On my top ten list there is the question whether the parameters of the standard model (SM) can be derived from within a yet-to-be-found theory of everything (TOE). And if so, how. Can we make sense out of this collection of numbers? Lately, this question has been dominated by a topic I still can't make any sense out of: the Anthropic Principle (AP).
In this post I want to share some of my thoughts on the AP, and its sense or non-sense. You might also want to read my earlier post The Principle of Finite Imagination (alias: The Liver Post).
I want to state at the beginning that I don't want to discuss whether life on earth is 'intelligent' or 'civilized', so you might want to replace 'life' with 'intelligent life' or 'civilization' if you feel like it.
Below you find my thoughts on the following four statements that I have encountered:
- A: The conditions we observe in our universe are such that they allow the existence of life. (Or, equivalently: If the conditions were such that they didn't allow the existence of life, we wouldn't be here to observe them.)
- B: If we assume that the conditions are according to some random distribution function then we live in a typical sample, and we are typical for the universe we life in.
- C: The conditions we observe in our universe are optimal for the existence of life.
- D: The conditions we observe in our universe are optimal in some other sense.
A
Is usually called the weak Anthropic Principle (AP). It's scientific content has been debated over and over again, see e.g. Lee Smolin's paper and the following argument with Leonard Susskind. The AP is not a theory, and I honestly have no idea what the scientific status of 'principle' is supposed to be. I think the main issue for the physicist is whether or not the AP allows to make predictions, and whether it is scientifically useful. Or at least this should be the main issue for us.
Without any doubt, A is a true statement. That means not only it can't be falsified: it can't be false. But this does not mean it can't also be useful. It's a device one can use to draw conclusions. And indeed, one can use it to derive constraints on observables. However, this is no more a scientific theory than the use of mathematically true statements.
E.g. consider you compute a prediction for the lifetime of muons at relativistic speed with Lorentz-transformations and use cosh2 - sinh2 = 1. If your prediction is correct, you'd not claim that this is due to the use of a trigonometric identity. Instead, the agreement of your computation with the observed value it a confirmation that Special Relativity is a successful description of reality.
Likewise with Weinberg's bound on the cosmological constant. In a nutshell the argument is: when the cosmological constant was larger than some value, then galaxies would not have formed and we would not be here. Deriving this bound thereby using A, and finding it fulfilled by the observed value is a confirmation of having properly used a sensible theory for gravity and an appropriate model for density fluctuations. If the derived bound would have turned out not to be fulfilled, we'd not have concluded that A is wrong. Instead, we'd have concluded there is something wrong with our understanding of structure formation.
So, A can be used in the context of a theory or a model to make predictions, just that any conclusions drawn from this are not about A, but about the theory or the model.
B
Is also called the Principle of Mediocrity. For me, one of two crucial question here is the distribution of the parameters. This has to be given (preferably motivated, maybe just postulated) through some kind of a model. From this, one can then find out the most probable configurations. Since we are typical, we belong to one of these. If the parameters in this configuration do agree with our observations we could conclude that the distribution of the random parameters was in accordance with the expectation B that we live in a typical universe.
However, the randomness of the distribution always leaves a sneaky way out. If we measure some parameters, then the distribution of parameters as evaluated from the model will agree with some probability. How small do we allow this probability to be still acceptable, i.e. typical? Or, how natural is natural? Let's say we set this acceptable probability to a value X. Then, we'd have to discard the model leading to the distribution when the observed values would have a smaller probability.
One can do this. This is basically a search for random distributions that have maxima not at the observed values, but sufficiently close around them to be in accordance to our acceptance limit X.
A second huge problem of this approach which I see is obviously what it means for the universe that we are 'typical'. What of our universe has to be typical, and at which stage of the evolution does it have to be typical? I have no idea how the notion of being typical could be put on solid feet.
So, in my eyes B is the construction of models within which the observed parameters of the SM have a certain probability. The higher this probability, the better the model. (Hopefully, the model itself has less free parameters than the SM itself). The central statement of being typical is very ill defined and vague.
Approaches to describe nature like this were essentially the reason why I left Heavy Ion Physics (replace 'acceptable probability' with 'errorbars').
C
Is a more sophisticated version of B, where being typical is replaced with being optimal. It suffers from the same problem of dealing with a very vague quantity, that is the 'optimalness for the existence of life'.
To underlay this with a physical approach, what we really want is some function of these parameters that we aim to predict -- a function which is optimal for the actually observed values. For the case C, this function would have to be
Optimalness-for-Life(Parameters of the SM)
Applying a variational principle to this 'function' seems to be hopeless, but what one can do instead is tuning the variables (parameters of SM) up and down to see whether the optimalness decreases. I.e. the poor man's way to determining a minimum. This is essentially what has been done in a huge amount of examples, and results typically in statements like: When the size of my cellphone was just 2% smaller, then life would not be possible.
