Smolin: Anthropery is not science

[marcus]

this just out

An new essay by Smolin, to be a part of a book that Cambridge University Press is publishing (edited by Bernard Carr et al)

http://arxiv.org/hep-th/0407213

"It is explained in detail why the Anthropic Principle cannot yield any
falsifiable predictions and therefore cannot be a part of science."


Smolin offers an alternative that he argues does yield falsifiable predictions which, although it has not so far been shown false, is nevertheless vulnerable to refutation by observations now planned or in progress.

 

[sol2]

this just out

An new essay by Smolin, to be a part of a book that Cambridge University Press is publishing (edited by Bernard Carr et al)

http:arxiv.org/hep-th/0407213

"It is explained in detail why the Anthropic Principle cannot yield any
falsifiable predictions and therefore cannot be a part of science."


Smolin offers an alternative that he argues does yield falsifiable predictions which, although it has not so far been shown false, is nevertheless vulnerable to refutation by observations now planned or in progress.

Did you have a proper link for this Marcus?

 

[marcus]

Did you have a proper link for this Marcus?

There I fixed it, earlier i wrote http:arxiv
instead of http://arxiv .
thanks for getting me to correct it.

Hi sol,
you know I have never gotten much interested in the Anthropic
business in string theory, so i am posting this in case other people
want to discuss it. If no one wants to that's fine with me.

Smolin's article is also about the Multiverse business, how there could
be lots of other regions with different fundamental constants---different alpha, different Lambda---essentially different physical laws.

He has an idea how universes might EVOLVE by those values of alpha and Lambda being favored if they were in the right range to cause the universe to have a long life and make lots of baby universes-----good genes are those that get passed on a lot.

Again I have to say that this idea may be a fascinating one but I didnt personally get involved with it. It may actually be an experimentally testable theory explaining why our alpha is what it is: very close to 1/137 (which happens to be so good for the existence of complex life and long-burning stars.) but I put it out just in case it might interest others.

the paper is called

"an alternative to the anthropic principle"

the link should work now

 

[Chronos]

I find that unpalatable. The anthropic principle, I believe, is the only 'given' that is absolute. The fact we are here [and I presume most everyone will agree with that] precludes solutions that forbid our existence. I'm not excluding the possibility of universes where creatures, such as us, do not exist. Just excluding the possibility they are relevant.

 

[sol2]

Thanks Marcus

The Anthropic Landscape of String Theory

Leonard Susskind

Leonard Susskind

In this lecture I make some educated guesses, about the landscape of string theory vacua. Based on the recent work of a number of authors, it seems plausible that the lanscape is unimaginably large and diverse. Whether we like it or not, this is the kind of behavior that gives credence to the Anthropic Principle. I discuss the theoretical and conceptual issues that arise in developing a cosmology based on the diversity of environments implicit in string theory.

http://arxiv.org/abs/hep-th/0302219

On page 11 Smolin's article also refers to the use of the word Landscape?

Of course we all like to have proof of all these theoretics.

 

[Chronos]

Ranting. I object to using unobserved extra dimensions to explain the four we can observe. Apologies to all. I am old, stubborn, and won't let go of background independent relativity until somebody sticks the observational evidence in my face.

 

[Chronos]

More ranting: I wasted 4 years of my life trying to prove Einstein was wrong [keyword: wasted]. He was not wrong. Even his 'cosmological constant' was totally on target. Einstein saw more than we even dreamt of seeing.

I really get frustrated when the truly brilliant people here go off on tangents. What a waste of brain power. I will never be as smart as you guys. I lurk in the background and watch.

 

[marcus]

More ranting: I wasted 4 years of my life trying to prove Einstein was wrong [keyword: wasted]. He was not wrong. Even his 'cosmological constant' was totally on target. Einstein saw more than we even dreamt of seeing.
...

Hello Chronos, let's not quarrel about Anthropism. I for one am not concerned with it. (however Smolin may have some useful points to make, why not read his essay?)

I think all he is saying is that a scientific theory is meaningful only to the extent that it is falsifiable---runs the risk of making predictions which can cause it to be shot down.

so a principle can be a valid part of Philosophy and of one's system of beliefs without necessarily being a part of science. this is a rather strict idea of Science but at least it is clear---a scientific theory is meaningful only to the extent that it is vulnerable to empirical refutation.

I'm cool with that, I have a number of important tenets and faiths and convictions that are not empirically testable. Also i like certain poems.
It is obvious to me this is an absolutely wonderful universe and very conducive to a happy wholesome life (if we could just get our act together).

So I propose to believe whatever you say in an Anthropic vein---to agree with you wholeheartedly----but not to consider it part of science. Do you think we can manage that in a spirit of peace and fellowship (if some problem with it please say)

are you claiming Curmudgeon status BTW? this is or should be a position of high honor

 

[Olias]

More ranting: I wasted 4 years of my life trying to prove Einstein was wrong [keyword: wasted]. He was not wrong. Even his 'cosmological constant' was totally on target. Einstein saw more than we even dreamt of seeing.

I really get frustrated when the truly brilliant people here go off on tangents. What a waste of brain power. I will never be as smart as you guys. I lurk in the background and watch.

Einstein was more than right, but I believe that his 'wrong' lines of workings were actually deliberate! May be due to the surrounding Human and scientific worldwide problems of the day. Some of the so called greatest minds of early last century mocked Einstein and his 'later years', the much quoted sentence of:Einstein wasted the later years of his life working on an Unified Field Theory, which yeilded no scientific fruits?

Or...did he?

It is no coincedence that Some of Einsteins greatest work is placed in specific writings, "Time-locked" for "future" generations hidden (so presicely) between the pages of the very distinct book , which has the title:Albert Einstein-Out Of My Later Years.

This is Einsteins Magnum-Opus, ..you just have to read its content in a certain way..with the awe of a Child of unbiased learning.

 

[selfAdjoint]

For recent work on the Unified Field Theory by a professional physicist, see
http://www.einstein-schrodinger.com/.

 

[marcus]

Ranting. I object to using unobserved extra dimensions to explain the four we can observe. Apologies to all. I am old, stubborn, and won't let go of background independent relativity until somebody sticks the observational evidence in my face.

I thought about making this my sig
(as a quote from you)
I wouldn't excuse it as ranting though, Or apologize
for steadfast rejection of the unobserved.

In one of the historical parts of Rovelli's book he argues that
major scientific advances have not been achieved, as a rule,
by "Great Leaps of Imagination" but actually in a conservative
manner by taking seriously what you already had that worked
and modifying it only as much as you had to.

