Is string theory a theory?

  • #1
potato123
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I heard that in order for something to become a theory it must be tested.
 

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  • #2
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Yes, String Theory is a theory. Its chief problem is that it 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.

There are other theories competing in the same space that don't have as much traction. Also many other physicist feel that String theory has sucked a lot of the oxygen out of the limited research budgets in academia.
 
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  • #3
mathman
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The definition of "theory" is not as precise as for example "electron". As a result some may object to using the term for string theory.
 
  • #4
Demystifier
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I heard that in order for something to become a theory it must be tested.
A theory does not need to be tested in order to be theory.

But there is another reason to think that string theory, in a certain sense, is not really a theory. A well-defined theory needs to have a well-defined set of general principles and assumptions, from which everything else should be derivable, at least in principle. String theory lacks this property, so people sometimes say that string theory is not really a theory, but only a theoretical framework.
 
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  • #5
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A well-defined theory needs to have a well-defined set of general principles and assumptions, from which everything else should be derivable, at least in principle. String theory lacks this property, so people sometimes say that string theory is not really a theory, but only a theoretical framework.

Hm ... was quantum theory derived from a well-defined set of general principles and assumptions in the first place? When I look at the history it rather seems that it was extended ad-hoc in some step-by-step manner.
 
  • #7
serp777
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Seems more like the string religion. No predictions, not that much evidence, and no apparent way to observe something 50 orders of magnitude that small. I mean considering it seems almost impossible to observe something on the 10^-32 meter magnitude, it seems even more impossible to observe something as small as a string. There's no good reason to believe that string theory is true at all. Its ambiguity and unfalsifiability make it equivalent to Yahweh or whatever. It also seems like there are way to many different versions of string theory, which makes it seem like the different sects of Christianity. I guess it does have one prediction though--a multiverse.
 
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  • #8
nrqed
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Seems more like the string religion. No predictions, not that much evidence, and no apparent way to observe something 50 orders of magnitude that small. I mean considering it seems almost impossible to observe something on the 10^-32 meter magnitude, it seems even more impossible to observe something as small as a string. .
That is not relevant. To see this, one can ask: according to standard QED, would there ever be a way to "directly" observe an electron? The answer is clearly no, and yet QED is extremely successful as a quantum theory. The point is that whether a particle is "small" or not (this needs of course to be defined, given that we are discussing quantum physics) is not directly related to whether the theory can be tested or not.
 
  • #9
serp777
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That is not relevant. To see this, one can ask: according to standard QED, would there ever be a way to "directly" observe an electron? The answer is clearly no, and yet QED is extremely successful as a quantum theory. The point is that whether a particle is "small" or not (this needs of course to be defined, given that we are discussing quantum physics) is not directly related to whether the theory can be tested or not.

That depends on your definition of directly observe. I don't assume directly observe means only with your eyes. Directly observe in my case means that you can use some instrument or device or method to measure and determine its existence; my point was also that due to the uncertainty principle, it suggests that its impossible that we could never measure anything slightly accurately even close to the Planck length. You can clearly see the effects of electrons like the trails they leave which is an observation in my submission. its basically impossible to ever build a device that could observe smaller than the Planck length since you're limited by the particles you have and that's kind of the entire point of the uncertainty principle. Then to make matters worse a string is something like 50 orders of magnitude smaller. It also wasn't just about the size, it was also about the lack of predictions and the number of different string theory sects. QED has predictions and concrete results and supporting observations. Until string theory has any of those things it resembles a religion more than anything. Its the combination of unobservable, unfalsifiable, and its lack of predictions. That's exactly what God is except that people actually do predict stuff like judgment day.
 
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  • #10
haushofer
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Is mathematics also a religion? Your labeling depends heavily on the fact that you classify string theory as a theory in physics. I think the border between physics and math is vading.
 
  • #11
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Suppose that physicists knew the general principles of QFT and some toy models such as ##\phi^4## theory, but do not knew Standard Model, do not knew QCD, and do not knew QED. Would QFT be a testable theory? It wouldn't! It would not really be a physical theory, but only a physical theoretical framework.

String theory, in the current state of understanding, is something like that.
 