Despite the fact that this way one can only check for local minima, and that one can not really draw conclusions when keeping some parameters fixed and varying only a few, imo the largest problem is the absence of a reasonable definition of Optimalness-for-Life. There is way too much ambiguity attached to it. What can we possibly learn from this? Only that - assuming we live in a universe optimal for life - our idea of being optimal is not in disagreement with observation.
So, in my eyes C is an improvement over B but the central point of 'being optimal for life' is too vague to allow sensible insights into the secrets of nature.
D
Can abstractly be formulated as: there is some function of the parameters to be determined that is optimal for the observed values. The question then is what this function is. Apparently, the universe is not such that it optimizes the amount of US$ on my bank account. Too bad.
Lee Smolin proposes that the number of black holes could be such a function (Cosmological Natural Selection), whose value is maximized for our universe. Though the function Number-of-black-holes(parameters of the SM + LambdaCDM) itself is unknown, at least it's a well defined quantity. Here again, one can test whether we are in a local extremum by tuning around parameters and estimate the effect. It seems, the number of black holes is not such a bad guess (to me this is really surprising.)
Imo, it's in this regard not even important whether or not all the universes that belong to the non-optimal parameters actually 'really' exist. When I make a variation over the metric in GR to find the optimal and realized configuration, I don't think of the other ones as being alternative universes. However, in Lee's scenario the other universes do 'really' exist, and the claim is then that we are likely to live in a universe where the number of black holes is as large as possible. This then has the additional virtue of providing a reason why the number of black holes is the function to be extremal (for further details, see hep-th/0407213 or The Life of the Cosmos) .
One way or the other, D comes down to the question whether there is a function that is optimized when the parameters of the SM have the values we observe. And which in addition to reproducing known number allows us to learn something new (i.e. make at least one falsifiable prediction).
But then, the question lying at hand is whether this function can be derived from the fundamental principles of the TOE. It might be that this is not the case, but that e.g. the initial conditions play a central role. An example that has been used elsewhere (sorry, forgot where) are the orbits of planets in the solar system, which have historically been thought to arise from some symmetric construction. Today we'd say the orbits of the planets follow when we have given the initial stress-energy distribution, and the quantity to be optimised is the Lagrangian of GR plus that of the matter field. We would not expect the orbits of the planets to be predictable from the SM of particle physics plus GR. Or from putting Dodecahedrons inside Icosahedrons (see Platonic Solids).
But even if the function to be optimized can be derived from the TOE, in practice it might not be a useful way to deal with it in the full context. Just like we don't explain liver growth starting from the SM of particle physics, I find it a reasonable expectation that a macroscopic description of our universe might be more useful to determine the parameters of the SM.
However, I'd say our insights about a possible TOE are not yet deep enough to let us conclude that not even some of the parameters in the SM might be explained within such a fundamental theory.
TAGS: SCIENCE, PHYSICS, ANTHROPIC PRINCIPLE
Hi Bee, an easy to read step by step review of the Anthopic Principle.
ReplyDeleteIf it helps you grapple with anything, nothing is much more than explaining what is. ie:
discovering that there is oxigen in the air and we need breathe oxigen to exist (in our present form) are only defining in words, chemical formula or even maths if you want to measure how lung you can hold your breath under water.
These steps, cannot and do not ultimately define why, things are thus - they just explain their relevance to us the observers.
Now you can theorize that we can change the way we breeze to go deep sea diving. Have you seen the film Abyss where you sort of drown, get past the reflex action and start breathing like a fish without gills so to speak.
So trying to define the Universe, the Cosmos or even physical conditions are only parts of the whole.
So you got a nice mention at cosmic variance.
Laters Q
A surprisingly reasonable treatment.
ReplyDeleteA is a tautology that may be used to argue indirectly but that can't be used as a microscopic explanation of anything we observe.
C and probably D are wrong. There are many suboptimal things everywhere around. Life is never quite optimal and it does not have to be optimal. The only thing that is extremized is the overall action, and this is only true in the classical limit. ;-) Moreover, I am not Chinese and neither of us is insect.
This is why B is probably wrong, too. We're not generic either. If the laws of physics tell you that an observed fact should be very unlikely, then we can be suspicious about the existing form of the natural laws. However, for things that we only observe once, we don't have the repeatability of science that is necessary to assign hypotheses ever smaller or ever bigger probabilities.
