What distinguishes a theory from a framework in physics?

In summary, String Theory is a theory that has yet to make testable predictions that are different from what we already know from existing theories. Some folks believe that it's actually a collection of theories that are being fine tuned to existing knowledge and thus really isn't the ultimate theory of everything.
  • #36
I look forward to hear this:

Peter Achinstein: Scientific Speculation
Throughout the history of science controversies have emerged regarding the legitimacy of speculating in science. Three very strong views about the general practice of speculating have emerged: One, very conservative, says “never do it, or at least never publish it.” It is the official doctrine of Isaac Newton: “hypotheses have no place in experimental philosophy.” (Of course, he violated his official doctrine on several occasions). Another, more moderate position is the official doctrine of hypothetico-deductivists such as Whewell, Popper, and Hempel: speculate freely but verify before publishing. The third, the most liberal, is suggested by Feyerabend’s principle of proliferation: speculate like mad, and publish, even when you have no idea how to test your speculations.

In my talk I want to reject all three of these views. They are too simple-minded. Some speculations are good ones, some not so good. I will ask how a speculation is to be evaluated. In the process of doing so, I will consider two historically important speculations: James Clerk Maxwell’s kinetic theory speculations from 1860 to 1875, and a speculation that has been put forward by some string theorists, as well as by others, viz. that there is a “theory of everything” (whether or not it is string theory). The first, I will argue, deserves praise, the second does not.

Sabine Hossenfelder: Lost in Math
I will speak about the role of social and cognitive biases in hypotheses pre-selection, and reflect on the rationale behind the concepts of naturalness, simplicity and beauty.

Helge Kragh: Fundamental Theories and Epistemic Shifts: Can History of Science serve as a Guide?
Epistemic standards and methodologies of science inevitably reflect the successes and failures of the past. In this sense, they are in part of a historical nature. Moreover, the commonly accepted methodological criteria have to some extent changed over time. Faced with the problem of theories that cannot be tested empirically, perhaps not even in principle, it may be useful to look back in time to situations of a somewhat similar kind. Roughly speaking, previous suggestions of non-empirical testing have not fared well through the long history of science. Ambitious and fundamental theories of this kind have generally been failures, some of them grander than others. So, is there any reason to believe that they will not remain so in the future? Can we infer from history that empirical testability is a sine qua non for what we know as science? Not quite, for it is far from obvious that older scientific theories can be meaningfully compared to modern string theory or multiverse physics. History of science is at best an ambiguous guide to present and future problems, yet it does provide reasons for scepticism with regard to current suggestions of drastic epistemic shifts which essentially amounts to a new “definition” of science.
 
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  • #37
in germany we have a hard debate about this theme. It is time for such a conference.
especially particle physicists are now more and more aggressive and see that they lost the game

Here they pray sarcastically against Ed Witten

"Witten unser, der Du bist in Princeton,
Publiziert werde Dein Name,
Dein Bran komme, Deine Theorie bestehe
Wie in Dimensionen Also auch auf Erden
Unsern täglich’n Einfall gib uns heute,
Und vergüt’ uns uns’ren Kult,
So wie auch wir nur geben unsren Huldigern.
Und führe uns nicht zu Versuchen
Sondern erlöse uns von der Prüfung
Denn Dein ist der String, und die Kraft
Und die Unwiderlegbarkeit
In Ewigkeit. Amen."
 
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  • #38
marcus said:
You would dismiss this as "lamppost physics"? :

The first paper you linked to is, the second you linked to is not. The second is some work related to scanning the parameter space within loop quantum cosmology, where clearly some of the models within that set have testable predictions and some do not. The first paper on the other hand is lamppost physics by definition. In fact it is an attempted proof that there is a lamppost at all! Inflation has a tendency to wipe out most primordial imprints of quantum gravity, so the paper is making the point that at least a small portion of the parameter space can leave an imprint in the CMB.