One of his examples was 1905 Special rel---something about
taking seriously both galilean relativity and Maxwell equations
and not wanting to let go of either-----and not going for novelty
but simply making the minimum modification necessary (different time for
different folks) to get consistency. I'm not sure I got this right
but there is a philosophical part of that book that argues for this
kind of conservative taking seriously the core of what works and
avoiding the Wild Goose of novelty.

It struck me as a good motto so I tried to imagine it as a sig.
The following is a test (not a real sig)

---------
What extra dimensions? I'll hold to background independent relativity until observational evidence shows it wrong.
---Chronos

 

[sol2]

Any one of us could be the negative and from that, a position taken.


I like Olias's perspective on what could have "spaces inbetween" and find that in future years Einstein's implication still reverberating(what is the dimensional significance of this statement if we consider Ramaujan view about the reality we live) and holding a collider eye to the very fabric. I mean we take reductionistic processes and we find this vast field of energy, being really fuzzy, we had only gone so far to Planck length? So we had to explain the energy? Some particle trails leave us wondering and the rest of the energy?

So what lies beneath? Geometrically, the necessity of consistancy, cries for some continuance, expressed logically. What had been learned so far in these extension through this historical journey? Can LQG and M Theory succeed in this quest?

Are we so wrong then, if we look at emergent realities that one might have built glass palaces for living theoretcally in , while we look at all the rooms? I do not think we should all be faulted at trying to explain this reality, and at the same time find discoveries along the way.

Smolin recognizes the philosphcal journey that must be taken and speaks to the rational and logical requirement such journies must take. Much like Peter Woit on demands for scientific validation require a more fundamental approach, but still to me, the imaginiative valution of theoretical journies are quite artistical embued. You have to be creative as well as logical. I think the etiquette of scientifdic pursuate is generally well understood.

We do not discard the anomalies of perception(Kuhn) that cause great consternation in what is wrong with our views, that we set it all aside becuase it just doesn't make sense. You plug away. Some did not not find the connecting circumstance so they discard the view.

My statement should read opposite Marcus's and I admire Marcus determinations. The Solvay format is very much alive when we accept the spirit of it

-----------------------------

What extra dimensions? I'll hold to the background dependant

 

[Njorl]

I find that unpalatable. The anthropic principle, I believe, is the only 'given' that is absolute. The fact we are here [and I presume most everyone will agree with that] precludes solutions that forbid our existence. I'm not excluding the possibility of universes where creatures, such as us, do not exist. Just excluding the possibility they are relevant.

Please be aware that there are many anthropic principles. They run the gamut from simple common sense to the metaphysical. I haven't looked carefully, but the author might only be assailing the cosmological anthropic principle, as espoused by Barrow and Tipler.

Njorl

 

[sol2]

So again Smolin Takes us to the Edge?

You have to understand his mode of operandi? There is always this proverbial headshaking that goes on, and a consolidation of factors, when you become spread out? Sort of like a greg egans Gravity well picture?


http://citebase.eprints.org/cgi-bin/search?submit=1;author=Smolin%2C%20Lee

An assessment is offered of the progress that the major approaches to quantum gravity have made towards the goal of constructing a complete and satisfactory theory. The emphasis is on loop quantum gravity and string theory, although other approaches are discussed, including dynamical triangulation models (euclidean and lorentzian) regge calculus models, causal sets, twistor theory, non-commutative geometry and models based on analogies to condensed matter systems. We proceed by listing the questions the theories are expected to be able to answer. We then compile two lists: the first details the actual results so far achieved in each theory, while the second lists conjectures which remain open. By comparing them we can evaluate how far each theory has progressed, and what must still be done before each theory can be considered a satisfactory quantum theory of gravity. We find there has been impressive recent progress on several fronts. At the same time, important issues about loop quantum gravity are so far unresolved, as are key conjectures of string theory. However, there is a reasonable expectation that experimental tests of lorentz invariance at Planck scales may in the near future make it possible to rule out one or more candidate quantum theories of gravity.

http://citebase.eprints.org/cgi-bin/citations?id=oai:arXiv.org:hep-th/0303185

So we are back to Earth and have taken our heads out of the clouds have we? Its funny how you can look up at the clouds and see this changing reality, and if you look hard enough, for sure, there seems to be this animal or that face?

If men/women could see to the very heart of the matters(laughlin, Einstein[slide of light]Feynman[integral paths]), what allowed them the greater vision, to pick out what exists in nature(patterns), to know with all that information at hand, they could have seen something else?

Do anomalies of perception pay off? Maybe Einstein asks us to look deeper?They most certainly do in science

 

[marcus]

Smolin introduced the "Landscape" in 1995

It is interesting to note that Lenny Susskind and other string theorists have recently (essentially since Kachru's paper and the 10¹⁰⁰ possible string vacuums) become converts to Smolin's 1995 idea of
the "Landscape" of possible parameters of the Standard Model----essentially an evolutionary landscape of possibility for the laws of physics.

I went back to Smolin's landmark 1995 paper where he introduced the concept of the Landscape

http://arxiv.org/gr-qc/9505022
Cosmology as a problem in critical phenomena
Lee Smolin
(see page 33)

"...We can then make predictions about our world if there are statistical predictions that can be made about the properties of randomly chosen members of this ensemble. We can do this because this theory is isomorphic to models of biological evolution, in which natural selection is described in terms of the evolution of probability distributions on fitness landscapes.

As a result there is a natural mechanism of cosmological self- organization, that is formally analogous to biological natural selection. It goes like this. We may consider the space of parameters of low energy physics to be analogous to the space of genes. On this space there is a “fitness” function, which is the average number of black holes produced by a region of the universe that expands from a bounce.

Now, just like the fitness functions of biology, this function is strongly variable, as I said in our universe it is quite large, and there are simple astrophysical arguments that tell us that with many values of the parameters it will be much smaller. The reason the fitness function is strongly variable is worth mentioning: it is that it is not easy to make a black hole. In our universe, a black hole can only be made if a large amount of matter can be compressed into a very small space, and for this to happen there must be rather special circumstances. The fact that this happens at least once a century in each galaxy..."

the more I see of Smolin's work the more it impresses me

In 1995 he is talking about quantum gravity removing the Black Hole singularity and replacing it by a quantum bounce that continues into an extension of our spacetime which (because of the horizon) we can't detect signals from and which may therefore be considered (if one wishes) as another universe---one with parameters (fundamental constants) to some extent inherited from ours.

And dammit if yesterday that postdoc Leonardo Modesto didn't go and put up his paper which uses quantum gravity to eliminate the Black Hole singularity and replace the classical ex-singularity with a bounce---and a continuation of spacetime.