If we only see certain things once, we can always say that an unlikely outcome was a result of good luck. If it ever turns out that there is a 0.0001% probability that a galaxy in the Universe will start life before the stars turn off, the number 0.0001% just measures how lucky we were in this respect. There is no need for this number to be close to 100% and the same thing holds for other numbers, too.
It may be OK to prefer a hypothesis that makes the observed things more likely over a hypothesis that makes them less likely, but if there is only one competing theory, there exists no fundamental law that would determine how likely the observed things should be according to this theory.
To summarize, only A can be used to make justifiable conclusions - but even these conclusions cannot be viewed as a fundamental understanding of a feature of the real world. And of course, I agree that B, in order to be well-defined, must be supplemented with a measure or a probability distribution, and the confidence level that the right distribution is a uniform measure for every individual vacuum is comparable to the confidence level that the relevant distribution is any other function.
Best
Lubos
The way I look at A is that its a statement of selection effects. We can't be in a universe where life couldn't form, so what we can see is in some sense constrained.
ReplyDeleteI'd agree with Lumo that B, C and D are probably wrong.
Optimal - most desirable possible under a restriction expressed or implied
ReplyDeleteI don't see how the ecobalanced nature of the anthropic coincidences isn't optimized for life, (and/or black holes... like Lee Smolin said).
For random enjoyment: There is a famous and funny example of combining "We are here" and statistical reasoning, called the Doomsday Argument which goes like this:
ReplyDeleteMankinds population is exponentially increasing until a catastrophe. Therefore most people live near to the catastrophe, therefore it is unlikely to live far from the catastrophe, therefore the catastrophe is just around the corner!
therefore the catastrophe is just around the corner!
ReplyDeleteRIGHT! They call it Highway 101.
There is an "unknown and unfunny" prediction that falls from combining evolutionary theory with anthropic specialness that goes something like this:
ReplyDeleteA true *special* anthropic constraint on the forces of the universe will necessarily include a reciprocal connection to the human evolutionary process, which indicates that there exists a mechanism that enables the universe to "leap" to "higher"/more efficient configuration of the same basic structure.
Which explains why the forces can't be unified, while defining the ToE... the next universe will be even more-"flat" than this one is!
But then everyone would be out of work and as Lawrence Krauss noted... we can't have that.
Not sure how this started or where it's going, but here goes ...
ReplyDeleteWithout Man & Woman, the discussion ends. If we are not, then we are not here or in any other universe, it really does not matter whether the universe exists or is a figment of our imagination, which it cannot be if we are not. So everything is relevant to the observers us, man & woman. It doesn't mean it is everything that 'exists' since clearly we are only aware of what we know. Thus we theorize on the possibilities of what may or may not be. To some it is fantasy or fiction, to others it is science fiction, and in the linear time line, some things which are science fiction become fact - ie: mobile phones & the internet.
Did they exist before we created them? - No
Could we have created them, if they could not exist? - No
Do microstates at subatomic level represent blackholes in space? hmmm
Do blackholes exist in space? seems almost a given
Are singularities the same as blackholes? Not in my dictionary.
Which information are you losing Bee? Where does the lost info or lost mail go? Where do lost UPS parcels end up? I don't mean misplaced ones, I mean lost as in gone, fallen off the back of the truck gone.
Where did yesterday go Bee?
Where did last year go?
Is that information loss?
Dear Lubos,
ReplyDeletethanks for your comment. Surprisingly, I mostly agree with you.
D is the only version I could attribute some scientific value to, though I don't think it is relevant for the question of parameters in the SM. However, I tend to believe that the parameters of LambdaQCD (e.g. Lambda itself) will turn out to be caused by macroscopic phenomena, and do not directly follow from the fundamental theory.
Dear island,
I don't see how the ecobalanced nature of the anthropic coincidences isn't optimized for life, (and/or black holes... like Lee Smolin said).
There is a big difference between being 'optimal for life' and being optimal in the sense of producing the largest number of black holes. 'Optimal for life' is not a scientifically well defined expression. If you think so, please explain me what it means.
Does it mean there is as much life as possible in our universe? Is this so? What kind of life? Does some version of life count more than others? Should life be as complex as possible? Is more complexity more optimal? Or should it be as reproductive as possible? And again: is this so? Does this refer to an average value over all times? Or should there be as much life as possible at some specific time? And so on. Being 'optimal for life' sounds nice, but is in my opinion not a useful scientific statement.
If you see that 'the ecobalanced
nature of the anthropic coincidences' is optimized for life, then what exactly do you mean with that?
Best, B.
Bee, I'm not the first person to notice that the anthropic coincidences, which are all entirely necessary to life as we know it, are "ecobalanced" by the "goldilocks" facet of the AP.