Anyway I think you misunderstand me, there is nothing necessarily wrong with lamppost physics, there are many great models that are constructed as such (indeed some have won Nobel prizes). Most physicists write many such things within their lifetime, I certainly have. Indeed it is important to look where you can, and we do the best we can under the situation. However the point of the analogy is that there is often very good models/ideas that are NOT falsifiable right from the getgo and just because something is falsifiable, does not necessarily endow it with some special virtue in and of itself as the needle in the haystack example tries to show. For that you typically need to look at the details of the model.
 
  • #39
MacRudi said:
in germany we have a hard debate about this theme. It is time for such a conference.
...
...

"Witten unser, der Du bist in Princeton,
Publiziert werde Dein Name,
Dein Bran komme, Deine Theorie bestehe
Wie in Dimensionen Also auch auf Erden
Unsern täglich’n Einfall gib uns heute,
Und vergüt’ uns uns’ren Kult,
So wie auch wir nur geben unsren Huldigern.
Und führe uns nicht zu Versuchen
Sondern erlöse uns von der Prüfung
Denn Dein ist der String, und die Kraft
Und die Unwiderlegbarkeit
In Ewigkeit. Amen."
heh heh :oldbiggrin:
I found an English translation in google books--- from Unzicker "Bankrupting Physics"
https://books.google.com/books?id=dcgTAAAAQBAJ&pg=PA183&dq="Our+witten+who+art+in+Princeton,+published+be+thy+name.+Thy+brane+come"&hl=en&sa=X&ved=0ahUKEwif_sC9zcHJAhVI82MKHQoFCV8Q6AEIHTAA#v=onepage&q="Our witten who art in Princeton, published be thy name. Thy brane come"&f=false

A different version in English is here:
http://resonaances.blogspot.com/2007/01/cern-th-2007.html
 
  • #40
I'm excited about this conference and didn't know about it! My personal view is that too much emphasis in our field has shifted from philosophy and conceptual interpretation towards doing calculations. I agree e.g. with the amazement of Bell about why people haven't paid more attention to Bohmian mechanics and the critics it gets from 'opponents'. Also populair science books don't devote much space to philosophy.

And to be honest, I don't understand in many cases when topics here are closed with the argument that it is 'metaphysics' or 'philosophy'. That's a sidermark, but it shows the distinction people make between mathematical models and their interpretations.

For me this is one important reason to be interested in string theory. Its very existence raises a lot of interesting questions and possible answers to these issues in a concrete way.
 
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  • #41
Hi Haelfix, thanks for your reply. I was just getting off to bed,will respond in the morning.
 
  • #42
haushofer said:
I'm excited about this conference and didn't know about it! My personal view is that too much emphasis in our field has shifted from philosophy and conceptual interpretation towards doing calculations. I agree e.g. with the amazement of Bell about why people haven't paid more attention to Bohmian mechanics and the critics it gets from 'opponents'. Also populair science books don't devote much space to philosophy.

And to be honest, I don't understand in many cases when topics here are closed with the argument that it is 'metaphysics' or 'philosophy'. That's a sidermark, but it shows the distinction people make between mathematical models and their interpretations.

For me this is one important reason to be interested in string theory. Its very existence raises a lot of interesting questions and possible answers to these issues in a concrete way.

I can understand why physicists don't want speculations because all the last 70 years we had much speculations about quantumtheory and their interpretation. Heisenberg saw this long before and said that we only should calculate and don't want to see in the black box (although he was much more afraid of the positivistic lame middleintelligent physicists who only take all for granted what he was talking about without thinking by themself) . But you cannot forbid to look in the black box and then a lot of esoteric religions, believing systems developed over the time. Evene the religions itselves are now argueing with quantumtheory for their believing system (free will, probability etc.)
And now we have a lot of physicists who are religious in some kind also and want to defend this established physics for their believing system too. Big bang with creator, Quantumtheory for free will etc.
We have now similar situation as it was in old greek before Platon.

On the other hand we have now the first possibility with string theory to get a theory which cannot be misused for religious believing system because it is explicitely without a creator, without indeterministic interpretations. This makes a lot people afraid.

