You call that a prediction? Yes.
Seems like my job here is done. Nice way to declare yourself correct even when your basic claim was proven wrong. It's not a string theory paper, yet it gives a test of a prediction of string theory.
Again, string theory says that space is absolutely not continuous, it's discrete. You can not *infinitely* subdivide an interval, and particles are not perfect, literally *zero size* mathematical points. String theory does have continuous space, and it says that strings are perfect curves of zero thickness.
String theory places limits on how small you can measure something, however, since you have to use strings to do it; esssentially, you can't measure something that is smaller than the strings you're using to probe it. So there is sort of a "fuzzy" minimum effective distance, even though space itself is continuous.
The only way string theory could be tested is if it could actually make a prediction that can be put to a test. Unfortunately, it can't predict how fast a ball will fall from the top of the Leaning Tower of Pisa. Neither can Newton's theory of gravity. Unless you put in the value of the gravitational constant by hand, that is. And if you do that, then string theory can predict it just as well as Newton's theory of gravity, since the former reduces to the latter in the classical, weak field, slow motion limit.
As I said, the paper is not specific to string theory and makes no calculations within the context of string theory. It gives tests of any generic theory that obeys unitarity, analyticity, Lorentz invariance, and crossing. That includes both string theory and quantum field theory as subsets. So no, it is not a string theory paper: it is more general than that. But it does have implications for string theory.
Try reading the paper yourself. You would save yourself less embarrassment that way.
String theory can't even spit out a single number that we can compare with experiment. Neither can quantum field theory.
Of course, specific models constructed within the framework of QFT can make detailed predictions. But then, so can models constructed within string theory.
Yes, it does give such predictions. Read your own link. The paper is not specific to string theory; the predictions of string theory which can be falsified using the described means would also falsify relativistic quantum field theory. But they would falsify string theory.
We already have a pretty convincing mathematical understanding of electromagnetic fields and waves, and how energy travels in this form. So the first thing that strikes me whenever I read about this string theory is that they're talking about "strings of energy". But they're not. You can write down non-critical string theories in which the "strings" are really flux tubes of, say, electromagnetic fields. But that's not the kind of string being discussed, which is a real physical object with mass, tension, etc.
If by chance string theory happens to line up with physical reality for a bit, I think it's likely for the same reason as it did before with chemical elements. Coincidence. You haven't made an actual argument for how string theory is related to Kelvin's knot picture of atoms. You can't reason by analogy because the two have nothing in common. You could equally well say that string theory is related to the successful gauge theory picture of flux tubes and therefore string theory is likely to succeed on those grounds. (And that analogy actually has the virtue that gauge theory really is mathematically related to string theory.) You could, with an even closer analogy, say that string theory is gauge theory and you would be right, at least for certain gauge theories, and therefore infer the success of string theory on the basis of the success of gauge theory. That would be far more meaningful than vaguely referencing an aether vortex theory of atoms.
You can't adjust the dimensionality of string theory to "make it work". The dimensionality of string theory is not an adjustable free parameter.
Furthermore, most major unified theories has included extra dimensions in one way or another (see here). (One except was Einstein's failed 4D theory with non-symmetric connection.) It appears important to have extra dimensions in order for unification to take place. If that's your goal, then you probably need extra dimensions, string theory or not.
No, the very first version of string theory came about to explain the strong interaction (not quantum gravity), then it was abandoned, then they picked it up again because of the spin 2 bonus... That's true, but it turned out that string theory isn't a theory of the strong interaction and is a theory of quantum gravity. My point is that, unlike epicycles, string theory was not constructed to be a complicated phenomenological fit to arbitrary data.
You forgot to mention the part where this "unique" theory generates 10^500 possible universes. No, I didn't "forget" to mention it. My point was that you can't adjust string theory itself to suit your needs — there is only one string theory.
Note, too, that there are far more than 10^500 possible quantum field theories; even if you restrict yourself to the ones that are compatible with known physics, there are still infinitely many.
Please tell me one prediction that can FALSIFY string theory; This very story gives such predictions.
not experiments that confirm predictions made in the "low energy limit". Standard model is plenty good enough for the low energy limit, thank you very much. Yeah, that's why they built the LHC — to confirm the Standard Model. Sheesh.
You can have the weird little string theories in 6 dimensions, and non-critical strings in less than 10. Critical superstring theory lives in 10 dimensions, and M-theory lives in 11 dimensions. Critical bosonic string theory lives in 26 dimensions, although that doesn't contain any fermion particles and hence doesn't describe our universe, unless it turns out to be related nonperturbatively to M-theory in some unknown way.
Wow, a theory totally unrelated to modern string theory was once disproved, and you "predict" that string theory will also be disproved for similar reasons.
News at 11: phlogiston disproved, therefore string theory is wrong.