ReplyDeleteI'm also not the first person to notice that this physics cannot be restricted from including every galaxy that evolved under the same conditions as we did, in terms of time and "location".
Not too big, not too small, not too old, not too new... etc... every galaxy that exists in balance is predicted to have a greater likelihood for intelligent life for the reasons that I've given.
Optimization also occurs when an entity arises that requires less energy to isolated enough energy to make matter/antimatter pairs than it does for black holes or supernovae to do the same thing, so intelligent life will be as common along the previously described region of space as the practical need for it demands.
People have no trouble understanding that teeth arise from the practical need for them, but there is a sadly widespread lack of imagination when humans become the teeth that arise as a mechanism for evolution.
Hi Bee, for moreon the Susskind Smolin debate:
ReplyDeletehttp://quasar9.blogspot.com/2006/06/4qs-to-leonard-susskind.html
Hi Cynthia!
How about all 'possible' universes converge in this one Universe we are in - the pocket universes are the dimensions in which other critters (flies, ants, butterflies) live on this planet we call Our Planet or Earth. As for aliens, no need to go looking for other universes with different physical laws - what would a being living on Venus or Mars look like. I don't mean human's living in an artificial environment suitable for humans on Venus or Mars, I mean beings living under the physical laws which exist on Venus or Mars - or the Moon even.
Dear island,
ReplyDeleteNot too big, not too small, not too old, not too new... etc... every galaxy that exists in balance is predicted to have a greater likelihood for intelligent life for the reasons that I've given.
Have re-read your post. I neither found any reasons you have given, nor have you explained what a greater likelihood for intelligent life means - see my previous comment.
intelligent life will be as common along the previously described region of space as the practical need for it demands.
I take it you are claiming that the universe needs intelligent life for it's existence?
People have no trouble understanding that teeth arise from the practical need for them, but there is a sadly widespread lack of imagination when humans become the teeth that arise as a mechanism for evolution.
There is also a sadly widespread lack of imagination when it comes to explain the parameters of the SM from a to-be-found TOE.
Regarding your opinion that intelligent life in exactly the way we encounter it is a practical need for the universe to be as it is, I don't see how it could be possible to use this rather speculative claim to explain anything.
Best,
B.
Let me just add to your example with the orbits of the planets that your 'explanation' (in terms of the Lagrangian) does not explain the to some extend exact simple rational ratios between the radii of the different planets while the picture with the Platonic solids does exactly this.
ReplyDeleteHowever, there is also a more natural explanation in terms of long time stability (Urschleim wouldn't have observed anything) of the graviational N-body problem as anything in between has been kicked out of the solar system long long ago.
Q,
ReplyDeleteIt appears that the first part of your comment is expressing a more extreme version of the "B" statement. More specifically, the Principle of Mediocrity is the foundation for the "B" statement. Therefore, mediocrity taken to the utmost extreme translates into a universe in a stagnant heat-death. On a more upbeat note, the Universe can overcome this classical heat-death via low entropy fluctuations emerging from the quantum realm.
The last part of your comment conveys that physical laws are different in different regions of the Universe. However, it is the uniformity in the physical laws of the Universe which defines the Universe as a universe. In other words, the Copernican Principle doubtlessly refutes this idea of regional variation within the Laws of Nature. Perhaps I'm hopelessly an old-fashioned thinker in the Cosmos...
Best regards,
Cynthia
your 'explanation' (in terms of the Lagrangian) does not explain the to some extend exact simple rational ratios between the radii of the different planets while the picture with the Platonic solids does exactly this.
ReplyDeleteThe point is that there might just not be anything to explain. If you take enough numbers and multiply, add, exponentiate them around you will always be able to produce some 'surprising' coincidences.
Best, B.
Hi Cynthia,
ReplyDeleteTherefore, mediocrity taken to the utmost extreme translates into a universe in a stagnant heat-death.
Well, I don't think that is the intention of the principle. As used e.g. by Garriga and Vilenkin (astro-ph/0210358, p. 2) it says
"[...] the mediocrity principle, according to which our civilization is typical in the ensemble of all civilisations in the universe."
That doesn't mean though that all protons in the universe should move equally random.
Best, B.
Hello Bee,
ReplyDeleteMy point: Mediocrity is not a "black and white" issue. Doubtlessly, there is a "spectrum of grays" to mediocrity. I was simply reflecting upon the extreme end of the mediocrity spectrum: the extreme end of fixed randomness, in turn, the heat-death. Obviously, the universe does not exemplify this extreme end of the mediocrity spectrum. Otherwise, we -as sentient beings- would not be engaging in this discussion on mediocrity.;-)
Even if the Universe evolved into this extreme form of mediocrity (in the form of a heat-death), a low-entropy fluctuation from the quantum realm is likely to emerge offsetting this fixed randomness (this heat-death).