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  • #12
serp777
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Is mathematics also a religion? Your labeling depends heavily on the fact that you classify string theory as a theory in physics. I think the border between physics and math is vading.
That's a fallacy, also known as the false analogy. Math has concrete results in a variety of fields and it is used in physics to make predictions. The usefulness, productivity, and efficacy of math makes it completely different from string religion. Furthermore, are you seriously putting string religion and mathematics on the same level? A language is simply a way of communicating information and coming to conclusions based. String theory is a description of reality whereas mathematics is used to make theories which are descriptions of everything. It would be like asking if English was a religion because it was used to construct the bible. No sorry, that makes no sense.

And no, my labeling does not depend whatsoever on the label of string theory as a theory. I never made that kind of semantics argument and I don't call the theory evolution or Relativity or QM a religion for instance. I call string theory a religion because its unfalsifiable, untestable, makes no predictions, it has several different mutually exclusive sects, and it has no concrete results. Its identical to God except that with God you could actually predict judgment day or the return of Jesus or whatever.
 
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  • #13
haushofer
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That's a fallacy, also known as the false analogy. Math has concrete results in a variety of fields and it is used in physics to make predictions. The usefulness, productivity, and efficacy of math makes it completely different from string religion.

String theory can and has been used to solve mathematical problems from a very different perspective; that's how Witten earned his Fields Medal. Also, string theory has given us concrete examples of holography, which makes us apply string theory, supersymmetrisch and supergravity theories to condensed matter.

As Demystifier says, string theory is a framework, like quantum field theory. In that sense it is not 'a' theory, like the standard model. Your labeling of string theory as a 'religion' doesn't make sense, because string theory is a very conservative extension of high energy physics. Whether this extension is still worthwile persuing depends on what you want to investigate with string theory, but my answer would be 'yes'.

Besides, if you know your physics-history, you know that your classifications "usefulness, productivity, and efficacy" are sometimes very hard to estimate. How usefull were Maxwell's theory of electromagnetism or pure number theory when it was developed?
 
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  • #14
SteamKing
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I heard that in order for something to become a theory it must be tested.
Not necessarily. To be a valid theory, it must be tested and the results of the test shown to agree with the theory.

There are many theories which have been proposed over the years, but only some have been tested and shown to be valid.

For example, there was the phlogiston theory which proposed that an element called phlogiston was released when something burned.

Phlogiston theory was taught for a number of years until it was shown to be invalid.

https://en.wikipedia.org/wiki/Phlogiston_theory
 
  • #15
Haelfix
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This topic comes up frequently on this board for some reason.

First of all, this is a board about beyond the standard model physics, which means that we are discussing theories that have not been tested, and indeed might *never* be tested. Almost all of high energy physics is about a set of models and theories that live at energy ranges that are currently out of reach of probes. Sometimes these models have indirect echoes in observable energy ranges which someone might be able to test (although frequently verification of those echoes does not logically imply the veracity of the theory). Sometimes there is absolutely no indirect consequence that is testable, and indeed it only provides postdictions of certain quantities. Sometimes a subset of a given theories parameter space outputs a model with testable consequences, but other parts of that space are not verifiable thus nonverification of the former simply entails exclusion limits. And much more frequently, sometimes people haven't worked through the details of a theory well enough to make any statement whatsoever!

Nevertheless, theorists frequently believe that a model or theory is true, even in the complete absence of experimental confirmation. This is a very long tradition in HEP physics. For instance the existence of the top quark was postulated long before it was found. An example of a current btsm theory that is currently not testable (but may or may not have observable consequences that we could test soon), but nevertheless widely believed is the statement that the neutrinos that we see are actually Majorana fermions.

Now, String theory is an example of a framework where the exact details of the theory have not been worked out. Sometimes people create toy models (simplifications) of the full theory that gives a specific model that has indirect testable consequences at accessible energy ranges, but these models are typically oversimplified, reached via difficult approximations and/or its not obvious why one should believe them as opposed to any other model within the stringy framework. Nevertheless, the full theory is still useful to a lot of researchers and believed to be part of the description of nature, and in particular quantum gravity. The reasons why this is a widely held belief are essentially the same reason why people believed in the existence of the top quark before it was found. Namely we are led there by a sequence of observations, logic and mathematical deductions and consistency checks. Explaining what all of those are in detail of course is the subject of a textbook, not a forum post.