But the stringers didnt go Landsc ape AFAIK
until
S. Kachru, R. Kallosh, A. Linde, S. P. Trivedi, de Sitter Vacua in String Theory hep-th/0301240
that is, until january 2003
and even then they seem to be appealing to Anthropery!

Smolin saw the landscape in 1995 and called it a landscape by analogy
with the pre-existing concept in Evolutionary Biology
(which does not require the Anthropic Principle!)

 

[sol2]

You have to remember Marcus, that each one of these guys is being influence by the scholarly envirnoment around them. This does not limit them to branches, but forces them tospeak to new starting points in their considerations.

They are all trying to describe the same thing but in different ways?

Some like Chernekov's version, and is pleasing to the color palette of experienece? Some like pure abstractness.

Pretend you were raised in the wild and had never seen straight lines?

 

[sol2]

It is interesting to note that Lenny Susskind and other string theorists have recently (essentially since Kachru's paper and the 10¹⁰⁰ possible string vacuums) become converts to Smolin's 1995 idea of
the "Landscape" of possible parameters of the Standard Model----essentially an evolutionary landscape of possibility for the laws of physics.

I went back to Smolin's landmark 1995 paper where he introduced the concept of the Landscape

http://arxiv.org/gr-qc/9505022
Cosmology as a problem in critical phenomena
Lee Smolin
(see page 33)

"...We can then make predictions about our world if there are statistical predictions that can be made about the properties of randomly chosen members of this ensemble. We can do this because this theory is isomorphic to models of biological evolution, in which natural selection is described in terms of the evolution of probability distributions on fitness landscapes.

As a result there is a natural mechanism of cosmological self- organization, that is formally analogous to biological natural selection. It goes like this. We may consider the space of parameters of low energy physics to be analogous to the space of genes. On this space there is a “fitness” function, which is the average number of black holes produced by a region of the universe that expands from a bounce.

Now, just like the fitness functions of biology, this function is strongly variable, as I said in our universe it is quite large, and there are simple astrophysical arguments that tell us that with many values of the parameters it will be much smaller. The reason the fitness function is strongly variable is worth mentioning: it is that it is not easy to make a black hole. In our universe, a black hole can only be made if a large amount of matter can be compressed into a very small space, and for this to happen there must be rather special circumstances. The fact that this happens at least once a century in each galaxy..."

the more I see of Smolin's work the more it impresses me

In 1995 he is talking about quantum gravity removing the Black Hole singularity and replacing it by a quantum bounce that continues into an extension of our spacetime which (because of the horizon) we can't detect signals from and which may therefore be considered (if one wishes) as another universe---one with parameters (fundamental constants) to some extent inherited from ours.

And dammit if yesterday that postdoc Leonardo Modesto didn't go and put up his paper which uses quantum gravity to eliminate the Black Hole singularity and replace the classical ex-singularity with a bounce---and a continuation of spacetime.

But the stringers didnt go Landsc ape AFAIK
until
S. Kachru, R. Kallosh, A. Linde, S. P. Trivedi, de Sitter Vacua in String Theory hep-th/0301240
that is, until january 2003
and even then they seem to be appealing to Anthropery!

Smolin saw the landscape in 1995 and called it a landscape by analogy
with the pre-existing concept in Evolutionary Biology
(which does not require the Anthropic Principle!)

It is important for me to see the sequence of events as they are unfolding for you Marcus, and by looking to Baez, you are true to form with guiding principals?

John Baez
String theorists are pragmatic in a certain sense: they don't mind using a background, and they don't mind doing what physicists always do: approximating a divergent series by the sum of the first couple of terms. But this attitude doesn't solve everything, because right now in string theory there is an enormous "landscape" of different backgrounds, with no firm principle for choosing one. Some estimates guess there are over 10100. Leonard Susskind guesses there are 10500, and argues that we'll need the anthropic principle to choose the one describing our world:

http://math.ucr.edu/home/baez/week206.html

 

[Ontoplankton]

This is exactly what I was complaining about earlier, in the "not even wrong" thread. Smolin claims the anthropic principle isn't falsifiable. Of course it isn't: it's an epistemological or decision-theoretical principle, not a contingent claim about the physical world. The question whether it's valuable is a philosophical, not scientific question. The same is true of the "principle of mediocrity".

Okay, so then we can read Smolin as saying that it's theories like eternal inflation, with its multiverse, that aren't falsifiable. But then he claims that non-falsifiable theories should automatically be taken as false. I think this is bizarre: we have no business telling nature how to behave, and whether a theory is experimentally testable has no bearing on whether it's actually true (though of course, the more tests a theory passes, the more likely it is to be correct).

The rest of the paper left a bad taste in my brain as well. I'm not convinced Smolin's reproducing-universes theory is any more falsifiable than e.g. eternal inflation: (IIRC) he refers to the fact that under his theory "almost all" universes should have parameters optimized for black hole production. This seems like a dubious claim to me, given that (IIRC) there are infinitely many universes under his theory, making "almost all" a difficult concept. More importantly: he can't claim that observing different parameters would falsify his theory, because our universe could be one of the exceptions. Such an observation would make his theory less probable, but then we're out of Popper-land and into Bayesian probability theory and decision theory, which is IMO the only place where all these anthropic questions make sense in the first place (Smolin doesn't even mention it).

It looks to me like Smolin misunderstands the relevance of Weinberg's explanation of the cosmological constant as well. It's not just that the cosmological constant can be predicted from the observed fact that there are galaxies; we can explain the CC by the anthropic principle because all the observers in the universes with too high cosmological constants just aren't there.

Smolin dismisses the "doomsday argument" as ridiculous because of an objection that is dealt with in the first entry of the FAQ and another that is dealt with in question 6. All this leads me to think he hasn't even bothered to read up on what philosophers think on the subject (or googled for a minute). He's much more fanatical than the strength of his arguments allows, just like in his book Three Roads to Quantum Gravity (which I recall as having interesting science content but trying to force badly-argued philosophy on me).

Blegh. Sorry for ranting.

 

[sol2]

Onto,

You have to understand this is a cosmological view that had to be defined, and this is being looked at in different ways?

If critical density of OMega is being established, then what is happenng to our unverse? Remember we are talking about billions of years here and the universe has allowed us to consider the dynamics taking place.

You must undertsand where Smoln and those of LQG(SRians) have placed themselves in their attempts at discribing the nature of this universe and how M theory(GRaniums-members of the http://astrosun.tn.cornell.edu/courses/astro201/images/merc_adv.gif ) is doing likewise. These are the new flower children of science

 

[marcus]

This is exactly what I was complaining about earlier, in the "not even wrong" thread. Smolin claims the anthropic principle isn't falsifiable. Of course it isn't:...