The only reason I brought up this extreme version of mediocrity is because Q was implying of its existence: "all possible universes converge [into] one". In other words, Q was suggesting that the Universe might be a kind of perfectly mixed, melting pot. Therefore, my only intention was to refute the existence of this extreme form of mediocrity.
Best regards,
Cynthia, far be it for me to wish to disagree with you, however let us not call this dancing out of step, but as in ice-skating I propelling you up into the air, you pirouetting gracefully triple twirl and landing on your feet.
ReplyDelete"all possible universes converge [into] one".
Subtle, but You changed or substituted [in] for [into]
Hi Cynthia!
How about all 'possible' universes converge in this one Universe we are in
I know Women are from Venus and Men are from Mars, but literally speaking whichever planet you choose, different physical laws exist in those other planets, to the one we make contact in human form.
Even on the moon You'd need to create an artifial earth environment for man (or woman) to be able to exist in human form.
Or was the moon landing really a staged hollywood b-movie?
Dear Q,
ReplyDeleteI'm most captivated by your strong anthropic description of our solar system.;-)
Best wishes,
Hi Cynthia,
ReplyDeleteI see, sorry for the misunderstanding. The one question is to what 'things' in the universe 'mediocrity' is applied to - certainly not on an elementary particle level. But then the other question was still what mediocrity means. I.e. a random distribution for momenta of the 'mediocre things' is not going to do it.
I guess for me this whole issue is much too messy to get some sensible information out of it.
Hi Quasar,
thanks for the link. I read something different out of your remark above, more like: we might be surrounded by tiny random non-SM bubbles, and the longer the universe lives the more of them pop up, until eventually everything is maximally mixed up.
I was just wondering whether my head has turned into a specifically non-SM bubble. Best,
B.
"It's life, Jim, but not as we know it."
ReplyDelete... Weinberg's bound doesn't apply to *us* in particular, but to any form of life that needs gravitationally bound systems of a given size to live in. That seems a lot more robust than talking about oxygen or atoms or protons.
The result of applying 'anthropic considerations' to lambda is quantitatively not so good since we could have a larger cosmological constant and live in an isolated small galaxy surrounded by a sea of vacuum energy. It becomes even worse if you allow to vary the size of initial density perturbations along with the cosmological constant.
The only real success is that it would lead us to believe that lambda is not unmeasurably small - which turned out to be correct.
Well, it is also a success in that it is not clearly nonsensical, which seems to be quite an achievement in this subject.
Bee said:
ReplyDeleteHave re-read your post. I neither found any reasons you have given, nor have you explained what a greater likelihood for intelligent life means - see my previous comment.
And yet, I had just finished telling you that there is a greater liklihood that life will be found in galaxies that exist in the balance, due to the goldilocks constraint, than is the expectation for finding life in galaxies that do not fit this criterion.
This also removes your rationale for not including life with black holes, so this combines numbers 3 and 4, but did you recognize that either?... nope.
Bee said:
I take it you are claiming that the universe needs intelligent life for it's existence?
I've already explained all of this to you in the past, so the only thing left to do is to refer you to the physics that fixes Dirac's hole theory, his Large Numbers Hypothesis, (where Dicke got his anthropic coincidence from), thereby completing and clarifying the ENTROPIC anthropic principle.
http://www.lns.cornell.edu/spr/2006-02/msg0073320.html
http://www.lns.cornell.edu/spr/2006-03/msg0073465.html
There is also a sadly widespread lack of imagination when it comes to explain the parameters of the SM from a to-be-found TOE.
See the above physics, but the real cop-out on causality comes when scientists flat REFUSE to look for good reasons for why humans might be the explaination that you're looking for.
Regarding your opinion that intelligent life in exactly the way we encounter it is a practical need for the universe to be as it is, I don't see how it could be possible to use this rather speculative claim to explain anything.
No, it's not simply speculative when it falls most naturally from theory, given only anthropic specialness...
A true *special* anthropic constraint on the forces of the universe will necessarily include a reciprocal connection to the human evolutionary process, which indicates that there exists a mechanism that enables the universe to "leap" to "higher"/more efficient configuration of the same basic structure.
Which explains why the forces can't be unified, while defining the ToE... the next universe will be even more-"flat" than this one is!
I gotta go find a different wall to talk to.
Dear island,
ReplyDeletespeaking of talking to a wall...
And yet, I had just finished telling you that there is a greater liklihood that life will be found in galaxies that exist in the balance, due to the goldilocks constraint, than is the expectation for finding life in galaxies that do not fit this criterion.