Freud explained this behaviour and thinking behind of such physicists and religious people psychologically that it is a narzistic violation. We had it all the time in science history.
It was with the end of ptolomaic worldview. With darwins evolutiontheory and now we get it with modern physics of multiverses especially which makes most afraid.
 
  • #43
MacRudi said:
On the other hand we have now the first possibility with string theory to get a theory which cannot be misused for religious believing system because it is explicitely without a creator, without indeterministic interpretations.
You bet?
 
  • #44
fresh_42 said:
You bet?

I would never bet ;-) You can create a religion out of Harry Potter also lol

But Stringtheory means in many views a complete paradigm change for all established religions and especially for esoteric believing systems. And most will not follow them. Hopefully! Otherwise we can say that they are currupted lol

For christians (jews, muslim) it would be a complete change and they have no fundament anymore they can say that it is also proved by science what they believe (creator, free will ...). And this is most important I think.
 
  • #45
MacRudi said:
But Stringtheory means in many views a complete paradigm change for all established religions
How conforting it feels for me to think that science can eventually describe the "Godly" occurrences or "miracles", as a basic example, if a God could and would perform such a feat. String theory is only one possible "theory of everything" that leads humans towards Godly powers so at some point you get off the hype and look at it realistically and see that science and religion don't "have" to conflict. It is all human interpretation of stories, written by fallible humans. Fallible in science as well. To suppose all the atoms are vibrating strings which oscillate with deterministic interference undermining our ability to physically alter the universe seems like the most far-fetched science/religion theory, to date, in my humble opinion.
 
  • #46
jerromyjon said:
How conforting it feels for me to think that science can eventually describe the "Godly" occurrences or "miracles", as a basic example, if a God could and would perform such a feat. String theory is only one possible "theory of everything" that leads humans towards Godly powers so at some point you get off the hype and look at it realistically and see that science and religion don't "have" to conflict. It is all human interpretation of stories, written by fallible humans. Fallible in science as well. To suppose all the atoms are vibrating strings which oscillate with deterministic interference undermining our ability to physically alter the universe seems like the most far-fetched science/religion theory, to date, in my humble opinion.

yes maybe you are right. Some see in the mathematics/theoretical physics the way to touch godly power like Paul Halmos
"I am not a religious man, but it’s almost like being in touch with god when you’re thinking about mathematics."
 
  • #47
MacRudi said:
yes maybe you are right. Some see in the mathematics/theoretical physics the way to touch godly power like Paul Halmos
"I am not a religious man, but it’s almost like being in touch with god when you’re thinking about mathematics."
I'm more and more in doubt about "the beauty of math". Of course it exists, I can see it, too. We all have a sense of beauty and aesthetic. One of my favorites is the infinity of primes for you can tell every school kid how it is proved. Same with Cantor's diagonal argument. Or the concept of normal subgroups. All of them have a kind of inner beauty. However, when I remember, e.g. Galois' original text which you can hardly follow. (I've found it by chance in an old book beneath a bunch of old books the library wanted to get rid of because they feared the work to be done to catalog all of them.) And next how Artin wrote his textbook about Galois Theory and then how Bourbaki would have done it - then all three describe the same thing in a completely different way and language. Doesn't that mean that what's regarded as beautiful simply changes as times go by? Personally I find the AdS explanation not very convincing but couldn't this just change when we once get used to it (if proven suitable.)?
 
  • #48
fresh_42 said:
I'm more and more in doubt about "the beauty of math". Of course it exists, I can see it, too. We all have a sense of beauty and aesthetic. One of my favorites is the infinity of primes for you can tell every school kid how it is proved. Same with Cantor's diagonal argument. Or the concept of normal subgroups. All of them have a kind of inner beauty. However, when I remember, e.g. Galois' original text which you can hardly follow. (I've found it by chance in an old book beneath a bunch of old books the library wanted to get rid of because they feared the work to be done to catalog all of them.) And next how Artin wrote his textbook about Galois Theory and then how Bourbaki would have done it - then all three describe the same thing in a completely different way and language. Doesn't that mean that what's regarded as beautiful simply changes as times go by? Personally I find the AdS explanation not very convincing but couldn't this just change when we once get used to it (if proven suitable.)?

