Alright, I don't want to get too down into the weeds here. From the Wikipedia--- "No experimental verification or falsification of the theory has yet been possible" The experiment being discussed here is a possible falsification of the theory, if it were to be performed.
I have no problem with modifying the models, but extraordinary claims require extraordinary proof. They don't have it. Nobody is claiming to have proof of string theory. What is your point?
I recall a string theorist friend of mine a few years back telling me that people hadn't even been able to derive actions from it yet, much less equations of motion. I don't know what that could refer to. You can certainly right down actions for perturbative string theory in general, and you can also derive all manner of low-energy effective field theory actions from specific models, including ones that look like the Standard Model. (Or rather, more like a supersymmetric version of the Standard Model.)
Yeah, heaven forbid someone who reads a site run by mainstream climatologists in order to find out what climatologists are saying. (P.S. RealClimate is not Mann's site; he is just one of the contributors.)
While consensus does not "make science", it is representative of the opinions of most of the experts in a field. Thus, if you want to find out what "the climate community's" best judgement on an issue, you look for the consensus opinion, when it exists.
There is plenty of literature on solar forcing, and RealClimate does not discount it, they merely say that variations in solar forcing are not large enough to explain recent warming, particularly in the last 50 years. Note that the solar output during this period is measured and known.
One of the most notable instance is were that weather channel chick wanted to remove the membership/certification status for anyone who publicly disagreed with the official religion of global warming. Actually, as was pointed out to you in that thread, what she actually said was that certified TV weatherpeople have a responsibility to be informed about climate science, and that those who are not educated in climate science yet publicly make statements regarding the validity of climate science perhaps don't deserve certification. She said nothing, incidentally, about the membership or certification status of actual scientists, merely that of TV weatherpeople.
No, this work is not merely "applying a curve fit". He used solar data to infer the periodicity of resonant diffusion waves in the Sun. Some of those periodicities happen to match the periodicities found in ice age cycles; he didn't fit his theory to any paleoclimate data.
But does your theory explain the inferred periodicity in ice ages? Why should phytoplankton happen to start/end ice ages periodically at those particular times?
But come on. "The cycles predicted by Ehlrich's model line up with the observations." The summary says that like its some type of verification. They line up (duh) because he picked the cycles that way That's not true. The periodicity of the cycles in his models was determined from solar physics, not from paleoclimate observations. Yet those periodicities do match up with the observations. He didn't adjust them to make them fit the data; they worked out that way for independent reasons.
Quantum mechanics has not been proved to be deterministic. The abstract of the paper you cite does not give such a proof; it merely describes some mathematical properties that a deterministic theory of quantum mechanics ought to have. It also may be noted that pretty much no one else favors 't Hooft's ideas about deterministic quantum mechanics, including all the other Nobel physics laureates.
You're comparing string theory to some specific model like the Standard Model, when you should be comparing it to a framework like quantum field theory. If the Standard Model has problems, you just cook up a new QFT model that works. This is no different from string theory: if one string model is wrong, you make a new one. It's almost impossible to come up with an experiment that can disprove all possible string theory models at once, but the same is true for quantum field theory (and, in fact, the current story gives one general way of disproving either of them).
And for your information, string theorists do not modify string theory; they can't, because it is unique. They just switch to looking at a different solution of string theory (a different string model). (By contrast, those working within QFT have to switch to a different actual theory.) And they certainly don't "tack on a few more dimensions"; string theory doesn't allow you to adjust its dimensionality however you like.
It's hard to find much about Kelvin's ether vortex theory of atoms, but try here. It comes from an 1867 paper of his which may have been reprinted somewhere.
I don't think that any theory ever (with any kind of success) has been just dreamed up in an experimental vaccuum. Certainly not quantum mechanics. Certainly not string theory. Certainly not thermodynamics, nor Newtonian mechanics. Certainly not relativity, either general or special. Actually, Einstein worked fairly close to being in an experimental vacuum in many respects. People talk about the Michelson-Morley experiment, but with special relativity Einstein was primarily motivated to construct a mechanics whose transformation properties were mathematically consistent with Maxwell's equations. If you read through his general relativity papers, you see calculations here and there of various predictions, such as light deflection and orbital precession, but those calculations played virtually no role in his development of the theory itself; he came up with his various proposals on grounds like general covariance, assumptions about how gravity ought to mathematically couple to stress-energy, etc. and only after he had the theory did he bother to check it against anything.
Einstein was kind of unique in that way. He certainly was concerned with experiment, but it played unusually little role in the development of any of his ideas. String theory comes closest to approaching that (which isn't really a good thing), in that the modern string theory in its "theory of everything" form spent much of its development motivated reasons of pure mathematical consistency.