I repeat again, could you please clarify what you mean with greater likelihood that life will be found? How do you define 'life'? How much does one 'lifeform' count to the likelihood? Do you count whole planets with life on it? Do highly populated planets count more? Do intelligent species count more? Do awfully reproductive species count less? Do long lived species count more or less? Does the likelihood have a time-dependence? If so, does an 'absolute' likelihood integrate over time? Etc, etc.
but the real cop-out on causality comes when scientists flat REFUSE to look for good reasons for why humans might be the explaination that you're looking for.
You don't get the point I am trying to make. I would not refuse such reasoning if it were possible to formulate it in a scientifically sensible way. With the present attempts, this is simply not the case, and discussing vague ideas, guesses and believes is not what I want theoretical physics to turn into.
In addition to this, I am convinced there is another explanation. If you don't share this opinion, I don't mind, but I myself am not willing to give up the requirements I have on scientific investigations.
Best, B.
haha... okay, I'm guilty... and I realized it after I'd posted.
ReplyDeleteI'll spend time on the next post and try to be more clear.
I'll be back!... ;)
Wait a minute. Having reviewed everything that was said I see that I did explain how and why the ecobalanced nature of the anthropic coincidences' is optimized for life.
ReplyDeleteThe coincidences are all balanced between diametrically-opposing, cumulatively-runaway, tendencies, like the near-perfect "flatness" of the universe has us hanging in the balance between runaway expansion and gravitational recollapse.
In this limited case, the AP is sometimes referred to as the "structure principle" in an effort to avoid the anthropic distinction, since it could be said that black holes are equally preferred by this physics, but how are black holes preferred by the balance between cumulatively runaway glaciation, (that is predicted by empirically derived milankovitch models), and the runaway greenhouse effect?
If the universe is optimized for black holes, rather than carbon based life, then why don't they fit with the whole of the criterion like carbon based life does?
Note: In this case anthropic selection occurs via the balance that exists between political extremists, who would have us die from either, runaway greed, or on the other side of the coin, stagnation.
Patterns in nature are the highest form of blasphemy to in modern physics, since uncertainty killed purpose in nature.
Einstein should have killed Bohr and Heisenburg, instead.
In addition to this, I am convinced there is another explanation. If you don't share this opinion, I don't mind, but I myself am not willing to give up the requirements I have on scientific investigations.
ReplyDeleteAccording to the physics that I've given to you in the past and that I've linked here today, as well as the conversation that I had with this astronomer/cosmologist/instructor,
http://sanchezluis.blogspot.com/2006/06/weird-ideas.html#comments
... you have no right to make the leap of faith that you must make in order to assume that Einstein wasn't right all along, until you do the math that is outlined in the above comments section of my conversation with Luis, that proves that he was.
Until that happens... it's still 1917.
I tend to hate this discussion.. The parameters are what they are (in fact you are guarenteed that they are something), and belly aching over fundamental causes is only interesting when the selection method is dynamic. Everything else is tautological.
ReplyDeleteFor some extreme examples of taking principles of mediocrity (also sometimes with slight abuse of terminology called the Copernican principle) google for papers by Princeton Astrophyscist Richard Gott.
He evidently uses this principle to justify space travel, as well as predicting the likely ending of popular Broadway theatre plays like Cats. With some success I might add.
-Haelfix
Some thinkers try to evade the question of why "the" existing universe has just the right constants to support life through the multiple universes argument, sometimes the idea that *all* logically possible universes exist. Then we are just the lucky ones developing in one of the tiny fraction of hospitable physical-type universes. (I have to make that last caveat because if all platonic realms exist, that includes cartoon worlds and all sorts of *descriptions* not having what we normally consider coherent laws or "physics.") Remember too that the argument that the laws had to be what they were or we wouldn't be here to comment is a false, tautological argument: of course outcomes must be consistent with starting conditions. But, that doesn't explain why the universe didn't turn out to be a barren one - with no one around to say so - instead of a hospitable one with someone to notice!
ReplyDeleteHowever, for just this universe or even a limited category to just “be” is for me a sort of existential loose end, a violation of the "principle of sufficient reason" for realness. Why this?, as Mortimer Adler, Paul Davies, Frank Tipler et al have asked. The idea that every possible universe (logically possible, or "mathematical structure" as Max Tegmark says) exists has been argued e.g. by Frank Tipler and Tegmark. Both have challenged the very idea of “existing” as a special status, asking just what that really is (it *is* hard to logically define what the difference between a platonic world and a “real” one of “stuff” is, which reminds me of the problem of defining consciousness etc.)