Anyway, all this to say is that there is nothing special about string theory. It is merely one in a long line of BTSM theory proposals that are currently a work in progress, and very much how this business has always been conducted by researchers. Whether you want to call it 'science' or not, is a matter of personal philosphy and semantics.
 
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  • #16
haushofer
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In my experience, both in real life and on forums, the only people who are passionately agains string theory, calling it a religion and so on, are laymen who have never published a single paper. I guess it is something sociological.
 
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  • #17
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String theory is certainly not more "untestable" or more "religion" than, e.g., loop quantum gravity (LQG). Yet, nobody accuses LQG for having those features. Why is that? I think only string theory is accused because it is a sociological reaction to the fact that string theory is much more popular and much more known than LQG and other "untestable" theories. A moderate critic may say: OK, physics needs to investigate speculative theories, but one should not invest so much money and effort to only one such theory. When something is much more popular than it objectively deserves, then one should also expect a negative reaction against it.
 
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  • #18
atyy
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String theory is not "a" theory. It is the theory. :P
 
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  • #19
Demystifier
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String theory is not "a" theory. It is the theory. :P
It is not the theory of everything. It is the theory of anything. :biggrin:
 
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  • #20
stevendaryl
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Seems more like the string religion. No predictions, not that much evidence, and no apparent way to observe something 50 orders of magnitude that small. I mean considering it seems almost impossible to observe something on the 10^-32 meter magnitude, it seems even more impossible to observe something as small as a string. There's no good reason to believe that string theory is true at all. Its ambiguity and unfalsifiability make it equivalent to Yahweh or whatever. It also seems like there are way to many different versions of string theory, which makes it seem like the different sects of Christianity. I guess it does have one prediction though--a multiverse.

Just as an aside, I don't think that there is any good served by comparing science that people think is deficient in some way (falsifiability, usually) to religion. It has nothing in common with religion. The comparison is simply being insulting.
 
  • #21
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Are Newton's laws of motion falsifiable? I would say they are not. They become falsifiable when you add a specific hypothesis as to the nature of the forces involved in a particular problem. But in the absence of the knowledge of what forces might be relevant, to say that force is proportional to acceleration is consistent with absolutely any motion. Newton's laws are a framework that can be used to form a falsifiable theory, but it isn't a falsifiable theory in itself.

String theory is the same way. It's a framework within which someone can form a falsifiable theory, but it isn't a falsifiable theory in itself. I think early on, there was hope among string theorists that string theory might make unique predictions about such things as strengths of coupling constants, and so forth, but later it was found that there were many possibilities, and that it didn't seem to make unique predictions. That doesn't make it useless as a theory, but it means that to be a falsifiable theory, you have to add additional assumptions, beyond the basic framework of everything being strings.

Falsifiability is certainly important, but people shouldn't make a religion out of it. :wink:
 
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  • #22
Ben Niehoff
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Are Newton's laws of motion falsifiable? I would say they are not. They become falsifiable when you add a specific hypothesis as to the nature of the forces involved in a particular problem. But in the absence of the knowledge of what forces might be relevant, to say that force is proportional to acceleration is consistent with absolutely any motion. Newton's laws are a framework that can be used to form a falsifiable theory, but it isn't a falsifiable theory in itself.

Same goes for "energy". It's happened over and over again: Study some system in detail and find that energy seems to be lost? Just postulate a new kind of energy! Now energy is just changing form.

"Energy is conserved" is more or less a tautology; it only requires that you define energy appropriately.
 
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  • #23
Haelfix
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Apologies this is veering off into metaphysics, but there is another sociological danger with too much reliance on 'falsifiability' and that is what is known as lamp post physics.
The analogy goes as follows:

Suppose you were looking for the proverbial needle in the haystack and you knew it was located somewhere in a dark street. Now at some point in time a street light would turn on, illuminating a small portion of the street. I could make a theory (or a set of theories) describing in detail how the needle (or set of needles) happened to be right where the light would illuminate. A perfectly sound, falsifiable idea.

But in the absence of any other reason to be there, my theory has no new information content even though I have now given myself some percentage of chance for having correctly described the situation (and winning an award). Meanwhile the idea that the needle might be closer to the seamstress's house seems to be a better idea, although of course it is completely unfalsifiable (b/c it stays in the dark).
 