You can argue, though, that mathematical consistency is still at least indirectly connected to experiment since you're trying to be consistent with other theories which have been experimentally verified.
The prediction, which follows from the string theory assumptions, is that in WW scattering experiments, you will observe light resonances. If those resonances are not observed, you have falsified a prediction of string theory.
Technically, that doesn't give you uncountably many theories, just uncountably many solutions of the same theory. And note that you can write down uncountably many quantum field theories.
It is worth noting that GR doesn't really give us much of any predictions either. That's far from true. It has made plenty of very specific, tested predictions (see, e.g., here).
It makes some predictions for very very simple situations, Like static and spherically symmetric systems, which nonetheless give a wealth of specific predictions that other theories disagree with.
and it makes some extremely approximate predictions for some not so simple situations (like the entire universe). Which nonetheless agrees quite well with astrophysical observations (and not so approximate either; the universe is known to be homogeneous and isotropic on large scales, and you can handle the deviations accurately using perturbation theory).
No. String theory is a theory of quantum gravity. It is also a theory of quantum electromagnetism. It is also a theory of the quantum weak nuclear force. It is also a theory of the quantum strong nuclear force. I think you missed the context. String theory was originally conceived to be only a theory of the strong nuclear force. That non-critical, 4D string theory ended up losing out to quantum chromodynamics. Later, critical 10D string theory came along as a theory of quantum gravity and then a theory of everything. That's what I was saying: it didn't work out as a direct theory of the strong interaction, although the new quantum gravity version can incorporate to the strong interaction and other things in a very different way.
But, it nonetheless remains that string theory is a unified theory of all four fundamental interactions. Yes, I know.
Finally, the LHC was not built to "confirm the standard model". I know that too. I was being facetious in response to the other poster who claimed that the Standard Model is "good enough" for any low energy physics.
True, but seeing an unexpected new kind of particle is arguably more plausible than, say, violation of unitarity (which means that the probabilities of events don't add up to 1). You'd have to go very far outside of quantum theory to find a framework in which such a result makes sense.
It's not a great description. Its branching thing isn't really a 2D surface, it constantly appeals to lower dimensions as things that need to be embedded in higher dimensions in order to curve (not true), and it starts going badly wrong from there on (e.g., the fifth dimension in string theory is just a spatial dimension, not some set of personal quantum histories; likewise the sixth dimension is not a set of disconnected personal histories, it's just yet another a spatial dimension). I stopped watching at the seventh dimension, which was similarly unrelated to the dimensions of string theory.
Simple explanation: Traditional theories of physics hold that all matter is made up of tiny particles, which are geometric points of zero size. String theory holds instead that all matter is made up of tiny strings, which are just what they sound like.
As another poster noted somewhere in the comments, the explanation of dimensions on that site has little to do with dimensions as they are conceived in string theory.
I am not the string gestapo. I spent most of my graduate career working on alternative formulations of quantum gravity in direct opposition to string theory. I have simply pointed out that your arguments are wrong. Accusing me of bias is merely a cheap attack which fails to divert attention from the incorrectness of your claims.
Regarding Newton's equation: you can of course set G=c=1 in geometric units, but in order to make a prediction using Newton's equation that can be tested in an experiment, you do need to know the value of G in physical units (or at least GM). It is not true a priori that an object dropped near the surface of the Earth has to take 2 seconds to fall, say, 19.8 meters.
I forgot to reply to the rest of your post:
But on the other hand, the topological variations on extra dimensions and fluxes add up to 10^500 different theories with different predictions. How does that make an improvement over the twenty variables of the standard model? There are infinitely many different quantum field theories. The Standard Model is a particular theory, with a finite and relatively small number of free parameters. You can pick out specific models within string theory as well, with a finite and relatively small number of free parameters, including ones with the Standard Model embedded inside them. (They do tend to have more parameters than the Standard Model; they're more comparable to the Minimal Supersymmetric Standard Model in that respect.)
Really? Which? Does the mythical 'M-theory' exist other than as a big 'Maybe'? What does it look like? What predictions does it make? Substitute 'might be' for 'are' and add a 'conjectured' in front of 'theory'... No, "are" and "theory" are the correct words to use. The string theories are part of M-theory: it can be shown that they are all related non-perturbatively, even though we don't know what the full theory is. Because we can show that they are related in this way, we know that M-theory exists mathematically; it's an existence proof, not a constructive proof.
But there seems to be a lot of contrivance in there. Such as? String theory arguably makes fewer assumptions than quantum field theory. Where is the contrivance?