There are problems with that sort of perspective. For one thing, where does the parade of worlds end? Why stop with worlds that are at all like our sort of realm that seem made of “stuff” with “laws” (consistent behaviors) applying to it? Why not worlds like magical realms, with angels and demons, why not the Bugs Bunny and Road Runner cartoons, etc? Why not “God” in some sense, making for a reification at long last of Anselm’s ontological argument? Isn't that a cute irony, that those who push existential equivalency end up supporting angels, elves, fairies, and maybe big G him/herself. Furthermore: what's to stop these worlds and whatevers from interacting and interfereing with each other? Who's minding the whole mess?
Worst of all for the Bayesian probability of what we can expect to happen: the set of logically possible universes would not just be those expressing laws, but all possible ways for things to happen – just like all possible pixel arrangements for images. That means worlds where things happen just like they do here but then become chaotic etc. The number of possible arrangements that are not orderly is far more than the number that are. Hence, we have no expectation of lawful behavior in the future unless there is a genuine, underlying “virtus” to give order to a universe. I think this must come from “God” since there are not many “possible worlds” where things continue to behave lawfully anymore than there are very many “possible pictures” among pixel arrangements that are orderly scenes.(And no, the idea of self-selection does not help here. It isn’t just a matter of being in a universe with the right laws, it’s about there even being a likely continuity of laws to begin with. Even if we were in the 10^-1000 or so set of possible universes having gotten this far, we would have a tiny Bayesian chance of being in one that would continue to be like that. (Just like even if you only could be admitted to card games that already had drawn a royal flush, you now have no expectation to continue seeing lucky hands.) Tegmark and the other spaces cadets just don’t appreciate or publicize this point.
To me, the anthropic principle is an expression of a Will of some sort. Otherwise, why would things be this way? For the one universe to just happen to have the exactly correct parameters, or to have the mess created by the idea of existential equivalency - neither is philosophically elegant.
Dear island,
ReplyDeleteAccording to the physics that I've given to you in the past
I have read the links you put here, and tried to understand your claims, but it seems to me we have a very different perception of what physics is. Your comments don't explain anything of what I asked, in fact, they don't remotely have anything to do with it.
Should your convictions ever result in an equation that allows us to compute some parameters in the standard model, I invite you to sent it to me. Otherwise, feel free to insist on your interpretation of why the universe it why it is, but I'd call it utterly useless.
Best,
B.
Hi anonymous,
ReplyDeletebelly aching over fundamental causes is only interesting when the selection method is dynamic.
Depends on what you mean with dynamic. I tend to agree with you that the selection is most likely dynamic, but I can very well imagine another quantity to vary over which is not time (not even necessarily a scalar). It then causes you more belly aches with the interpretation though. I.e. do all the non-SM non-optimal configuations actually exist if the universe did not dynamically go through a process of selection?
Dont know.
Best, B.
I guess I left before seeing this:
ReplyDeleteShould your convictions ever result in an equation that allows us to compute some parameters in the standard model, I invite you to sent it to me.
Bee, you missed the fact that the background changes every time that you make a particle pair in the referenced stuff that you said that you "tried" to understand. That physics is about as simple as theoretical physics gets, so I honestly don't get how anybody that has ever studied relativity can only "try" to understand it.
What you're missing is that the number of particles in the described finite universe, MUST be disproportionally relative to the size of the universe, just like Dirac thought, so yeah... I'd say that there's an equation or two that I could send you, but how many assumptions are you willing to question?... is the real question.
Otherwise, feel free to insist on your interpretation of why the universe it why it is, but I'd call it utterly useless.
I really don't get this... "MY" interpretation is not in question. What is in question is the FACT that Einstein was never proven wrong, and he NEVER would have abandoned his finite deterministic model, had he simply known about the particle potential of the quantum vaccum in context with the effect that matter generation has on the referenced "quasi-static" model, since this CAUSES vaccum expansion, while holding the universe stable and flat.
"The AP is not a theory, and I honestly have no idea what the scientific status of 'principle' is supposed to be."
ReplyDeleteI think most proponents of the Anthropic Principle would say that the setting of, say, the cosmological constant would appear to be fine-tuned or else life could not exist. Yes, as you say, you can't use this principle to predict anything, and it is not scientifically useful. However, it would appear to indicate that our existence is fortuitous, at the very least. This lead to thoughts that we live in a "designer universe". This is anathema to physicists - hence the multiverse interpretation.
I think your comments in B and C are an attempt to bring the Anthropic Principle under scientific control, to make some sort of mathematical analysis (your natural instinct). I'm afraid this is rather doomed as the Anthropic Principle - as you say - does not belong to the traditional scientific method.