It was always the same in mankind history that we saw the beauty in mathematics, when we find a lot of descriptions from different views on the same thing. Then we "see" something which is behind or is underlying and especially when we "see" kind of reality we can find in the real world. The most powerful beauty lies in the stringtheory that we have a lot of equivalences ( think of T duality) , which we are used to in General Relativity too (acceleration/gravity). And the best is, that out of this model there were many problems in mathematics proved/solved like topologies and their axiomatik, which makes sense now and is not anymore any assumption.

We always learn at school that we live in an euclidic world and know that two parallel lines have always the same distance and cannot cross. It was a hard principle like a dogma. Since Einstein (although we knew that the Earth is not flat ;-) ) we know it can and is a princple of spacetime in universe. It was not so convincing for the most. An old naiv believing system was completely vanished since 100 years now. Now it is for us not a problem anymore to believe that parallel lines can even cross. The same will be with AdS in time.

The old Idea of natural numbers like the pythagoreer had, that it must be an underlying reason for the numbers we have now since Plato in ideas and know since Wittgenstein that we are playing games with mathematical language. We are always since old greek in this tensionfield between Platos ideas and wittgensteins game of mathematical language to see the sun directly out of the cave.

btw FYI A new nice book if you can read german.
Thomas Bedürftig /Roman Murawski -
Philosophie der Mathematik - De Gruyter Verlag
 
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  • #49
I feel very comfortable with my Platonism, despite Zorn, Goedel, constructivism, Bohr, Einstein and Schrödinger; or Wittgenstein. The latter doing with words what Pythagoras did with numbers: esoteric nonsense. I even subsume musical compositions and all concepts of religion under Plato's ideas dropping thus the question about existence. I admit this might be a little lazy. :cool:

But back to AdS. What does a hyperbolic curvature prefer to a elliptic one? (Assuming both are locally flat, with some very large charts in spacetime.)
 
  • #50
fresh_42 said:
I feel very comfortable with my Platonism, despite Zorn, Goedel, constructivism, Bohr, Einstein and Schrödinger; or Wittgenstein. The latter doing with words what Pythagoras did with numbers: esoteric nonsense. I even subsume musical compositions and all concepts of religion under Plato's ideas dropping thus the question about existence. I admit this might be a little lazy. :cool:

But back to AdS. What does a hyperbolic curvature prefer to a elliptic one? (Assuming both are locally flat, with some very large charts in spacetime.)

you seem to have a widespread humanistic education. ;-) That's great. :-) In our days not many have this anymore. :-(

But to the musical composition and kind of religion as philosophy I must say that this was included in the the thinking of the Pythagoreer too. Platon took that over from them in his ideas. With ratio of course and not so esoteric anymore because he found them criminal to hide their knowledge about the principles of mathemtics and nature and who made an esoteric cult out of it. Plato was a rebell in his time and wanted to teach all his knowledge for all people who were intellectual able to understand it in his academia.

hyperbolic is for some reasons more attractiv. We see e.g. how it works better for gravity in an additional spacedimension and we see hyperbolic structures in black holes as hint. On the other side we can explain much better phenomens like accelerating expansions in spacetime. I think these are the main reasons so far. If we calculate for möbius transformations in compactified space then it could be also that elliptic could be a good approximation too, but I don't know really. Never looked it up. String theory is now over time a good in itself extremely consistant model and is working with hyperbolic space.
 