I am trying to sort this out. here are some quotes. Let's be sure we are all talking about the same AP and understand Smolin's critique of it:

"I have chosen a deliberatively provocative title, in order to communicate a sense of frustration I’ve felt for many years about how otherwise sensible people, some of whom are among the scientists I most respect and admire, espouse an approach to cosmological problems that is easily seen to be unscientific. I am referring of course to the anthropic principle. By calling it unscientific I mean something very specific, which is that it fails to have a necessary property to be considered a scientific hypothesis. This is that it be falsifiable. According to Popper[1], a theory is falsifiable if one can derive from it unambiguous predictions for doable experiments such that, were contrary results seen, at least one premise of the theory would have been proven not to apply to nature."

"...I also have no argument against straightforward consideration of selection effects, so long as the conditions invoked are known independently and not part of a speculative theory that is otherwise unsupported by any evidence. I will discuss this in some detail below, but the short version is that there simply is a vast logical difference between taking into account a known fact, such as the fact that most of the galaxy is empty space, and arguing from a speculative and unproven premise, such as that there is a large ensemble of unseen universes.

In recent discussions, the version of the anthropic principle that is usually put forward by its proponents as a scientific idea is based on two premises.

• A There exists (in the same sense that our chairs, tables and our universe exists) a very large ensemble of “universes”, M which are completely or almost completely causally disjoint regions of spacetime, within which the parameters of the standard models of physics and cosmology differ. To the extent that they are causally disjoint, we have no ability to make observations in other universe than our own. The parameters of the standard models of particle physics and cosmology vary over the ensemble of universes.

• B The distribution of parameters in M is random (in some measure) and the parameters that govern our universe are rare.

This is the form of the Anthropic Principle most invoked in discussions related to inflationary cosmology and string theory, and it is the one I will critique here. Here is the basic argument why a theory based on A and B is not falsifiable..."

Onto, Chronos, sol, and others, are we all talking about the same thing in this thread? If so, let's proceed.

 

[marcus]

Onto you said in post #18
"Okay, so then we can read Smolin as saying that it's theories like eternal inflation, with its multiverse, that aren't falsifiable. But then he claims that non-falsifiable theories should automatically be taken as false."

Where in the paper does he claim that?

we shouldn't attribute claims to the author that he doesn't make,
so you probably have a particular paragraph or sentence in mind,
please point it out since i can't find it

 

[Ontoplankton]

Onto, Chronos, sol, and others, are we all talking about the same thing in this thread? If so, let's proceed.

We are. What Smolin calls the anthropic principle isn't actually the anthropic principle; it's the theory that there is a multiverse where different universes have different constants etc. and only some of them allow for the existence of physicists. In the rest (after the first paragraph) of my post, this version of the anthropic principle was what I was talking about.

 

[Ontoplankton]

Onto you said in post #18
"Okay, so then we can read Smolin as saying that it's theories like eternal inflation, with its multiverse, that aren't falsifiable. But then he claims that non-falsifiable theories should automatically be taken as false."

Where in the paper does he claim that?

Okay, that wasn't a direct quote; I take it back.

However, he does say e.g.:

"scientists have an ethical imperative to consider only falsifiable theories as possible explanations of natural phenomena",

which IMO comes down to the same thing.

 

[setAI]

Okay, that wasn't a direct quote; I take it back.

However, he does say e.g.:

"scientists have an ethical imperative to consider only falsifiable theories as possible explanations of natural phenomena",

which IMO comes down to the same thing.

but he doesn't say non-falsifiable theories are false- just not part of SCIENCE- which is axiomatic given the definition of science- the fundamental eternal/infinite nature of the Universe is another example of such an idea- one I would claim is both necissarily TRUE and at the same time UNSCIENTIFIC due to unfalsifiability

Smolin is a scientist- therefore he wants to deal with scientific ideas- not existential/ontological tautologies- ideas for philosophers and artists to explore- this is where I COME IN

___________________________

/:set\AI transmedia laboratories

http://setai-transmedia.com

 

[Ontoplankton]

Stupid thought:

The theory that our universe is infinite is falsifiable: if we found an edge, or if we found out it's topologically weird so that it goes in circles (in all directions), then the theory would be falsified.

The theory that our universe is finite is unfalsifiable. After all, to falsify the theory, we would need to prove it's infinite, and there's no way to do that.

Therefore, by Smolin's reasoning, all talk of finite universes is unscientific. Scientists have an ethical imperative (!) to not even consider the possibility that the universe might be finite.

Popperianism is really weird.

(edit: this isn't completely fair, of course, but it's almost fair. Popper-abuse is very easy, and I think Smolin falls for it a few times.)

 

[sol2]

Brane New World and the House of Cards

Thank you Marcus in helping to oreintate one back to a clear definition.


A lot of different things are popping into my mind on this issue, so I am finding myself all over the map. I hope you will be patient, because something seems to be metasizing in my brain in regard to this issue.

We have been presented with a way in which to discern the responsible feature and etiquette of science, as I once mentioned before.

So keeping your post in mind, things like solitons and discriptive ways in which this could be attacked in the brane scenarios and the cyclical nature of the cosmos seems to hold a logical position in my mind.

What was "nothing" and can such a universe ever have arisen from such a position? So to me something from nothing is nothing, and from that position, a certain logic said to me that I had to accept that the universe has always existed.

In doing that, I came to realize that such cyclical universe had a advantage, and such singularities no longer seemed a viable function and the potentials of dynamics within the context of the universe had a place in the perspective of the Life Cycles of Energy and Matter. This is a leading perspective on the nature of reality being defined from a starting point in terms of geometrical principals, and here such a question to have differential geometry arising from the understanding of the standard model from the brane very appealing? Brane intersections as descirbe in the analogy of the Moire effect?

But how will we ever see such dynamics in the hidden dimensions. So indeed something begins to form in mind about the nature of this reality and its possibilties.

http://physicsweb.org/objects/review/14/12/1/pw1412r1.gif

The anthropic principle is one of the more remarkable swindles in physics. Indeed it is metaphysics, and that is the essence of the problem for most physicists in accepting it. The anthropic logic is either immensely subtle, by arguing that we, via our mere existence, control the cosmos, or unabashedly naive, by setting aside any physics explanations that any ultimate theory of physics might reasonably be expected to deliver. Metaphysics lacks predictive power, the very core of physics. The anthropic principle is an extreme expression of our ignorance.