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  • #24
marcus
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To make sense in this kind of discussion I think you need some concrete examples of testable (BtSM) theories for comparison. This may be helpful:

http://arxiv.org/abs/1510.08766
Observational Exclusion of a Consistent Quantum Cosmological Scenario
Boris Bolliet, Aurelien Barrau, Julien Grain, Susanne Schander
(Submitted on 29 Oct 2015)
It is often argued that inflation erases all the information about what took place before it started. Quantum gravity, relevant in the Planck era, seems therefore mostly impossible to probe with cosmological observations. In general, only very ad hocscenarios or hyper fine-tuned initial conditions can lead to observationally testable theories. Here we consider a well-defined and well motivated candidate quantum cosmology model that predicts inflation. Using the most recent observational constraints on the cosmic microwave background B modes, we show that the model is excluded for all its parameter space, without any tuning. Some important consequences are drawn for the deformed algebra approach to loop quantum cosmology. We emphasize that neither loop quantum cosmology in general nor loop quantum gravity are disfavored by this study but their falsifiability is established.
5 pages, 1 figure
 
  • #25
Haelfix
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So the above paper Marcus linked to is an example of what I was talking about earlier
Sometimes a subset of a given theories parameter space outputs a model with testable consequences, but other parts of that space are not verifiable thus nonverification of the former simply entails exclusion limits.

In this case a particular model of Loop Quantum Cosmology is falsified. The authors explain:
"It is important to underline that only a very specific version of LQC is excluded: a universe filled with a massive scalar field, treated in the deformed algebra approach, with initial conditions set in the remote past before the bounce, no backreation, no anisotropies and no cutoff scale"

An example of something like this in particle physics might be the possible exclusion of the constrained minimal supersymmetric standard model (the CMSSM) which is under great duress by recent LHC data. An example from string theory model building which will be tested very soon would be say, this recent work by Gordon Kane and collaborators:
http://arxiv.org/abs/1408.1961

All of these are examples of specific models which are constructed such that their predictions would be testable, and are subsets of much more general frameworks. They are all basically examples of lamppost physics.
 
  • #26
haushofer
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Apologies this is veering off into metaphysics, but there is another sociological danger with too much reliance on 'falsifiability' and that is what is known as lamp post physics.
The analogy goes as follows:

Suppose you were looking for the proverbial needle in the haystack and you knew it was located somewhere in a dark street. Now at some point in time a street light would turn on, illuminating a small portion of the street. I could make a theory (or a set of theories) describing in detail how the needle (or set of needles) happened to be right where the light would illuminate. A perfectly sound, falsifiable idea.

But in the absence of any other reason to be there, my theory has no new information content even though I have now given myself some percentage of chance for having correctly described the situation (and winning an award). Meanwhile the idea that the needle might be closer to the seamstress's house seems to be a better idea, although of course it is completely unfalsifiable (b/c it stays in the dark).
Don't apologize. These are important questions for physicist. Otherwise we are just sophisticated bookkeepers :P
 
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  • #27
Demystifier
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Same goes for "energy". It's happened over and over again: Study some system in detail and find that energy seems to be lost? Just postulate a new kind of energy! Now energy is just changing form.

"Energy is conserved" is more or less a tautology; it only requires that you define energy appropriately.
A good example is general relativity. There, energy-momentum tensor of matter does not obey global conservation. But then one invents an ugly non-covariant object called energy-momentum pseudo-tensor, which does obey global conservation.

There is also a much cheaper way to resolve the problem of conserved energy-momentum in GR
http://lanl.arxiv.org/abs/1407.8028
but physicists object that it is too useless.

Sorry for the off-topic, but I couldn't resist. :sorry:
 
  • #28
Demystifier
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Don't apologize. These are important questions for physicist. Otherwise we are just sophisticated bookkeepers :P
Or to paraphrase Rutherford, otherwise physicists risk to become stamp collectors.
 
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  • #29
marcus
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All of these are examples of specific models which are constructed such that their predictions would be testable, and are subsets of much more general frameworks. They are all basically examples of lamppost physics.

