Anthropic Principle: Opposition & Logic Explored

[1dominator1]

What is everyone's opposition to the anthropic Principle? Is it not an application of deductive logic at it's purest level? We exist, therefore we must exist in a universe that allows for our existence. Seems to make perfect sense, or am I missing something crucial?

 

[island]

What is everyone's opposition to the anthropic Principle? Is it not an application of deductive logic at it's purest level? We exist, therefore we must exist in a universe that allows for our existence. Seems to make perfect sense, or am I missing something crucial?

That is only one lame variant interpretation of it that is only applicable if there is a multiverse, (for which you need a complete theory of quantum gravity or a final theory to justify), or if you can produce a cosmological principle that explains from first principles why carbon based life is simply an accidental consequence of the otherwise completely unexpected and highly pointed configuration that is observed.

People don't like the interpretation that you are using because it is like throwing up your hands to first principles in order to rationalize via anthropic **selection** rather than from a true cosmological principle.

A true anthropic cosmological principle would explain the structure of the universe from bio-oriented first principles, which is actually what is *most apparently* being called for by the observation, and is often referred to as "the appearance of design*, as if there is intent, or more likely, a physical *need* for carbon based life to appear within a very specific time frame, and over an equally specific region of the observed universe, that somehow constrains the vacuum energy density to the extremely small and most unexpectedly low configuration that is observed in complete opposition to quantum theory, which naively says that the expected energy density is about a hundred and twenty orders of magnitude greater than we observe.

Out of the choices of chance, design and necessity, the latter is the most scientific, since it resolves the problem of the flat yet barely expanding universe from first physics principles, but few physicists, (or anybody else that isn't a creationist), are even willing to admit that the *appearance of design* exists, due to their own religious belief begrudgingly known to physicists as "Copernicanism", which causes people to willfully ignore and/or "explain away" evidence that indicates any kind of strong interpretation of the observation. Brandon Carter called this disease, "anticentrist dogma" because the rationale runs contrary to the evidence.

http://knol.google.com/k/the-anthropic-principle#

 

[Chalnoth]

What is everyone's opposition to the anthropic Principle? Is it not an application of deductive logic at it's purest level? We exist, therefore we must exist in a universe that allows for our existence. Seems to make perfect sense, or am I missing something crucial?

No, seems like you've got it right. The anthropic principle, when applied properly, is simply a selection effect. It must be taken into account when considering any sort of model for the birth of our observable universe. A multiverse isn't actually necessary, because the anthropic principle itself is a tautology, and is therefore undeniably true no matter what the underlying laws of nature actually are.

The complaints regarding this principle stem from a combination of lack of understanding and emotional dislike of the argument, perhaps mixed in with a few people using anthropic arguments communicating poorly.

 

[island]

No, seems like you've got it right. The anthropic principle, when applied properly, is simply a selection effect. It must be taken into account when considering any sort of model for the birth of our observable universe. A multiverse isn't actually necessary, because the anthropic principle itself is a tautology, and is therefore undeniably true no matter what the underlying laws of nature actually are.

The complaints regarding this principle stem from a combination of lack of understanding and emotional dislike of the argument, perhaps mixed in with a few people using anthropic arguments communicating poorly.

Nope, that's only one *weak* variant interpretation, not some hard stone written "proper application'. Either the universe must be the way that it is or it MUST be the way that it is. The first is a weak "selection effect" interpretation and it is NOT observed. The latter is the strong cosmological interpretation that is *most apparently* indicated by bio-oriented physics that has a directly observable commonality to the structure of the universe itself, so you must have a multiverse or a dynamical structure principle that explains why the observed bio-orientation is simply a consequence of this physics in order to justify the assumption that the interpretation is weak, in opposition to the observation.

Nice try, but you have to willfully ignore, deny, or rationalize away *observably apparent* "anthropic privilege" i.e., "the undeniable appearance of design", (as Leonard Susskind puts it), in order to say that it is still a selection effect without a multiverse.