It may well be that the ultimate theory of cosmology will have anthropic ramifications. We are some way yet from this promised land. In the meantime, Hawking's book is a delight to read. It discusses questions that are at the forefront of current thinking about quantum gravity, yet for the most part is highly readable. It conveys the author's sense of wonder and awe at the cosmos, and - like a child stepping into the darkness - illustrates his tentative gropings towards the ultimate theory of everything.

http://physicsweb.org/article/review/14/12/1/1

One had to see where these early indications of perspective views had been arising from, and from a nutshell how was he seeing before Hawking's absolution in the GR17? Is there one of coming clean?

So this brings us back to ways in which to measure a responsible features underlying reality, and this is where two perspective views are saying which is more responsible?

 

[marcus]

The theory that our universe is infinite is falsifiable

Is this a theory? I do not understand what you mean by a scientific theory. General Relativity is a theory and it does not predict infinite, nor does it predict finite. It is not a premise of GR that the U is infinite. It is also not a premise of GR that the U is finite.

Finite and infinite are conclusions that one can draw, with a certain confidence level, from certain measurements using a scientific theory---namely Relativity.

The theory that our universe is finite is unfalsifiable. .

But again I have to ask, is it a scientific THEORY that the universe is finite? What good is using the phrase "the theory that our universe is finite" if, as I suspect, it does not refer to anything. There is, AFAIK, no such thing as a theory that U is finite---would have to make predictions and what prediction could it make? Theories have more parts to them than such an assertion.

Therefore, by Smolin's reasoning, all talk of finite universes is unscientific. Scientists have an ethical imperative (!) to not even consider the possibility that the universe might be finite.

Not true, one can test Relativity and within the context of that theory one can interpret measurements as implying the U is finite. The measurable parameter Omega, is it greater than 1? Unfortunately at the moment it is estimated at 1.02 +/- 0.02 and one cannot say for sure that it is >1
but someday we may be able to. Suppose next year the measurement says 1.02 +/- 0.01 (then with fair confidence we would be able to say finite as one of the conclusions of GR.) But finite is not the THEORY. Relativity is the theory and there are various ways to test it and within that context one can make statements derived from the theory using measurements.

OK maybe what you said was a joke, your suggests.

Popper-abuse is very easy, and I think Smolin falls for it a few times.

At what place in the essay does Smolin make a mistake? Please quote some lines from the essay that we can inspect.

Popperianism is really weird.

But Onto, you have not yet exhibited anything weird about what Smolin says! Let's focus on the essay and see if any of us can find anything wrong or out of line with it. So far your comments seem intended for fun. I appreciate the playfulness, but I would be glad if someone could find some substantial mistake in the essay.

BTW So far I haven't found anything out of line, but if I come across anything at all doubtful i will let y'all know. Wd like a critical reading of the essay on its own merits.

 

[marcus]

Thank you Marcus in helping to oreintate one back to a clear definition.

well I'm trying to sort it out as best as I can---and thanks in turn for your part!

my feeling there's no one right definition of any of these key words like scientific and anthropic. There's no one definition that will be right in all situations, but I have a strong urge to read this essay with some other people and to read it on its own terms-----understand it is saying with Smolins definitions.

BTW I am willing to believe and disbelieve a lot of things that aren't part of science! That's part of being human----you believe the universe is beautiful, that your wife has a good sense of humor, that a certain choral work is great and fun to sing, that your child is clever and charming and so on----or that a certain historian had the right perspective on the middle ages---or in some moral principles---that the US is or ought to be a constitutional representative democracy---it goes on endlessly

But the touchstone of a scientific theory is prediction allowing it to be tested. And for me this is just commonplace accepted truth I've heard all my life----dont need a philosopher to approve it! And Smolin uses this idea without needing to appeal to any authority. He gives a reasonable social argument of his own which makes sense.
The point about the scientific community is they can get agreement by empirical tests.

they arent like theologians who split up into various parties and sects and schools of thought

Everybody in the community, for the sake of the community's longterm cohesion and solidarity, should make sure not to propose theories that can't be tested. And the possibility of testing means the possibility of being shot down.

there can be other things: conjectures, scenarios, theories a-building which are under construction and not yet making predictions---but the goal is to get something falsifiable. always. until it is falsifiable it does not mean anything because it does not bet its life on a prediction about the world.

I think Smolin is saying that, and it makes sense to me.

And I think of Einstein publishing Gen Rel in 1915 and predicting that the light would be bent a certain angle, and by 1919 Eddington had gone to that island and looked and checked the angle---for a strange theory like that four years is not bad. this is the tradition and I think Smolin is there.

 

[setAI]

Stupid thought:

The theory that our universe is infinite is falsifiable: if we found an edge, or if we found out it's topologically weird so that it goes in circles (in all directions), then the theory would be falsified.

nope- all this would do is suggest that our universe [little u] was finite- the eternal/infinite Multiverse/Metaverse hypothesis [really an axiom] still remains and [as Spinoza demonstrated long ago- reiterated by Hegel] the existence of an eternal/infinite Universe [big U: the whole of Existence] is unavoidable given that there is Existence at all - this is what I am referring to as the "eternal/infinite nature of the Universe" [big U]

I personly have a feeling that universes are finite and curve back on themselves anyway- although ours is probably quintillions of light years in extent- the reason I feel this is becasue it seems more likely that finite spacetimes are imbedded in even larer finte structures/dimensional manifolds- just the hierarchy is infinite- not the members of the hierarchy-


Martin Rees explains these ideas all quite thouroughly: http://www.edge.org/3rd_culture/rees03/rees_index.html

___________________________

/:set\AI transmedia laboratories

http://setai-transmedia.com

 

[Haelfix]

The topology of the universe is an open question, though there are strong hints from COBE/WMAP that indeed it is topologically a flat plane.

By the universe here I mean the whole shebang, not just the visible part.

It could still be something like a torus, in which case presumably one day the theory would be falsifiable, but incidentally there are other potential ways to measure global topology.

The hope in astrophysics was that quantum gravity would someday isolate one solution that was at worst the simplest and at best unique, such that we wouldn't have to worry about waiting potentially billions of years before we could be confident about what we live in.

Alas, that's still work in progress.

Btw I agree the anthropic principle should be taken in its simplest form, ie a simple data point. The whole nonsense about statistical ensembles and what not strikes me as metaphysics and not something we should be spending our time worrying about.

We'll either figure it out one day, or we won't, but until we exhaust all avenues of science I don't plan on taking up philosophy or astrology just yet.

 

[Ontoplankton]

The point about the scientific community is they can get agreement by empirical tests.

they arent like theologians who split up into various parties and sects and schools of thought

The universe does not care about how we think social communities should work. It is under no obligation to provide us with ways to prove or disprove everything we would like to. If the most fundamental theory is one that makes no very specific predictions on what we will find (other than that we'll find a universe consistent with the existence of observers), then this is simply something we will have to accept. Anything else is just wishful thinking.