  • #51
Here to read an article of Richard Dawid about the T duality and S duality as equivalence principle for ontology and scientific realism
Richard Dawid is the conference CEO in Munich on monday. He is theoretical physicist and philosopher at the mathematical philosophy institute in munich

http://homepage.univie.ac.at/richard.dawid/Eigene%20Texte/10.pdf
 
  • #52
MacRudi said:
http://homepage.univie.ac.at/richard.dawid/Eigene%20Texte/10.pdf
From the end of section 3

"Scientific theories in general cannot be expected to fit all possible empirical evidence. The
specific status of string theory changes this situation in two respects. First, string theory offers
a number of reasons for being called a final theory. (see e.g. (Witten 1996), (Dawid 2004).)
Therefore, the assertion that string theory, if fully understood, could fit all possible empirical
evidence, has a certain degree of plausibility. Second, in the context of string theory the claim
of Quinean underdetermination is not based on the accidental occurrence of several
empirically equivalent theoretical schemes but on a physical principle, the principle of
duality, which represents a deep characteristic of the involved theories and may be expected
to be a stable feature of future fundamental physics. It seems plausible to assume that the
duality principle will continue to play an important role even if string theory changed
substantially in the course of future research."

Parts of "string theory" are stepping stones regardless...
 
  • #53
yes but nevertheless it is like a war, what happens right now.

Here a capital out of a book from the same author but only in german, which describes both positions and what is underlying in this war against String physicists
very good analysis. From the book: Wenn Naturwissenschaftler über Naturwissenschaftlichkeit streiten, in Pseudowissenschaft. Konzeptionen von Nicht-/Wissenschaftlichkeit in der Wissenschaftsgeschichte , D. Rupnow, V. Lipphardt, J. Thiel und C. Wessely (eds.): 395-416, Suhrkamp 2008.

http://homepage.univie.ac.at/richard.dawid/Eigene%20Texte/14.pdf
 
  • #54
The only German word I know is Zitterbewegung, laugh out loud...
 
  • #55
jerromyjon said:
The only German word I know is Zitterbewegung, laugh out loud...
I've recently read "Ansatz" in an English scientific article!
 
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  • #56
jerromyjon said:
The only German word I know is Zitterbewegung, laugh out loud...

oh you will know a lot more, when you studied physics or mathematics. Most words in mathematics and physics are german words. Eigenvector, Ansatz, Gedankenexperiment and much more. All german words.

;-)

but to come back to the theme: The war. Actually there was an experiment which should prove holographic principle in spacetime. This is a speculation of Stringphysicist Lenni Susskind that there is such a principle. But Hogan is against stringtheory and wanted to show how absurd all these theories are. Hogan is not everyone. but read by yourself what it was about.

http://backreaction.blogspot.de/2015/12/what-fermilabs-holometer-experiment.html
 
  • #57
or ansatzes is an educated guess that is verified later by its results.

This should sum it up: String theory nor any other might ever be able to predict random quantum interference (zitterbewegung?) when the ansatz of an atom causing physical action is only half the non-local (eigen?) value?
 
  • #58
jerromyjon said:
or ansatzes is an educated guess that is verified later by its results.

This should sum it up: String theory nor any other might ever be able to predict random quantum interference (zitterbewegung?) when the ansatz of an atom causing physical action is only half the non-local (eigen?) value?

random quantum interference should be Zitterbewegung? Never heard before.
 
  • #59
Even no result is a result! For how long do they search gravitational waves now? For how long have black holes been regarded as a mathematical peculiarity? But remember this if those "too far" galaxies won't be found.

Seemingly this kind of war you are talking about belongs to physics. I just hoped it had been kept in the 20th century when fundamental concepts of as well physics as mathematics have been challenged. Things have changed a lot since Hilbert and Bohr. Judging content by publications, reputation or fields of research obviously not. I'd wish scientific staff would live a lot more without prejudices and Vanity Fairs.
Not everyone with an unusual idea or a new point of view is automatically a trisectionist. (Those people writing letters to faculties "proving" they can divide angels into three parts or in former times claimed to have solved FLT.)
 
  • #60
fresh_42 said:
Even no result is a result! For how long do they search gravitational waves now? For how long have black holes been regarded as a mathematical peculiarity? But remember this if those "too far" galaxies won't be found.