I must say that as things stand now, if the "Landscape" fails, without any explanation of nature's fine tunings, we will be hardpressed to answer the IDists... the appearance of design is undeniable.
--Lenny

 

[Chalnoth]

Nope, that's only one *weak* variant interpretation, not some hard stone written "proper application'. Either the universe must be the way that it is or it MUST be the way that it is. The first is a weak "selection effect" interpretation and it is NOT observed.

Er, what are you going on about?

First of all, the original poster clearly didn't mean the strong anthropic principle, and neither does just about anybody in science. So I didn't see the relevance of splitting hairs over that distinction.

Nevertheless, the weak anthropic principle, "observers must observe that their existence is possible," doesn't need observational support, because it is true by the definition of the words used. It is trivial to prove this statement because the converse, observers observing their existence as impossible, is, well, impossible.

The latter is the strong cosmological interpretation that is *most apparently* indicated by bio-oriented physics that has a directly observable commonality to the structure of the universe itself, so you must have a multiverse or a dynamical structure principle that explains why the observed bio-orientation is simply a consequence of this physics in order to justify the assumption that the interpretation is weak, in opposition to the observation.

Nice try, but you have to willfully ignore, deny, or rationalize away *observably apparent* "anthropic privilege" i.e., "the undeniable appearance of design", (as Leonard Susskind puts it), in order to say that it is still a selection effect without a multiverse.

I have no idea what you are trying to say here.

 

[island]

I have no idea what you are trying to say here.

The complaints regarding this principle stem from a combination of lack of understanding and emotional dislike of the argument, perhaps mixed in with a few people using anthropic arguments communicating poorly.

Wrong, The reason people, (people, as in, anybody that matters), dislike the weak anthropic principle is because they see it as a tautological cop-out on first principles, and they are right. David Gross called 'science's inability to produce said dynamical principle that would make the landscape go away, the single biggest failure of science in 20 plus years', so learn the subject before you rant because you have well proven that you do not know what you are babbling about.

There is no weak anthropic principle without a multiverse or said cosmological principle, because there is no evidence that the weak interpretation can supercede the implications of the observation without a final or complete theory to justify it.

The observation is most apparently not weak, so the weak interpretation doesn't exist without many unjustified assumptions, period.

 

[Chalnoth]

Wrong, The reason people, (people, as in, anybody that matters), dislike the weak anthropic principle is because they see it as a tautological cop-out on first principles, and they are right.

Like I said, a failure to understand combined with an emotional dislike. Whether you like it or not, the weak anthropic principle is necessarily true. End of story.

That some people see the application of the weak anthropic principle as a cop-out is their problem.

David Gross called 'science's inability to produce said dynamical principle that would make the landscape go away the biggest failure of science in 20 plus years', so learn the subject before you rant because you have well proven that you do not know what you are babbling about.

The problem is that taking that sort of attitude requires an implicit reliance upon the strong anthropic principle: that the laws of the universe must be such that life is possible. He (and many other theorists, it is sad to say) have taken the unreasonable stance that the laws of physics of some GUT (e.g. string theory) must necessarily reduce to the low-energy laws of physics which we observe, and only those.

And making such an untenable assumption is just plain unfounded.

There is no weak anthropic principle without a multiverse or said cosmological principle, because there is no evidence that the weak interpretation can supercede the implications of the observation without a final or complete theory to justify it.

Sure there is. The weak anthropic principle makes no assumption whatsoever about the nature of the universe. It only says that whatever the universe is like, observers within that universe will only observe conditions where their existence is possible.

It's just that we are inexorably driven to the multiverse as more and more evidence mounts that the properties of the low-energy laws of physics are at least partially due to accidents in the past. It is positively disgusting that so many people still fight so strongly against the various multiverse ideas, just because they find them unpalatable.

 

[island]

The weak anthropic principle makes no assumption whatsoever about the nature of the universe.

Wrong, it ignores the strong implications of the observation, so it isn't valid without justification that nobody has, like I said.

 

[Andrew Mason]

The above discussion shows that the anthropic principle, however characterised, is not a principle of science. It is philosophy. There is nothing wrong with philosophy. It is often very important in driving the guesses of theoretical physicists. But, questions like: "are there other universes out there that we cannot interact with because our laws of physics do not apply in such universes?" are questions for philosophical debate. One can argue about the reasoning behind the existence or non-existence of multiple universes. But it is not a scientific argument. It is a philosophical debate - at least at this point.