Then why don't they work in 3+1 dimensions? Because they have to work in 10+1 dimensions to get their theory to work, like I just said. That is a bizarre criticism. You claim that string theory has problems because the dimensionality has to be "adjusted" in order to "work". In fact, the dimensionality of string theory is not adjustable. It is the dimensionality of theories like general relativity and quantum field theory which are adjustable.
So what. I'm sure there was a time when most theories of the solar system included epicycles. Extra dimensions has never worked. Every new theory contains something that has never worked. Otherwise, it wouldn't be a new theory. That is no criticism of string theory either.
But there is always this excess mess that must be swept under the rug, like the scalar field and extra dimension of KK. One pushes the scalar field up to an extremely high energy by compactifying the extra dimension to be very small. Yes, and people have pushed the Higgs mass up to make it work, and that of the minimal supersymmetric partner, and you need to explain why you don't see an axion, and so on. Yet again there is nothing different in principle here than in other HEP model building.
There have been other ideas. I remember reading a paper by Ted Jacobson where he derived Einstein's equation from some thermodynamic principles and the existence of causal horizons. Yes, I know that paper well. It's one of the papers that got me interested in quantum gravity. However, it does not concern unification, which is what I was talking about (not quantum gravity).
Incidentally, the real implication of Jacobson's paper is not that Einstein's equation shouldn't be quantized, but rather that any reasonable quantization of gravity will yield Einstein's equations in the appropriate limit.
Even aside from this, there has long been some worry in the gravity community that the string/quantum theorists are trying to quantize the wrong theory. There is no reason to think that there really should be a graviton as there is a photon. In fact, there cannot be a fundamental graviton. However, generic consistency arguments mandate that any theory of quantum gravity must behave like gravitons at low energies. This is true in string theory, and loop quantum gravity people are trying to establish that it is true for their theory as well. In string theory, gravitons arise approximately as certain vibrational states of closed strings. In loop quantum gravity, it is hoped that gravitons appear as certain superpositions of spin network states.
It's not a theory but a collection of theories. The original five different-but-possibly-dual theories and handwaved 'M-theory', plus different flavours with added restrictions or extensions? No, it's one theory, with a collection of solutions that can be grouped by their behavior.
It's not by any means finished: for instance, finiteness hasn't been proven, and there is no explicit background independent formulation which yields GR spacetime? Finiteness hasn't been proven, but then, that hasn't been proven in realistic quantum field theory either, and nobody complains about that. (You can win a million dollars for proving it.)
There are background independent formulations of string theory, but none that give (4D, non-supersymmetric) GR in an obvious way. However, formal background independence is a matter of philosophical preference, not physical necessity.
The basic idea may seem simple, but is overlaid by a lot of kludges such as supersymmetry to eliminate tachyons and fluxes to get a positive cosmological constant? I wouldn't call adding supersymmetry to eliminate tachyons a "kludge", anymore than, say, adding gauge invariance in QFT to eliminate non-renormalizability. As for the positive cosmological constant, I'm not up to date on what is necessary to get that to work out in string theory, but all quantum theories have had notable problems explaining any realistic value of the cosmological constant.
Slashdot Mirror
"No experimental verification or falsification of the theory has yet been possible" The experiment being discussed here is a possible falsification of the theory, if it were to be performed. I have no problem with modifying the models, but extraordinary claims require extraordinary proof. They don't have it. Nobody is claiming to have proof of string theory. What is your point?
You're citing a creationist article? Give me a break.
Yeah, heaven forbid someone who reads a site run by mainstream climatologists in order to find out what climatologists are saying. (P.S. RealClimate is not Mann's site; he is just one of the contributors.)
While consensus does not "make science", it is representative of the opinions of most of the experts in a field. Thus, if you want to find out what "the climate community's" best judgement on an issue, you look for the consensus opinion, when it exists.
There is plenty of literature on solar forcing, and RealClimate does not discount it, they merely say that variations in solar forcing are not large enough to explain recent warming, particularly in the last 50 years. Note that the solar output during this period is measured and known.
No, this work is not merely "applying a curve fit". He used solar data to infer the periodicity of resonant diffusion waves in the Sun. Some of those periodicities happen to match the periodicities found in ice age cycles; he didn't fit his theory to any paleoclimate data.
But does your theory explain the inferred periodicity in ice ages? Why should phytoplankton happen to start/end ice ages periodically at those particular times?
"Solar Resonant Diffusion Waves as a Driver of Terrestrial Climate Change".
Quantum mechanics has not been proved to be deterministic. The abstract of the paper you cite does not give such a proof; it merely describes some mathematical properties that a deterministic theory of quantum mechanics ought to have. It also may be noted that pretty much no one else favors 't Hooft's ideas about deterministic quantum mechanics, including all the other Nobel physics laureates.