Of course, maybe this theory is wrong. If Smolin's black hole theory predicts specific things that the anthropic principle doesn't, then that counts in favor of it; but there are many things to take into account (such as: how plausible is his mechanism that generates a universe slightly different from ours? how strong is the evidence for eternal inflation?), and I have no way to judge all of these. Maybe Smolin's theory and the mono-vacuum versions of string theory will be falsified in the future; maybe in the future, the eternal-inflation-plus-anthropic-principle theory will the only one that predicts a universe with observers at all. In that case, we should accept it until we do find something better, and in the mean time, it should be taken seriously as a possibility.

But Onto, you have not yet exhibited anything weird about what Smolin says!

I exhibited a few weirdnesses in my first post in this thread.

I'm finding it difficult to criticize specific claims by Smolin, because I don't agree with the Popperian framework he places everything in. In fact, I can feel my brain shrinking as I think about falsificationism, right at this moment!

It's true that the anthropic scenario isn't falsifiable, but that doesn't mean it isn't testable in a more general sense. Any time a different theory predicts something specific about the universe not already implied by the existence of observers, that counts against the anthropic scenario; it makes it less plausible, just not impossible. Any theory that's consistent with any possible observation is unfalsifiable; there are more of such theories than you would expect. Smolin's black hole theory is one of them, because it has a varied multiverse where each universe has different laws. The difference between Smolin's theory and the anthropic scenario is that in Smolin's theory the worlds whose laws and constants are such that they don't allow for observers are "very rare" (though there are infinitely many of them!), rather than "common but empty anyway". I'm not sure that this should matter.

Anyway: IIRC Smolin calls his theory "falsifiable" even though it only makes probabilistic predictions (it's logically consistent with all sorts of physics, but some sorts of physics are more common because they produce more black holes), and at the same time calls the anthropic scenario "unfalsifiable" because it only makes probabilistic predictions (it's logically consistent with all sorts of physics, but some sorts of physics are more "typical" of the kind you would expect to see as an observer). The way to deal with probabilistic predictions is Bayesian probability theory. There are very difficult issues in how to deal with observational selection effects and with infinities in a Bayesian framework, but they're not the difficulties that Smolin talks about.

There's a whole literature on all this stuff, and it looks to me like Smolin hasn't read it.



IMHO, it all depends on whether Smolin's black hole claims hold up under further tests, and on how much more (or less) specific the region (in law-space) of black-hole-maximizing universes turns out to be compared to the region of observer-generating universes. It looks to me like Smolin may have a case for his theory, but his grounds for rejecting the alternative completely are wrong.

 

[jeff]

The Anthropic Principle = "Sorry, but we're kinda stuck for good ideas at the moment. Please check back later. Thanks."

 

[marcus]

The Anthropic Principle = "Sorry, but we're kinda stuck for good ideas at the moment. Please check back later. Thanks."

I agree with jeff.

 

[sol2]

The Anthropic Issue and the Flower Scheme

So who has last word?

Lubos said,

We have discussed these questions a lot on this board. If the number of
possibilities to create a Universe - including working cosmology - in the
correct theory *is* that huge, we will have to live with this fact. String
theorists don't agree yet whether the usage of the Anthropic Reasoning
will be necessary. Many of us hate it. But it is a logical possibility. At
any rate, as long as theoretical physics exists as a field, the scholars
in it will study something. Because they have no new experiments, they
must study more or less pure theory. String theory remains the most
promising game in town, perhaps the only game in town. This might
hypothetically change - but only if someone found something equally (or
more) interesting. It cannot change by political speaches without
scientific content, even if the speaker is as famous as Roger Penrose.

https://www.physicsforums.com/showthread.php?p=271882#post271882

So you can see, you have to be smarter then Edward Witten, and apparently you Marcus and Jeff are not. Cheez, that Lubos guy is sure not very nice. He think's he's tuff guy

Most string theorists are also too
nice - perhaps except for me- and therefore they won't comment on
declines of Roger Penrose although there would certainly be a lot of stuff
to discuss.

http://web.uvic.ca/~jtwong/T-Huniverse.jpg

I think the issue has become somewhat confusing when you think the universe came from a pea So where did the Pea come from?

And then he has the nerve to comment on the GRanium and Daisey's as Tulips! Not very original I think although they do belong to the class of the flower children. Maybe we can work the image of the tulip into Hawking's as a good visualization of the Instanton? Or even the lotus flower, as a symbol of the "emergent realites," deep from our subconscious level

> String theory has had a kind of tulip-mania fad or craze and now seems
> to be in decline.

Well, we've heard such things since the middle 1980s at least. It is
certainly a longer-lasting fad than any other fad in the history of
humankind. ;-)LM

Let's heard from you now Lubos-the tuff guy. I know thorny Jeff(the rose) can give you a run for your money


So now being lead into this fantasy:

Sol said:Would twenty mattresses help Alice, and how complex can each mattress remove the thinking from the pea of concern

http://superstringtheory.com/forum/dualboard/messages11/44.html

Fictional Alice was a http://superstringtheory.com/forum/dualboard/messages11/100.html :) Mathematicians tire easily becoming lost in the abstract theoretical world, so often times like Lewis Carroll, they create this new found fantasy to help see the world in a different way? Break the bonds of abstractness, and loose themselves in this world of fantasy.

What you don't like Penroses tessellations or Escher's interconnecting lizards?

During the later half of the 1950’s, Maurits Cornelius Escher received a letter from Lionel and Roger Penrose. This letter consisted of a report by the father and son team that focused on impossible figures. By this time, Escher had begun exploring impossible worlds. He had recently produced the lithograph Belvedere based on the “rib-cube,” an impossible cuboid named by Escher (Teuber 161). However, the letter by the Penroses, which would later appear in the British Journal of Psychology, enlightened Escher to two new impossible objects; the Penrose triangle and the Penrose stairs. With these figures, Escher went on to create further impossible worlds that break the laws of three-dimensional space, mystify one’s mind, and give a window to the artist heart.