So I suggest this thread be moved to the "PF Lounge>General Discussion>Philosophy" board.

AM

 

[marcus]

...
It's just that we are inexorably driven to the multiverse as more and more evidence mounts that the properties of the low-energy laws of physics are at least partially due to accidents in the past. It is positively disgusting that so many people still fight so strongly against the various multiverse ideas, just because they find them unpalatable.

.

Chalnoth, are you saying that "more and more evidence mounts" that a multiverse exists?

I realize that today's theoretical physics has some obvious shortcomings---things it fails to explain and future theoretical progress may explain. I don't see the present shortcomings of physics as evidence of the existence of something invisible. So what is this "mounting evidence" you are talking about?

And what do you mean by "accidents"? Do you mean permanently unexplainable? Human understanding is in its infancy--- just getting started--- our understanding is growing, as is our ability to explain.

I doubt very much that we are at some special point in history where our understanding meets an insuperable barrier of "more and more evidence" and stops growing.

 

[Chalnoth]

Wrong, it ignores the strong implications of the observation, so it isn't valid without justification that nobody has, like I said.

The only contingent statement in the weak anthropic principle is the existence of observers. We observe that we exist. That is all that is required for it to apply.

 

[Chalnoth]

.

Chalnoth, are you saying that "more and more evidence mounts" that a multiverse exists?

I realize that today's theoretical physics has some obvious shortcomings---things it fails to explain and future theoretical progress may explain. I don't see the present shortcomings of physics as evidence of the existence of something invisible. So what is this "mounting evidence" you are talking about?

And what do you mean by "accidents"? Do you mean permanently unexplainable? Human understanding is in its infancy--- just getting started--- our understanding is growing, as is our ability to explain.

I doubt very much that we are at some special point in history where our understanding meets an insuperable barrier of "more and more evidence" and stops growing.

The "accidents" I'm talking about are spontaneous symmetry breaking events. The standard model of particle physics already includes some spontaneous symmetry breaking, and unified theories tend to include much more.

 

[Chalnoth]

The above discussion shows that the anthropic principle, however characterised, is not a principle of science. It is philosophy. There is nothing wrong with philosophy. It is often very important in driving the guesses of theoretical physicists. But, questions like: "are there other universes out there that we cannot interact with because our laws of physics do not apply in such universes?" are questions for philosophical debate. One can argue about the reasoning behind the existence or non-existence of multiple universes. But it is not a scientific argument. It is a philosophical debate - at least at this point.

So I suggest this thread be moved to the "PF Lounge>General Discussion>Philosophy" board.

AM

It is fundamentally impossible to consider science without considering philosophy, just as it is fundamentally impossible to consider physics without considering mathematics. Philosophy isn't somehow "outside of science", just as mathematics is not "outside of physics".

 

[Tanelorn]

Chalnoth said "It is fundamentally impossible to consider science without considering philosophy, just as it is fundamentally impossible to consider physics without considering mathematics. Philosophy isn't somehow "outside of science", just as mathematics is not "outside of physics"."


I fully agree with Chalnoth's statement, in fact Physics used to be called Natural Philosophy.
The only thing we must never forget is to never turn a blind eye to observational evidence simply because it doesn't fit in with our preferred view or Philospophy or understanding. All data is good data when properly weighted.


Can I ask if the anthropic principle also includes the admittedly unlikely possibility that the universe continues to this day to somehow make cosmological adjustments to prevent the universe from becoming too dense? I am thinking here about Dark Energy which might actually be beneficial in preventing massive galaxies from becoming overly dense and hence highly active, which would doubtless be very harmful to life, or any other complex matter energy systems, near such locations? There may be other examples of things which have changed over time, but I am not sure how we would tell whether they are part of some greater type of control system. eg. Black hole and galaxy formation seems to behave like a control system again preventing galaxies from becoming too big, perhaps also suggesting the anthropic principle?