I still think the Anthropic Principle is interesting and useful (but not in the strictly scientific way you are seeking) because it deals with perhaps the most fundamental question of all: why is there existence at all, and why does it take this particular form? However, I think any discussion about it has to take place in rather an "outside of science" manner.
For example, people who dismiss the Anthropic Principle as a "selection effect" (some of the comments of this blog) do not appreciate that that does not solve the problem of selection: in that case the difficult questions just get pushed back to a deeper layer. Only the comment of "Neil" above refers to this thornier question. It is considered in depth on my blog: http://www.ipod.org.uk/reality/reality_anthropic_principle.asp
Oops ... here's the HTML link to my blog: The Anthropic Principle.
ReplyDeleteBlogs and other Internet fora strike me as having lost sight of the fact that "Anthropic Principle" was coined by the astrophysicist Brandon Carter in 1974. For some years after that, the phrase was only employed by cosmologists, for that matter, by people whose PhD adviser was Dennis Sciama. The high point of this research program is the 1986 monograph by John Barrow and Frank Tipler, which tries to situate the AP in the long human conversation about the status of teleology in philosophical and scientific reasoning. The academic authority on the AP is the philosopher Nick Bostrom at Oxford, who has nicely married the AP with some elementary Bayesian probability. We don't know the relevant probability distributions, but we gradually learn more about them over the centuries and update our beliefs accordingly.
ReplyDeleteThe term AP has since been hijacked by the string community and possibly others, and in the process, its origin in cosmology have been lost sight of. For the record, I have little time for string theory because I am a reactionary Popperian, and so have no use for the use Susskind makes of the AP.
I submit that the AP comes in two flavors: Weak and Strong. Strong lumps together a number of AP variants proposed by Barrow & Tipler whose details I don't want to linger over, because they are all quite speculative. Weak is a methodological principle, part scientific method and part common sense. I happen to think that it has predictive power, but readers are free to differ. Strong is everything but Weak, and could well be an untestable teleological statement. At the same time, I agree that the perplexities commonly pigeonholed under "fine tuned universe" are legitimate ones.
I happen to believe that the AP should be married to (and tempered by) the Rare Earth Hypothesis of Ward and Brownlie: microbes are probably common in the universe, but macroscopic life, especially intelligent life, are probably rare. Operational implication of "rare": we humans are probably unique in the Milky Way. In which case Feynman's 1959 question becomes a very fair comment: if the universe exists to permit homo sapiens to come into being, why does the performance of this drama require such a collosal stage?
Well, a bit delayed but:
ReplyDeleteI don't have Feynman's direct quote, but most of us who believe in a "designer universe"/s don't think this is just for the benefit of homo sapiens. The term "anthropic" is loose and perhaps inartful - it is supposed to imply "of a nature congenial to, and likely to, elicit formation of sentient, intelligent entities." That means ETI, not just us. As for why such a big stage, well that is IMHO part of the triangulation and mutual "interferences" of various requirements and parameters. (Even Thomas Aquinas realized, "even God" couldn't change the rules of logic because that is a structure of entailments ... He said God couldn't make the angles of a triangle add to other than 180 degrees, so I guess he didn't get non-Euclidean geometry.)
BTW, to summarize my argument: without some sort of "management" out there, the superset, ultimate ensemble etc. (per modal realist view) is so big and messy, that we can't expect ourselves per Bayesian arguments to be in a consistently orderly world. We should instead expect (per relative numbers or various types of "descriptions") to find ours to be just orderly enough, and only up to that moment, to allow our existence.
I love "Anonymous"'s quote 2 posts above this one. Although his/her 4th paragraph is a bit out there, the first 3 (especially the 2nd) are beautiful.
ReplyDelete"As anthropic principle skeptics, physicists only adopt the anthropic principle when they have no other options, and they abandon it when something better comes along. It remains to be seen if string theorists will find another way to maneuver through the string theory landscape."
... Andrew Zimmerman Jones, String Theory for Dummies (2009), page 19, bottom
And that's from a person who LIKES String Theory!
D, Bee, is a bit of a sales job for Lee Smolin's Fecund Universes theory*. I love Lee, I like what he's trying to do to "fix" the trouble with Physics Academia, beginning with Perimeter, and tomorrow ... the World!
*- I don't mind you selling FU though. It makes more sense to me than any other version I've heard of. It's unprovable of course, and for the moment, I choose to stay away from stuff like that.
In summary: I hate this subject, it fails the definition of "Science", and will never post on this thread again. Great effort though, Bee. Given the putridity of the subject, you were very concise, and coming from an Engineer, that's a compliment.