In order to understand how Escher used impossible figures to create impossible worlds, impossible figures must be clearly defined. In his article Escher’s Impossible Figure Prints in a New Context, Ernst Bruno gives a thorough description of the thought process one goes through upon seeing an impossible figure. Bruno’s account can be summed up to produce a concise definition of an impossible figure; a definite figure with conflicting depth cues.

http://www2.bc.edu/~schiavop/escher.html

 

[marcus]

Hi Sol, tho often perceptive you may have a misconception here. If you could get Witten and Motl and Smolin to sit down just to talk about the effect on String theory research
of Susskind invoking multiple universes and resorting to athropery

(not to quarrel about other issues or discuss the merits of Loop or anything else, but just to assess whether AP has had a good effect)

what do you think? I don't want to put words in their mouths, but I think you should realize that they might agree in condemning Susskind's line and the AP, or deploring it's taking String theory in an unscientific direction.

Witten has expressed disapproval of resorting to AP
Motl (who may tend to follow Witten's lead in some matters) has
strongly condemned AP
Incidentally Jeff (who may tend to follow Motl's lead on key issues, or have come to similar positions independently) is here in solidarity with Witten and Motl.
Incidentally BTW (tho small fry outsider to string) I am in agreement with these people----Susskind's noisy invocation of AP, which has damaged the perceived integrity of String research, is causing distraction and a waste of intellectual resources.
Smolin would agree I believe.

Your post seems to suggest (if I read your symbolic and ornamented language correctly---which can be both a challenge and a pleasure)
that you expect disagreement and see a possibility for debate.

Of course I can't speak definitely for Jeff or any of those others but I strongly suspect that if you could get Witten, Motl and Smolin to discuss just that one issue they would be in hearty agreement-----contrary to what you seem to expect.

Let's not manufacture disagreement where there is none, sol

 

[sol2]

Hi Sol, tho often perceptive you may have a misconception here. If you could get Witten and Motl and Smolin to sit down just to talk about the effect on String theory research
of Susskind invoking multiple universes and resorting to athropery

(not to quarrel about other issues or discuss the merits of Loop or anything else, but just to assess whether AP has had a good effect)

what do you think? I don't want to put words in their mouths, but I think you should realize that they might agree in condemning Susskind's line and the AP, or deploring it's taking String theory in an unscientific direction.

Witten has expressed disapproval of resorting to AP
Motl (who may tend to follow Witten's lead in some matters) has
strongly condemned AP
Incidentally Jeff (who may tend to follow Motl's lead on key issues, or have come to similar positions independently) is here in solidarity with Witten and Motl.
Incidentally BTW (tho small fry outsider to string) I am in agreement with these people----Susskind's noisy invocation of AP, which has damaged the perceived integrity of String research, is causing distraction and a waste of intellectual resources.
Smolin would agree I believe.

Your post seems to suggest (if I read your symbolic and ornamented language correctly---which can be both a challenge and a pleasure)
that you expect disagreement and see a possibility for debate.

Of course I can't speak definitely for Jeff or any of those others but I strongly suspect that if you could get Witten, Motl and Smolin to discuss just that one issue they would be in hearty agreement-----contrary to what you seem to expect.

Let's not manufacture disagreement where there is none, sol

Marcus,

I like to create some humour as well and it should be taken in that context.

Do you really think I think any of these guys as tuff? I am challenging the group(flower children) per say that it has all been said and done. Do you really think they could sit down and agree? I know what they choose to believe

I also am speaking to Lubos on his position with Penrose. Imagine those math minds:)

 

[Ontoplankton]

If you could get Witten and Motl and Smolin to sit down just to talk about the effect on String theory research
of Susskind invoking multiple universes and resorting to athropery

I don't think physicists should be going down the path of "you must not think or talk about that, because it would be harmful to our cause". I prefer if they just tell me what they think are the most likely possibilities for what reality is like, rather than worry about taboos. If people like Gross and Witten and Smolin think no anthropic explanation will be needed, that's great. If people like Susskind think string theory leads to an anthropic scenario, that's also great.

 

[jeff]

What started this whole thing was the astonishing discovery that, contrary to all previous thinking, our universe is undergoing accelerated expansion.

This can be considered in the framework of GR as indicating something like a de sitter cosmology. However, the moduli space of string vacua don't include spatially compact cosmologies (consistent with the basic holographic nature of any correct theory of quantum gravity, the only true observable is the S-matrix whose inputs and outputs lie at spatial infinity and there's no such thing in spatially compact cosmologies). There are then two ways to look at this.

One is that we have to somehow find a way of bringing de sitter into strings and it was this attitude that led to the current debate. Specifically, they looked for metastable (that is stable for long periods of time) de sitter spacetime among all vacua, not just string vacua, with the very justifiable belief that string theory would still have relevance in such situations. Unfortunately, they found many such vacua but with no closed mathematical-physical principle to choose among them. Hence the invocation of the anthropic principle. Of course, it's possible that there is a way to sneak de sitter into string theory, but we just don't yet know how.

The other way to look at it is that the accelerating expansion is due to something that we don't yet understand and doesn't require de sitter.

The question is then whether we understand strings well enough to settle for the anthropic principle, and the answer is clearly no. From this standpoint, it's premature to be worrying too much about the anthropic principle. More generally, our understanding of strings is so primitive that we can't honestly conclude that any of it's current problems are fatal. Striking oil often requires we drill mighty deep holes and we've got a whole lot more drilling to do before we can give up on what has proven to be such a rich and self-consistent well-spring of deep ideas that is still our only known genuine quantum theory of gravity.

 

[selfAdjoint]

This was a very informative contribution. Thanks Jeff. I had wondered why the multiple solutions probloem, which I remember being discussed several years ago, had suddenly become such a hot topic.

 

[setAI]

more lenny vs lee action!


http://www.edge.org/3rd_culture/smolin_susskind04/smolin_susskind.html

 

[marcus]

more lenny vs lee action!


http://www.edge.org/3rd_culture/smolin_susskind04/smolin_susskind.html

setAI thanks for posting this!
a big reason I (and I would guess others) come to PF is to
get links to new really interesting stuff.

Smolin said something new in the final letter section, that caught my attention.
He referred to what I think is an important paper of Gambini Porto Pullin
about how using a realistic clock (instead of a nonexistent ideal clock)
can resolve the black hole information paradox.
(information decoheres by itself before the hole evaporates)

the two final letters start 2/5 of the way down the page, printed side by side in parallel columns.