Re: The Multiverse, I find it difficult to believe that there are currently other space times other that our own simply because I find I need some proof to believe that something exists first (probably why I often feel I am an atheist!) It would be very interesting to learn of solid evidence for other BBs before our own in our own space time universe, but I just don't know what proof exists for this. I fully accept that our universe is splitting into a multitude of observable universes, but whether this constitutes a multiverse is up to the agreement on a definition by everyone. I suspect it isn't the right word.

 

[Andrew Mason]

It is fundamentally impossible to consider science without considering philosophy, just as it is fundamentally impossible to consider physics without considering mathematics. Philosophy isn't somehow "outside of science", just as mathematics is not "outside of physics".

I suppose. But mathematics is not a science either. There are separate boards for mathematics questions. Perhaps there should be more boards for philosophy.

AM

 

[Tanelorn]

It appears that we are very lucky that cosmic radiation levels are not 10 or 20dB higher or that the Earths protective qualities attenuation is not 10 or 20dB less:


http://en.wikipedia.org/wiki/Health_threat_from_cosmic_rays


This is another reason why the anthropic principle may have point. Larger denser galaxies could be quite toxic, hence be thankful for dark energy for helping to keep galaxies from merging into ever greater sizes! Does this make sense?

 

[island]

The only contingent statement in the weak anthropic principle is the existence of observers. We observe that we exist. That is all that is required for it to apply.

That isn't the weak anthropic principle or any other principle nor is it even a selection effect.

 

[island]

It appears that we are very lucky that cosmic radiation levels are not 10 or 20dB higher or that the Earths protective qualities attenuation is not 10 or 20dB less:http://en.wikipedia.org/wiki/Health_threat_from_cosmic_raysThis is another reason why the anthropic principle may have point. Larger denser galaxies could be quite toxic, hence be thankful for dark energy for helping to keep galaxies from merging into ever greater sizes! Does this make sense?

Yes, and it would fall into the category of a "goldilocks constraint" if there is a runaway effect involved... if it was higher, then conditions would rapidly fall off of a cliff to become MUCH higher, and if it is lower, then it falls off of a cliff to be MUCH lower and very far away from anything that is even remotely conducive to carbon based life:

http://abyss.uoregon.edu/~js/images/instability.gif

These balance points are diametrically opposing in nature, like the Earth exists precariously balanced between the runaway tendencies that you find on Venus and Mars:

http://www.astronomynotes.com/solarsys/s9.htm

Like the structure of the universe is observed to be balanced between runaway expansion and runaway re-collapse, because any change in the value of the cosmological constant would result in a dramatic difference either way, and it is this ***structure defining*** commonality that most clearly indicates that we may be directly linked to the mechanism that defines the structure of the universe via a bio-oriented cosmological principle.

This cosmological principle is what observation calls for, and this is what is most willfully ignored by "Copernicanism" practicing scientists, and my last buck says that it's also the reason that we have no final theory, nor even a complete theory of quantum gravity. It's the reason that we have string theories instead of science, and it's the reason that the large hadron collider will find nothing that supports "higher dimensions".

 

[Tanelorn]

I think that my point here is that, ok we might just happen to live in the one universe in 10^30 that can result in complex forms of baryonic matter and intelligent life, but if the expansion of the universe had not accelerated around 6B years ago, then in the distant future we might be left with toxic galaxies and many extinctions of intelligent life within them.

I will call this the continuing anthropic principle (CAP) as opposed to SAP FAP and CRAP :)

http://en.wikipedia.org/wiki/Anthropic_principle#The_Anthropic_Cosmological_Principle


In support of the Anthropic principle if one found a coin stood on its edge one would be less inclined to think that it got there through tossing and more inclined to think that something non random was responsible. But to disprove the principle outright the observer would somehow have to find many examples of other random universes that are unstable or failed in some way to produce baryonic matter as interesting as our own. I am assuming that we are at least sometimes intelligent down here. :)

In conclusion, we can never know the answer to this question with certainty and hence it becomes a faith based concept. Even the increased expansion of the universe 6B years ago could be random along with all the other lucky coincidences.

 

[Chalnoth]

That isn't the weak anthropic principle or any other principle nor is it even a selection effect.