You're comparing string theory to some specific model like the Standard Model, when you should be comparing it to a framework like quantum field theory. If the Standard Model has problems, you just cook up a new QFT model that works. This is no different from string theory: if one string model is wrong, you make a new one. It's almost impossible to come up with an experiment that can disprove all possible string theory models at once, but the same is true for quantum field theory (and, in fact, the current story gives one general way of disproving either of them).
And for your information, string theorists do not modify string theory; they can't, because it is unique. They just switch to looking at a different solution of string theory (a different string model). (By contrast, those working within QFT have to switch to a different actual theory.) And they certainly don't "tack on a few more dimensions"; string theory doesn't allow you to adjust its dimensionality however you like.
It's hard to find much about Kelvin's ether vortex theory of atoms, but try here. It comes from an 1867 paper of his which may have been reprinted somewhere.
Einstein was kind of unique in that way. He certainly was concerned with experiment, but it played unusually little role in the development of any of his ideas. String theory comes closest to approaching that (which isn't really a good thing), in that the modern string theory in its "theory of everything" form spent much of its development motivated reasons of pure mathematical consistency.
You can argue, though, that mathematical consistency is still at least indirectly connected to experiment since you're trying to be consistent with other theories which have been experimentally verified.
The prediction, which follows from the string theory assumptions, is that in WW scattering experiments, you will observe light resonances. If those resonances are not observed, you have falsified a prediction of string theory.
Technically, that doesn't give you uncountably many theories, just uncountably many solutions of the same theory. And note that you can write down uncountably many quantum field theories.
True, but seeing an unexpected new kind of particle is arguably more plausible than, say, violation of unitarity (which means that the probabilities of events don't add up to 1). You'd have to go very far outside of quantum theory to find a framework in which such a result makes sense.
It's not a great description. Its branching thing isn't really a 2D surface, it constantly appeals to lower dimensions as things that need to be embedded in higher dimensions in order to curve (not true), and it starts going badly wrong from there on (e.g., the fifth dimension in string theory is just a spatial dimension, not some set of personal quantum histories; likewise the sixth dimension is not a set of disconnected personal histories, it's just yet another a spatial dimension). I stopped watching at the seventh dimension, which was similarly unrelated to the dimensions of string theory.
Simple explanation: Traditional theories of physics hold that all matter is made up of tiny particles, which are geometric points of zero size. String theory holds instead that all matter is made up of tiny strings, which are just what they sound like.
As another poster noted somewhere in the comments, the explanation of dimensions on that site has little to do with dimensions as they are conceived in string theory.
I am not the string gestapo. I spent most of my graduate career working on alternative formulations of quantum gravity in direct opposition to string theory. I have simply pointed out that your arguments are wrong. Accusing me of bias is merely a cheap attack which fails to divert attention from the incorrectness of your claims.
Regarding Newton's equation: you can of course set G=c=1 in geometric units, but in order to make a prediction using Newton's equation that can be tested in an experiment, you do need to know the value of G in physical units (or at least GM). It is not true a priori that an object dropped near the surface of the Earth has to take 2 seconds to fall, say, 19.8 meters.
Incidentally, the real implication of Jacobson's paper is not that Einstein's equation shouldn't be quantized, but rather that any reasonable quantization of gravity will yield Einstein's equations in the appropriate limit. Even aside from this, there has long been some worry in the gravity community that the string/quantum theorists are trying to quantize the wrong theory. There is no reason to think that there really should be a graviton as there is a photon. In fact, there cannot be a fundamental graviton. However, generic consistency arguments mandate that any theory of quantum gravity must behave like gravitons at low energies. This is true in string theory, and loop quantum gravity people are trying to establish that it is true for their theory as well. In string theory, gravitons arise approximately as certain vibrational states of closed strings. In loop quantum gravity, it is hoped that gravitons appear as certain superpositions of spin network states.
There are background independent formulations of string theory, but none that give (4D, non-supersymmetric) GR in an obvious way. However, formal background independence is a matter of philosophical preference, not physical necessity. The basic idea may seem simple, but is overlaid by a lot of kludges such as supersymmetry to eliminate tachyons and fluxes to get a positive cosmological constant? I wouldn't call adding supersymmetry to eliminate tachyons a "kludge", anymore than, say, adding gauge invariance in QFT to eliminate non-renormalizability. As for the positive cosmological constant, I'm not up to date on what is necessary to get that to work out in string theory, but all quantum theories have had notable problems explaining any realistic value of the cosmological constant.