You would dismiss this as "lamppost physics"? :

http://arxiv.org/abs/1509.05693
Detailed analysis of the predictions of loop quantum cosmology for the primordial power spectra
Ivan Agullo, Noah A. Morris
(Submitted on 18 Sep 2015)
We provide an exhaustive numerical exploration of the predictions of loop quantum cosmology (LQC) with a post-bounce phase of inflation for the primordial power spectrum of scalar and tensor perturbations. We extend previous analysis by characterizing the phenomenologically relevant parameter space and by constraining it using observations. Furthermore, we characterize the shape of LQC-corrections to observable quantities across this parameter space. Our analysis provides a framework to contrast more accurately the theory with forthcoming polarization data, and it also paves the road for the computation of other observables beyond the power spectra, such as non-Gaussianity.
24 pages, 5 figures
 
  • #30
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Hm ... was quantum theory derived from a well-defined set of general principles and assumptions in the first place? When I look at the history it rather seems that it was extended ad-hoc in some step-by-step manner.
This was the initial situation. Later it has become a theory. The papers of Heisenberg and Schrödinger, together with the Born rule which clarified that the wave function defines the probability have transformed this vague old "quantum theory" into a real physical theory.

I don't know string theory good enough to judge if it has already reached such a level, but all what I have heard indicates that it has not yet reached this state.
 
  • #31
Smattering
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This was the initial situation. Later it has become a theory. The papers of Heisenberg and Schrödinger, together with the Born rule which clarified that the wave function defines the probability have transformed this vague old "quantum theory" into a real physical theory.

That's true. But you cannot change the original derivation of something at a later point in time. If a result was originally derived in a certain way, that will will stay the way it was originally derived until the end of time. It might turn out that there are additional ways to derive the same result, but that does not change the original derivation.
 
  • #32
Ilja
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That's true. But you cannot change the original derivation of something at a later point in time. If a result was originally derived in a certain way, that will will stay the way it was originally derived until the end of time. It might turn out that there are additional ways to derive the same result, but that does not change the original derivation.
No. Results about planets have been derived a long time using Newtonian mechanics. Then GR came, and after this all what we think about planets has been rederived based on GR. This will happen again if some better theory of gravity will be found.

The same holds, of course, for quantum results. What has been derived in old quantum "theory" has been rederived later based on quantum theory as we use it today.

And, given that many quantum results are only approximate, they are recomputed all the time if a better approximation method or simply a more powerful computer or computation program appears. And in all these cases, the former derivation are no longer interesting except for history.
 
  • #33
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No. Results about planets have been derived a long time using Newtonian mechanics. Then GR came, and after this all what we think about planets has been rederived based on GR. This will happen again if some better theory of gravity will be found.

The same holds, of course, for quantum results. What has been derived in old quantum "theory" has been rederived later based on quantum theory as we use it today.

And, given that many quantum results are only approximate, they are recomputed all the time if a better approximation method or simply a more powerful computer or computation program appears. And in all these cases, the former derivation are no longer interesting except for history.

If the result changes, then we are not speaking of rederivation anymore.

You can rederive the same results as many times as you want: The rederivation never becomes the original derivation.
 
  • #34
marcus
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Video of the talks to be given at next week's conference on issues like these will be available free on line (according to the organizers)
http://www.whytrustatheory2015.philosophie.uni-muenchen.de/program/index.html
===quote==
Monday (7 December)
Time Topic
09:30 - 09:50 Opening
09:50 - 10:30 David Gross: What is a Theory?
10:30 - 11:10 Carlo Rovelli: Has Theoretical Fundamental Physics become Sterile?
11:10 - 11:35 Coffee Break
11:35 - 12:15 Richard Dawid: Non-empirical Confirmation
12:15 - 12:55 Massimo Pigliucci: Post-empirical Physics, Falsificationism, and the Public Perception of Science
12:55 - 14:35 Lunch
14:35 - 15:15 Radin Dardashti: Physics without Experiments?
15:15 - 15:55 Helge Kragh: Fundamental Theories and Epistemic Shifts: Can History of Science serve as a Guide?
15:55 - 16:35 Peter Achinstein: Scientific Speculation
16:35 - 17:00 Coffee Break
17:00 - 18:30 Panel I (Host: Stephan Hartmann): Why Trust a Theory?
Tuesday (8 December)
Time Topic
09:30 - 10:10 Björn Malte Schäfer: Dark Gravity, Dark Fluids, and Dark Statistics
10:10 - 10:50 Chris Smeenk: Gaining Access
10:50 - 11:20 Coffee Break
11:20 - 12:00 Gordon Kane: String/M-Theories about our World are Testable in the Traditional Physics Way
12:00 - 12:40 Joseph Silk: The Limits of Cosmology, Post-Planck
12:40 - 14:30 Lunch
14:30 - 15:10 Fernando Quevedo: Achievements and Challenges for String
Phenomenology/Cosmology