If you go down to the 2/3 mark of the page----a ways down in the
final letters----and look in Smolin's column you will see this paragraph:

---quote---
"A second point is that there is good reason to believe that in quantum gravity information accessible to local observers decoheres in any case, because of the lack of an ideal clock. In particle physics time is treated in an ideal manner and the clock is assumed to be outside of the quantum system studied. But when we apply quantum physics to the universe as a whole we cannot assume this: the clock must be part of the system studied. As pointed out independently by Milburn [e] and by Gambini, Porto and Pullin [f], this has consequences for the issue of loss of information. The reason is that quantum mechanical uncertainties come into the reading of the clock — so we cannot know exactly how much physical time is associated with the motion of the clock's hands. So if we ask what the quantum state is when the clock reads a certain time, there will be additional statistical uncertainties which grow with time. (In spite of this, energy and probability are both conserved.) But, as shown by Gambini, Porto and Pullin, even using the best possible clock, these uncertainties will dominate over any loss of information trapped in a black hole. This means that even if information is lost in black hole evaporation, no one could do an experiment with a real physical clock that could show it."
---endquote---

where you see footnote reference [f] that is to this neat paper.
It came out in June before the big fuss over Hawking GR17 talk in July.
In my view it probably made the hooraw about Hawking superfluous.
I am glad Smolin is recognizing and citing this work. Jorge Pullin
occasionally visits here at PF and also puts out Matters of Gravity newsletter. I should get a link or two

 

[sol2]

I read this first thing this morning when reading in sci.physics the link (Should of read Peter Woits, Not Even Wrong Blog. Sorry Peter.

What I took with me from that article is the perception that is embedded in the debate about black holes.

That raises the question of what exactly is a black hole? One of the deepest lessons that we have learned over the past decade is that there is no fundamental difference between elementary particles and black holes. As repeatedly emphasized by 't Hooft [10][11][12], black holes are the natural extension of the elementary particle spectrum. This is especially clear in string theory where black holes are simply highly excited string states. Does that mean that we should count every particle as a black hole?

Smolin's theory requires not only that black hole singularities bounce but that the parameters such as the cosmological constant suffer only very small changes at the bounce. This I find not credible for a number of reasons. The discretuum of string theory does indeed allow a very dense spectrum of cosmological constants but neighboring vacua on the landscape do not generally have close values of the vacuum energy. A valley is typically surrounded by high mountains, and neighboring valleys are not expected to have similar energies.

http://www.edge.org/3rd_culture/smolin_susskind04/smolin_susskind.html

The word Susskind uses as discretuum(in bold) in regards to strings is most troubling. Maybe someone can speak to that?


Can Consciousness be truly expressed in the geometrical design( this has yet to be discerned), although I have been working on it as you can tell in liminocentric structures.


This might be found different from Smolins, based on their diffrent views and the different in the choice of geometry? The SRian approach and revisions?

You cannot speak about the background dependence unless you are immersed in it? And of course this requires a different frame? See http://wc0.worldcrossing.com/WebX?14@84.f0BIcWLAyal.19@.1ddf4a5f/99 for consideration about those frames?

 

[Ontoplankton]

Now http://www.edge.org/discourse/anthropic.html#myhrvold weighs in with yet another confused piece on the anthropic principle. His definitions of the "weak anthropic principle" and "strong anthropic principle" are around the tenth completely different variant that I've seen.

He questions "what value there is in not being surprised", but isn't the whole point to have theories under which our observations are unsurprising -- isn't that what an explanation is?

 

[marcus]

another word for it

Tom Banks has just posted 0408260
the first lines of the introduction go:


"Introduction
The hypothesis of Cosmological SUSY Breaking[1] (CSB) correlates the gravitino mass, m_3/2 with the cosmological constant, according to the formula

F_G \sim m_{3/2}M_P \sim \Lambda^{1/4}M_P . (1.1)

Lambda is viewed as a discrete, tunable parameter (perhaps determined in the real world by galactothropic considerations), and the limiting model with vanishing Lambda is assumed to preserve exact N = 1, d = 4 super-Poincare invariance and..."

then again on page 3 he goes:

"...This gives rise to a gravitino mass of order 10^-3 eV. The formula for the mass scales with the power of Lambda predicted in [2]. The value of w(0), which is a number of order 1, must be fine tuned to an accuracy
\inline{\frac{\Lambda^{1/2}}{M_P^2}} in order to produce the correct value, Lambda, for the value of the effective potential at its minimum. Lambda is a fundamental input parameter in CSB, rather than a calculable low energy effective parameter, so this fine tuning is philosophically unexceptional. If one wishes, one can determine the correct value of this parameter in the real world, by applying the galactothropic principle of Weinberg[5], rather than simply fitting more recent cosmological data..."

Lot of stuff going down around Lambda these days. For Smolin it seems to be a kind of pre-stressed curvature in space and a fundamental constant that applies to LQG, mond, etc.
for Banks it seems to be the "gravitino" mass
Banks does seem to respect Smolin's point that what Weinberg did was NOT
an application of the anthopic principle because it derives constraints on the value of Lambda by theorizing about galaxy-formation.
Nothing said about multiple universes or conscious life or all that jazz.
Just that whatever it is Lambda couldn't be too big or it would blow galaxies apart before they could form. So you could estimate an upper bound on it, from existence of galaxies.
Smolin made that point in "Scientific Alternatives to the Anthropic Principle"
the paper that yanked Leonard Susskind's chain to a considerable degree.
So now, for whatever reason, Tom Banks has the consideration to
call Weinberg's reasoning galactothropic rather than anthropic.
Clearly an idea whose time has come

 

[Ontoplankton]

This is why people distinguish between the "weak anthropic principle" and the "strong anthropic principle". The weak anthropic principle says that since we exist (or: since galaxies exist), we should predict the value of the cosmological constant isn't too far from zero. Whether we should call this "anthropic" at all is a question of terminology; maybe we shouldn't, because we're reasoning from the existence of galaxies, not from the existence of humans.

So far, so good. But there also exists a strong anthropic principle. The strong anthropic principle says that the fact that a sufficiently low cosmological constant is necessary for the existence of observers explains that our universe is that way, e.g. because there is an ensemble of universes over which the cosmological constant varies, and the ones where it's too high don't contain any people. So if it's about explanations of the cosmological constant, you do have to talk about observers instead of galaxies; it makes no sense to say that we (a priori) have to observe a small cosmological constant because we have to observe galaxies, unless it's because galaxies are necessary to have observers. The existence of galaxies doesn't explain why we observe a small cosmological constant, just because we live in a universe with galaxies; saying this would be like saying that the existence of cows explains why there is gravity, because we observe cows, and for there to be cows, there has to be gravity.

It's very easy to get confused about these things, and I think it's happened to many people.

Also, in the debate at Edge, I see Susskind saying this:

In particular Weinberg's prediction that if the anthropic principle is true, then the cosmological constant should not be exactly zero, is very similar to the example I just invented.

So, as I understand it (though I haven't looked at what exactly Weinberg did), Weinberg didn't just predict the cosmological constant to be within certain bounds; he predicted it to be nonzero, and not extremely close to zero.