Seemingly this kind of war you are talking about belongs to physics. I just hoped it had been kept in the 20th century when fundamental concepts of as well physics as mathematics have been challenged. Things have changed a lot since Hilbert and Bohr. Judging content by publications, reputation or fields of research obviously not. I'd wish scientific staff would live a lot more without prejudices and Vanity Fairs.
Not everyone with an unusual idea or a new point of view is automatically a trisectionist. (Those people writing letters to faculties "proving" they can divide angels into three parts or in former times claimed to have solved FLT.)

We had this war often in the 20th century. first when Einstein came out with his GR. Later with Kopenhagen definition/interpretation of QT. In the scientific community is often a war. Mostly it is about groupthinking, reputation and financial support. The first time and phase in history where we had some kind of peace was between the 1970s to about 1995 (Dawid says 2002 but gave the latence time after Witten showed M Theory and where some people get aware, what it meant for them) This was the time where we had really a free open research and no scientific wars.
 
  • #61
MacRudi said:
I can understand why physicists don't want speculations because all the last 70 years we had much speculations about quantumtheory and their interpretation. Heisenberg saw this long before and said that we only should calculate and don't want to see in the black box (although he was much more afraid of the positivistic lame middleintelligent physicists who only take all for granted what he was talking about without thinking by themself) . But you cannot forbid to look in the black box and then a lot of esoteric religions, believing systems developed over the time. Evene the religions itselves are now argueing with quantumtheory for their believing system (free will, probability etc.)
And now we have a lot of physicists who are religious in some kind also and want to defend this established physics for their believing system too. Big bang with creator, Quantumtheory for free will etc.
We have now similar situation as it was in old greek before Platon.

On the other hand we have now the first possibility with string theory to get a theory which cannot be misused for religious believing system because it is explicitely without a creator, without indeterministic interpretations. This makes a lot people afraid.

Freud explained this behaviour and thinking behind of such physicists and religious people psychologically that it is a narzistic violation. We had it all the time in science history.
It was with the end of ptolomaic worldview. With darwins evolutiontheory and now we get it with modern physics of multiverses especially which makes most afraid.

Well, for me the issue is not religion. It is about interpretation. We should not only calculate, but also interpret. Sometimes I have the feeling that there is an attitute that concepts and interpretations are left over for philosophy. And when philosophers do talk about these issues, it is not seldomly being regarded as irrelevant by physicists. I can e.g. understand that with the history of QM people people have become reluctant and suspicious to talk about interpretations of QM, but as far as I can see it's a valid debate. Somehow it seems a bit odd to me that we have developed string theory and still have interpretation-issues with QM. I rarely see the question being adressed whether the interpretation-issue of QM can affect the quantum gravity debate.

For me the reason why the interpretation-issue of QM doesn't get more attention is more a matter of sociology than rationality.
 
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  • #63
Speaking of the Munich conference "Why trust a theory?" a philosopher of science named Massimo Pigliucci (MP)provided an extensive account of the first day's talks.
Here are excerpts of his summary of the first two talks of the day---by David Gross and Carlo Rovelli:
==quote from MP==
...
...
So, let us get started with David Gross, talking on “What is a theory?” Gross began by noticing that philosophy and physics have, ahem, “grown apart” over the years — citing the now classic quote by Richard Feynman about philosophy, birds, and ornithology. Gross himself said, however, that he envies the pioneers of quantum mechanics and relativity, who were well versed in philosophy, and he still thinks there is much the two fields can say to each other.
...
...
The crucial issue is strategy, not ideology: we shouldn’t be discussing what science is or is not — since the scientific method itself evolves continuously — but rather what works and what doesn’t. One of the reasons for this meeting is that physics makes predictions that are far out of the current limits of experimentation, around the energy level at which all forces, including gravity, unify (10^28 eV, the Planck scale).
...
...
Theorists may give up, or they may play with extrapolation, or toy models (i.e., thought experiments). They could also adopt strategies from other fields, like mathematics, where beauty is a criterion for success. [Uhm, that’s pretty dangerous territory…]

String “theory” (framework, really) started about 47 years ago out of a data fitting problem, and it didn’t even feature strings at the time, as it initially was a theory of the behavior of gauge mesons. Then people immediately realized that string theory “must” contain gravity, and it is this sort of unexpected theoretical consequences that have kept the excitement going.

