the Completely ridiculous anthjropic principle (CRAP).

Basically they assume because these physical constants allow life (as we know it) to exists, therefore it must have been designed that way by an intelligent designer for the purpose of creating life. Never mind Occam's Razor which would suggest life arose because of such conditions.

Its a circular argument, ie life needed certain physical constants, therefore the universe has these constants so that life can arise. Thats like saying because humans need the earth, therefore the earth was created for humans. The implicit assumption in this is that only life as we know it will exist, as opposed to completely different life if the constants were different.

Also note that ID adherents argue that evolution (ie natures laws) don't allow life to develop, therefore they needed the help of an intelligent designer. Yet the same people would use the "fine tuning" argument and state that nature is such that it allows life to develop, therefore a supernatural explanation must have done it. Obviously the concept of double talk and logical consistency doesn't occur to them.

Hmm. I didn't think that the anthropic said the universe had to support life, just that in order for science to exist there must be intelligent life, thus whenever scientific questions are asked it must be in a universe that is capable of supporting intelligent life.

[Rye]

The anthropic principle is reducable to "if things were different, things would be different," only in more verbose language that for no reason other than to sound less vacuous, applies itself to human development. The idea goes that the universe had to be finely tuned to give us what we see today, humanity included.

This is true to an extent, but this doesn't have any real significance. It's tautological; if there is an outcome, the preceding conditions must be capable of producing that outcome.

Does that mean the preceding conditions were intelligently, artificially crafted, or necessarily could even be any different? Does it mean, it's impossible that in some other set of constants, similar phenomena couldn't arise in approximately equal niches? Does it bollocks. It doesn't even imply that the outcome is intended. Is there any evidence that humans were the intended product of the natural universe, and not a fuckton of hydrogen? How about rocks? The lithic principle.

And yes, as I've pointed out before, and mr friendly guy pointed out, the anthropic principle is often used by IDeist creationists on the one hand to say that the universe is designed, but then at other times, they say that abiogenesis/evolution need helping hands, both positions undermine one another. But then, they say that God can make it any way he wanted, at which point, you can say that you cannot, therefore determine any deital design from anything, because there's nothing that cannot be rationalised under "he can make it any way he wants."

[petesampras]

Does that mean the preceding conditions were intelligently, artificially crafted, or necessarily could even be any different? Does it mean, it's impossible that in some other set of constants, similar phenomena couldn't arise in approximately equal niches? Does it bollocks. It doesn't even imply that the outcome is intended. Is there any evidence that humans were the intended product of the natural universe, and not a fuckton of hydrogen? How about rocks? The lithic principle.

No, but it does mean that the answer to the question 'can the universe support intelligent life' is always 'yes'. I still don't see how it links in at all to creationism.

A similar issue comes with determining the general properties of planets in the universe. Using your homeworld as an example of a planet can skew your models, because homeworlds MUST have certain properties.

I was discussing this with someone the other day, in terms of the likelihood of their being intelligent life elsewhere. He insisted that dividing the number of planets we know to have intelligent life (1), by the number of planets we know of in total( I think 50 or so?) was acceptable.

[petesampras]

I was discussing this with someone the other day, in terms of the likelihood of their being intelligent life elsewhere. He insisted that dividing the number of planets we know to have intelligent life (1), by the number of planets we know of in total( I think 50 or so?) was acceptable.

Acceptable to calculate the probabilty of any random planet developing intelligent life, that is. Which it isn't.

[drachefly]

To elucidate the connection to String Theory,

Certain kinds of String Theory suggest that different parts of the universe could have different 'compactifications', which boils down to having different rules.

In that case, the universe is sampling 'parameter space', which, roughly speaking, multiplies the probability that some part of it will be able to harbor life by the number of adequately-unrelated rule sets it contains.

One of the consequences of the anthropic principle is that there will be no extremely simple way of deriving the strengths of the forces and a variety of other constants of nature, for much the same reason that it is impossible to derive the Earth's mass, radius, orbital radius, orbital eccentricity, axial tilt, etc. from the rules of nature and nothing else.

If it turns out that we DO find a simple representation of the fundamental rules, constants included, then that strikes a very strong blow against this concept. If however, we end up with a theory which though in other ways is perfect, requires a bunch of parameters which have no apparent relationship to each other, that would support it.

And of course if String theory is correct and we can actually eventually find regions with different compactifications, then that would REALLY support it.