Sure it is. It is a simple statement of truth: observers can only possibly observe conditions that are compatible with their existence. A direct conclusion of the weak anthropic principle is that we cannot make any statement a priori about the existence or non-existence of regions where life is impossible outside of our observable universe. This is another way of saying that we should not assume a priori that every region of space beyond our cosmological horizon is habitable.

Because of this principle, whenever we judge how likely or unlikely a quantity seems, we must always limit the range of the quantity in question to a regime where life is possible. Failure to do so will bias the result.

 

[island]

I think that my point here is that, ok we might just happen to live in the one universe in 10^30 that can result in complex forms of baryonic matter and intelligent life, but if the expansion of the universe had not accelerated around 6B years ago, then in the distant future we might be left with toxic galaxies and many extinctions of intelligent life within them.

I will call this the continuing anthropic principle (CAP) as opposed to SAP FAP and CRAP :)

http://en.wikipedia.org/wiki/Anthropic_principle#The_Anthropic_Cosmological_Principle


In support of the Anthropic principle if one found a coin stood on its edge one would be less inclined to think that it got there through tossing and more inclined to think that something non random was responsible. But to disprove the principle outright the observer would somehow have to find many examples of other random universes that are unstable or failed in some way to produce baryonic matter as interesting as our own. I am assuming that we are at least sometimes intelligent down here. :)

In conclusion, we can never know the answer to this question with certainty and hence it becomes a faith based concept. Even the increased expansion of the universe could be random along with all the other lucky coincidences.

It isn't the unexpected appearance of the coin, it's common link that the balance has to the conditions necessary for carbon based life, and to the structure of the universe, itself. I edited my previous post, sorry.

Remember that for a strong interpretation, we're only looking for evidenced plausibility for a dynamical structure principle that requires life, like an energy conservation law that requires carbon based life to appear over a specifically defined region of the observed universe, and at an equally specific time, as a necessary function of the thermodynamic process, for example, and FYI the physics is far from limited to Earth, although it is limited to a specific region and time.

 

[Tanelorn]

Chalnoth said "we cannot make any statement a priori about the existence or non-existence of regions where life is impossible outside of our observable universe."

Even if Physicists say that the whole universe is isotropic and homogenous? We can't have it both ways :)

 

[Tanelorn]

Island,

Supposing we found a hundred universes all with their own big bangs and ours is the only one that resulted in life. What does this tell us about AP?

Supposing we found a hundred universes all with their own big bangs and all of them resulted in life. What does this tell us about AP?

Supposing we found a hundred universes all with their own big bangs and none of them resulted in life. What does this tell us about AP? This scenario can be discounted for sure because of our existence, but it may illustrate when AP is false.

 

[island]

The "natural" quantum expectation derives a vacuum energy density that is about 120 orders of magnitude greater than we observe, so, without a multiverse, there must be a suppression mechanism at work now that constrains the vacuum energy density by at least 120 orders of magnitude. The ratio between the expected density and what's actually observed is often called the cosmological constant problem. It has perplexed physicists for at least 50 years and is the reason that Brandon Carter threw up his hands to first principles to put forth the weak cop-out on science, which only works to resolve the problem via a multiverse.

There is no weak anthropic principle without a multiverse, or a dynamical structure principle that explains why the highly pointed commonalities that we share with the structure of the universe are just a coincidence.

 

[island]

Island,

Supposing we found a hundred universes all with their own big bangs and ours is the only one that resulted in life. What does this tell us about AP?

Supposing we found a hundred universes all with their own big bangs and all of them resulted in life. What does this tell us about AP?

Supposing we found a hundred universes all with their own big bangs and none of them resulted in life. What does this tell us about AP? This scenario can be discounted for sure because of our existence, but it may illustrate when AP is false.

Right, as I've explained, all you need is a complete theory of quantum gravity, or a final theory that justifies these universe and you can claim them all day, but my point is that we have only the observation and the natural quantum expectation without those requirements, and the observation is very apparently telling us something that is being willfully ignored.