But string theory isn’t really a theory — you can’t write its equations on a t-shirt, after all! String theory and quantum field theory are, according to Gross, part of a larger framework. The problem is that we don’t have any idea of how the framework in question picks the Standard Model, hence connecting to experimentally based physics. Here, Gross also thinks, is perhaps where philosophers — who are used to think carefully — may help.
...
...
Gross thinks that the “no alternatives argument” introduced by Dawid (see below) is a powerful one in favor of string theory, as it is not easy to change a framework. [I guess Kuhn would call these paradigms?] There is also an “unexpected explanatory power” argument based on the fact that the string framework connects elegantly with a number of other known notions in physics. Finally, there is the “meta-inductive argument,” according to which past speculative but strongly supported (by the physics community) theories have turned out to be correct. As I said, these are the argument actually advanced by the conference organizer, Richard Dawid, so I’ll return to them shortly below.

[Some of the testiness underlying the conference became briefly evident during an exchange between the next speaker, Rovelli, and Gross. Rovelli pointed out that Gross had gone way over time, and asked whether the organizers would take time out of his talk or from dinner. To which Gross replied that he will surely interrupt Rovelli’s talk too. And he did, somewhat rudely I must say, follow up on his threat. Ouch.]

Next was Carlo Rovelli, on “Non-empirical confirmation: just a cover-up for the failures of string theory?” He started out by saying that Dawid makes good points in his paper on non-empirical confirmation, about the analyzability of the context of discovery, for instance. But also that Dawid confuses the context of discovery with the context of validation. [Smells of Popper here.] He also confuses descriptive and normative philosophy of science, misreading the history of string theory, since the latter has failed by the lights of its own stated criteria for validation.

Rovelli traced the distinction between context of discovery and of validation to Reichenbach (1938). The time between the two can be very long, as for instance between the publication of Copernicus and Galileo’s books on the structure of the solar system (1543 vs 1610).

[Rovelli has a good general point, though I must also signal that modern philosophers of science do not make a sharp distinction between the two contexts, as discovery and validation are continuously interacting processes.]

Theoretical work is guided by preliminary appraisal, i.e. weak evaluation. This aids the decision of whether to take the theory seriously enough to develop it and test it further. Dawid’s criteria are good as preliminary, weak evaluations of string theory. But they fail as validations.

Rovelli, amusingly, quotes Lakatos [an influential student of Popper]: “It is no success of Newtonian theory that stones, when dropped, fall towards the Earth.” The speaker then listed a good number of past theories that seemed very promising, and yet turned out to be very clearly wrong.

String theory itself set out validation criteria early on in its history: computing the parameters of the Standard Model from first principles, for instance, or deriving the existence of three families (of particles) from first principles, or predicting the sign of the cosmological constant, or predicting new particles to be discovered at LHC energy levels, or low energy supersymmetry, and so forth. According to Rovelli, all of these failed, turning string theorists into the mythical fox who argued she didn’t really like the grapes, once it was clear that she couldn’t reach them… [Nice classical reference to Aesop!]

There are alternatives, like loop quantum gravity (which actually can be written on a t-shirt!). For Rovelli this is just as not yet validated as string theory, but at the least its existence rejects the oft-made claim that string theory is the only game in town. He also cautioned about confusing “tenure in major universities with consensus of the scientific community,” pointing out that Gross won the Nobel and has a position at a major university because of his non-string work.

Rovelli concluded by pointing out that claiming that a theory is valid even though no experiment has confirmed it destroys the confidence that society has in science, and it also misleads young scientists into embracing sterile research programs. [Lakatos would have called them “degenerate.”]