[Wyrm]

Its a circular argument, ie life needed certain physical constants, therefore the universe has these constants so that life can arise. Thats like saying because humans need the earth, therefore the earth was created for humans. The implicit assumption in this is that only life as we know it will exist, as opposed to completely different life if the constants were different.

The WAP is actually a rather straightforward argument under the assumption that the universe is naturalistic in operation, but it is Bayesian in nature. If the universe's constants were incompatible with (say) forming carbon, then carbon life could therefore not evolve. That we do see carbon life is (among other things) positive evidence that the universe contains carbon, and therefore, has constants compatible with forming carbon. In other words, the fact that we are here and are carbon based life puts restrictions on the posterior distribution of the constants of nature, and on the age of the universe. To put it another way, the constants and age of the universe being incompatible with carbon life implies that there should be no carbon life. Therefore (by contrapositivity) if we see carbon life in this universe, the constants and age of the universe are compatible (ie, not incompatible) with carbon life.

Now, I would call the CRAP and SAP non sequitors. It doesn't follow from the constants of the universe being compatible with life that the universe's purpose is to create that life, and then never allow it to die out. That's the CRAP. In the case of SAP, we have the same form as the simple argument of WAP, but makes it a foregone conclusion that the constants of the universe are actively restricted to these values.

[Zero]

I'd always thought that the anthropic principle merely states that since we exist, the universe must operate in such a way that allows us to exist. That can't really be debatable... it's only really the assertion that we're here. That being said, it's kind of a pointless principle. The universe must operate in such a way as to allow any observation we make possible. Theories are disproven by showing contradictory data. If there were a theory that didn't allow for carbon-based life forms to exist, then it would be shot down by the existance of the theorist.

It's a useless principle, even if it's correct.

[mr friendly guy]

Does that mean the preceding conditions were intelligently, artificially crafted, or necessarily could even be any different? Does it mean, it's impossible that in some other set of constants, similar phenomena couldn't arise in approximately equal niches? Does it bollocks. It doesn't even imply that the outcome is intended. Is there any evidence that humans were the intended product of the natural universe, and not a fuckton of hydrogen? How about rocks? The lithic principle.

No, but it does mean that the answer to the question 'can the universe support intelligent life' is always 'yes'. I still don't see how it links in at all to creationism.

By itself its just a tautology. However creationists try to use it to imply an intelligent designer. To do this they need the implicit assumption that God must have set these conditions to allow humans to exist and humans existed because God set these conditions.

[dworkin]

I always thought the universe existed so that I could play Alpha Centuri.

Of course this veiw is a bit silly considering I've lost my SMAC disk.

[Durandal]

The anthropic principle is basically a formalization of "Duh".

People often use it to conclude that the universe must have been "fine tuned" by some intelligent entity for us, which is a ridiculous conclusion to say the least. By the very nature of the anthropic principle, we would be unaware of any of the preceding trial universes. For all we know, our current universe could just be the latest in a series of trials, and this one just happened to generate intelligent life by random chance.

It's a basic display of human hubris. We assume that, because we exist, we're special and that there must have been special accommodations made for us. The reality is that we're a very tiny, insignificant spec on the universe's ass. It we annihilated ourselves tomorrow, the universe wouldn't lose sleep over it.

[Lord Zentei]

Observe that feet fit shoes nicely. Therefore, feet must have been designed with the intent that we wear shoes on them.

Observe how useful sand is in making concrete. And I happen to live in a fine house made of the stuff. Sand exists for our benefit.

Observe how useful gas is in powering automobiles. The only conclusion we can draw is that there is a purpose for all that oil in the ground, and that this purpose is to power automobiles.

[Keevan_Colton]

The anthropic principle is basically a formalization of "Duh".

People often use it to conclude that the universe must have been "fine tuned" by some intelligent entity for us, which is a ridiculous conclusion to say the least. By the very nature of the anthropic principle, we would be unaware of any of the preceding trial universes. For all we know, our current universe could just be the latest in a series of trials, and this one just happened to generate intelligent life by random chance.

It's a basic display of human hubris. We assume that, because we exist, we're special and that there must have been special accommodations made for us. The reality is that we're a very tiny, insignificant spec on the universe's ass. It we annihilated ourselves tomorrow, the universe wouldn't lose sleep over it.

Unless this is the only planet with life that requires sleep and we take it all with us...then the universe would lose sleep