 

[Tanelorn]

Island, please don't beat about the bush, do you suspect that our universe was designed for intelligent life to develop (and the conditions to help it continue)? I sometimes think I do. I am just not sure which side of the argument you are making!

I note your point about willfully ignored vacuum energy. I cannot help with this, it is beyond my depth.


I also just saw your statement, which is pretty strong stuff:

"This cosmological principle is what observation calls for, and this is what is most willfully ignored by "Copernicanism" practicing scientists, and my last buck says that it's also the reason that we have no final theory, nor even a complete theory of quantum gravity. It's the reason that we have string theories instead of science, and it's the reason that the large hadron collider will find nothing that supports "higher dimensions"."

Personally I dislike string theory just because they have added more dimensions of space, apparently up to 11 in order to explain the existence of fundermental particles. So rather than simplfying or unifying the laws of the Physics, to me they seem to have done the opposite here. It seems almost like having to resort to using magic (new dimensions) to explain the inexplainable, perhaps they could have used another word other than dimensions..

 

[Chalnoth]

Chalnoth said "we cannot make any statement a priori about the existence or non-existence of regions where life is impossible outside of our observable universe."

Even if Physicists say that the whole universe is isotropic and homogenous? We can't have it both ways :)

I think we'd be foolish to believe that that description is anything more than an approximation.

 

[Chalnoth]

The "natural" quantum expectation derives a vacuum energy density that is about 120 orders of magnitude greater than we observe, so, without a multiverse, there must be a suppression mechanism at work now that constrains the vacuum energy density by at least 120 orders of magnitude. The ratio between the expected density and what's actually observed is often called the cosmological constant problem. It has perplexed physicists for at least 50 years and is the reason that Brandon Carter threw up his hands to first principles to put forth the weak cop-out on science, which only works to resolve the problem via a multiverse.

That's not a cop-out, however, because the vast majority of the conceivable values of the cosmological constant are not observable. The observed value isn't nearly so apparently unlikely once we take the prior of requiring life (specifically, in this case, requiring the formation of structure).

It is you who are making the unreasonable assumption that the explanation of the cosmological constant must be a result of some sort of suppression mechanism. This just isn't the case, because we have a selection effect at work.

There is no weak anthropic principle without a multiverse, or a dynamical structure principle that explains why the highly pointed commonalities that we share with the structure of the universe are just a coincidence.

No, the fact that the weak anthropic principle appears to explain so much is just more evidence in favor of a multiverse. It makes no assumptions of a multiverse in and of itself. It is simply a necessarily true statement.

 

[Haelfix]

The evidence for the multiverse is indeed strong (unfortunately), but I don't think it is influenced by the usefulness or not of the anthropic principle.

Indeed, its simply follows from these points (and many others):

1) Inflation is favored empirically (eg the prediction of the nearly scale invariant Sunyaev Zeldovich spectrum that was subsequently observed).
2) The observed cosmological constant is positive.
3) The observed cosmological is many orders of magnitude away from its natural value.
4) There appears to be a great deal of finetuning in low energy physics.
5) There appears to be a vast discretum of semiclassical solutions that contain the standard model in quantum field theory.

Point 1 implies that our visible universe is incredibly tiny relative to its natural distance scale, and that there is no obvious theoretical reason why inflation should only happen at one particular spacetime event. Point 2 implies that the final state of our visible universe approaches DeSitter asymptotically. The flip side of this is that the timescales become naturally huge, which suggests that the solution is metastable due to the existence of tunneling solutions (found in the 80s by Coleman, De Luccia and many others) with tiny but not infinitely tiny probabilities. Implying yet again that we are but a small part of a much bigger whole.

3+4 seems to imply that the mathematics of our universe seems to contain some insanely unlikely accidents within its actual dynamical laws, with no obvious explanation.

Point 5 says that there is a landscape of low energy metastable vacua that approximates our low energy world arbitrarily closely. Since we only exist in identically 1 of these, an obvious guess for a mathematical selection principle would be something like a multiverse.

I stress that this is in some sense, imposed on us by observation. No one would believe this crazy story if it wasn't for the fact that we had evidence for it. So while none of this is airtight, its pretty hard to imagine ways around it.