15:10 - 15:50 Chris Wüthrich: Considering the Role of Information Theory in
Fundamental Physics

15:50 - 16:30 Viatcheslav Mukhanov: Is the Quantum Origin of Galaxies Falsifiable?
16:30 - 17:00 Coffee Break
17:00 - 18:30 Panel II (Host: Johanna Erdmenger): How far do we get with Empirical Data?
19:15 Dinner (Cafe Reitschule)
Wednesday (9 December)
Time Topic
09:30 - 10:10 George Ellis: Limits in testing the Multiverse
10:10 - 10:50 Joseph Polchinski: String Theory to the Rescue
10:50 - 11:20 Coffee Break
11:20 - 12:00 Elena Castellani: Scientific Methodology: A View from Early String Theory
12:00 - 12:40 Dieter Lüst: Aspects of Quantum Gravity
12:40 - 14:30 Lunch
14:30 - 15:10 Sabine Hossenfelder: Lost in Math
15:10 - 15:50 Karim Thebault: What can we learn from Analogue Experiments?
15:50 - 16:30 Georgi Dvali: Secret Quantum Lives of Black Holes and Dark Energy
16:30 - 17:00 Coffee Break
17:00 - 18:30 Panel III (Host: Daniele Oriti): Has Physics changed? – and should it?
Abstracts
...
...

[endquote]
 
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  • #35
marcus
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Sample abstracts of some of the talks to be given at the conference:
==quote==
Massimo Pigliucci: Post-empirical Physics, Falsificationism, and the Public Perception of Science
Trouble, as explicitly hinted at in the title of a recent book by Lee Smolin, has been brewing for a while within the fundamental physics community. Ideas such as string theory and the multiverse have been both vehemently defended as sound science and widely criticized for being “not even wrong,” in the title of another book, by Peter Woit. Recently, George Ellis and Joe Silk have written a prominent op-ed piece in Nature, inviting their colleagues to defend the very integrity of physics. To which cosmologist Sean Carroll has responded that physics doesn’t need "the falsifiability police,” referring to the famous (and often misunderstood or badly applied) concept introduced by Karl Popper to demarcate science from pseudoscience. The debate isn’t just “for the heart and soul” of physics, it has spilled onto social media, newspapers and public radio. What is at stake is the public credibility of physics in particular and of science more generally — especially in an era of widespread science denial (of evolution and anthropogenic climate change) and rampant pseudoscience (antivax movement). Since philosophers of science have been invoked by both sides, it is time to take a look at the “physics wars” from a detached philosophical perspective, in my case informed also by my former career as an evolutionary biologist, a field that has peculiar similarities with what is going on in fundamental physics, both in terms of strong internal disputes and of perception by a significant portion of the general public.

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.

George Ellis: Limits in testing the Multiverse
Our ability to test cosmological models is severely constrained by visual horizons on the one hand, and physical horizons (limits on testing physical theories) on the other. Various arguments have been given to get round these limitations. I will argue that these amount to philosophical choices, which may or may not correspond to physical reality, and hence resulting claims do not amount to established scientific results. This holds in particular to a variety of claims of physical existence of infinities of galaxies, universes, or beings like ourselves in a multiverse. We need a strong philosophical stance to distinguish which of these claims should indeed be regarded as proven science,and which not.

Carlo Rovelli: Has Theoretical Fundamental Physics become Sterile?
Fundamental physics has changed from a field capable of spectacular successful predictions (electromagnetic waves, black holes, antiparticles, just to name a few...) to a depressing sequence of failed predictions: low-energy supersymmetry being the most recent and burning. Why? I will consider the possibility that the last generation of theoretical physicists has modified the practice of scientific method. Unproductively.
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