After coffee break it was Dawid’s turn with “Non-empirical Confirmation.” Though his focus is on string theory, his ideas are applicable to other frameworks as well. He began by acknowledging that the theory hasn’t found empirical confirmation for quite some time, and moreover that this state of affairs may continue long into the future. Nevertheless, ...
===quote===
https://platofootnote.wordpress.com/2015/12/08/why-trust-a-theory-part-i/
http://www.whytrustatheory2015.philosophie.uni-muenchen.de/index.html
http://www.whytrustatheory2015.philosophie.uni-muenchen.de/program/index.html
http://www.whytrustatheory2015.philosophie.uni-muenchen.de/media/index.html
 
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  • #64
It is nice to see that leading physicists are no longer ashamed of discussing philosophy of physics. :smile:
 
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  • #65
I apologize for my quite intermittent prescence on the forums, life is just keeping me too busy. Good to see some of the old users still here!

marcus said:
The crucial issue is strategy, not ideology: we shouldn’t be discussing what science is or is not — since the scientific method itself evolves continuously — but rather what works and what doesn’t.

marcus said:
The problem is that we don’t have any idea of how the framework in question picks the Standard Model, hence connecting to experimentally based physics.

I think these two lines sums is up well. To me it also means that wether a scientist thinks that string theory (here I mean the framework, and "way of thinking") is the most rational way to make things work or not, to a certain extent mirrors their preferred logic of reasoning about fundamental physics.

So - if we have no idea how ST framework "picks" the SM, the quesion is if it can still be a viable strategy? I think not even those that are not fans of ST, will deny that the ST framework has decent flexibility as framework for adapting theories. But the question is, if the core problem is variability or selectivity? IMO an evolutionary model, and evolving framworks such as evolution of life, or learning, needs both. Of course some of the "selections" takes place against interactions with the environment of the host systems (scienticsts making experiments in this case) but a viable strategy should imo still _at each stage of evolution_ be well balanced between options and guidance, otherwise the host system risks destabilize and be deselected.

The idea that a microstructure such as a multidimensional strong encodes interactsion is perfectly rational and sound IMO. This is not at all the problem. The problem is that it is not as sound, to postulate the details in such a complex model from nothing. There is something missing in the strategy here. To make this complete me need a still missing guiding principle, for how to connect these non-observable microstructures. I think these principles exists, but they aren't found yet. And as far as I see it, most string papers I have seen are using a way of reasoning that makes me thing it will NOT be found from that side.

/Fredrik
 
  • #66
Hi Fredrik, your post #65 makes it look as if I said those two things. You write that "marcus said" but of course I did not say those things. Just to be clear: they are not my words, they are quotes from Massimo Pigliucci one of the speakers at the conference, who took notes on what the other speakers said.
 
  • #67
Ah you're right Marcus, sorry for beeing carless about quotations! I used the quote button but forgot to edit it to make it clearer that you quoted someone else.

/Fredrik
 
  • #68
Demystifier said:
String theory is certainly not more "untestable" or more "religion" than, e.g., loop quantum gravity (LQG).
big bang quote " I guess I prefer my space stringy instead of loopy " :smile:
 
  • #69
marcus said:
So, let us get started with David Gross, talking on “What is a theory?” Gross began by noticing that philosophy and physics have, ahem, “grown apart” over the years — citing the now classic quote by Richard Feynman about philosophy, birds, and ornithology. Gross himself said, however, that he envies the pioneers of quantum mechanics and relativity, who were well versed in philosophy, and he still thinks there is much the two fields can say to each other.
...
...

In your following part you have left out, what Gross was really saying on the congress. Here the more important footnote:

"Gross proposed to distinguish among frameworks, theories, and models. Classical mechanics, quantum mechanics and string “theory” are not theories, but rather frameworks. Theories are something like Newton’s or Einstein’s theory of gravity, or the unfortunately named Standard “Model.” Theories can be tested, frameworks not so much. Models include the BCS model of superconductivity, or BSM (Beyond Standard Model) models.

According to Gross, quantum mechanics, for instance, cannot really be tested directly. But the Standard “Model” can. Also, theories (at the least in physics), are compact enough that they can apparently be written on a t-shirt. Not so for frameworks."

I think this is the best description, what Gross had to say and was as introduction to the congress a very important hint for further discussions.
 
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