This whole story is about testing predictions of certain string models. However, we can't presently test predictions of all string models at once, and thus rule out all of string theory. Shame on me for not RTFA. The story is about testing all string models at once. However, the tests of are a very general sort (e.g., "do probabilities add up to 1") so, with the possible exception of Lorentz invariance (obeying special relativity at all scales), even non-string theorists would not bet highly on violations being seen.
Which string theory? There's a few. Anyone who says "M-Theory" will get slapped. All of them. (And "M-theory" is a perfectly legitimate answer; you can't escape the fact that all the string "theories" are really just different regions of solution space of the same theory.)
What predictions does the string theory in question make? In this case, unitarity, analyticity, Lorentz invariance, and crossing. (Or rather, that all those properties are obeyed to arbitrarily high energies.)
Are the predictions unique to string theory? No, they're also axioms of standard relativistic quantum field theories.
If anyone cares to read a highly technical discussion of the paper by its first author (Jacques Distler), you can read his blog entries and the accompanying comments here and here.
Yes, those assumptions are also shared by standard quantum field theory. (You can write down Lorentz-violating quantum field theories though.) So you're right, if those turn out to be wrong it's a bigger deal than just ruining string theory.
Everyone always seems eager to compare to epicycles any modern physics theory they don't care for. String theory, dark matter, what have you...
Physicists were led to string theory in a search for a consistent theory of quantum gravity, not in a search to make up the most complicated theory possible to fudge arbitrary data. For more on why string theory should be taken seriously as a solution to this problem, you can read a long analysis in a previous post of mine here. String theory itself cannot be modified to "fit" to a model; it is a unique theory with no adjustable parameters or interactions. However, you can construct various string models to fit observations, as you can presently using quantum field theory models like the Standard Model.
It is also not correct that string theory doesn't make testable predictions. This whole story is about testing predictions of certain string models. However, we can't presently test predictions of all string models at once, and thus rule out all of string theory. But then, the same is true of quantum field theory models as well; there are infinitely many such models that could be true but which we can't yet test.
String theory always seemed to be the most complicated mathematical way you could "force" a unified field theory into existence by adding as many dimensions and undefinable, physically meaningless constants as possible. Actually, it's the simplest known way of creating a unified field theory.
It's been known since the 1920s that adding extra spacetime dimensions allows you to unify forces; Kaluza and Klein successfully unified classical electromagnetism and gravity that way, with a theory in 5 spacetime dimensions. Unfortunately, this idea can't be readily extended to all the forces in the Standard Model, and the unified theory is at least as difficult to quantize as gravity alone.
From a different perspective, leaving gravity out of it, there are the grand unified theories. They too have "extra dimensions", except that the extra dimensions are not of spacetime, but of an internal "gauge" symmetry space. (Kaluza-Klein theory basically turns these internal gauge dimensions into true space dimensions, paving the way to a gravitational theory.)
String theory also does not add as many "undefinable, physically meaningless constants as possible". Indeed, it has fewer constants than the Standard Model. In fact, it has only one constant, which is certaintly definable: it is the string tension. Furthermore, the dynamics of string theory are unique, unlike the quantum field theories. (You can write down infinitely many different particle physics theories with different particle content and interactions, but all of the string theories are part of the same theory, and all the strings obey the same fundamental laws of interaction.)
In short, string theory is not a totally contrived fudge; pretty much all of the ideas that led to semi-successful unified field theories found their way into string theory in a natural and uniquely determined way.
The most fundamentally interesting research in AI is in the humanoid robotics projects such as those at the MIT shop, and it is from these more humanly-modeled projects that anything like HAL could ever issue. Search-digest heuristics like PAL aren't much like humans and will never lead to anything approching a human's contextually rich understanding of the world at large It is far from clear whether "humanoid robotics" are either necessary or useful in producing AI with a "contextually rich understanding of the world at large".
The planes are a strong indicator that the "rings" in ice core samples cannot be used for dating. Like I asked before, what do the planes have to do with the reliability of ice core samples? Note, again, that they don't take ice core samples from active glaciers.
To be fair, paleoclimate temperature reconstructions are much fuzzier data than planetary ephemerides, in terms of the sizes of their relative error bars.
Actually the danes determined it was the cosmic ray flux that affected the cloud formation rather than variances in solar intensity. Clouds are far more important that co2 in temp. effects. The role of cosmic rays in cloud formation is far from established, and while clouds are important, global warming is not significantly attributable to variations in cloud cover. Cloud formation plays more of a role in prediction of future events, not attribution of past warming.
I'm well aware of the weather girls reference to decertification. It's the same thing - shutting up people who don't subscribe to your doctrines. No, it's asking media figures to not pose as experts in a field in which they are not expert, which is a reasonable thing for them do if they want their professional society to endorse their job.
As for food sources which produce less methane - well - from what I understand of vegetarians - they simply replace cows in producing it. People do not produce as much methane as cows, and you don't even have to be vegetarian — there are meat sources that also produce far less methane than cows.
except for the popular media who recently announced that bovines were responsible for more gcg effects than mankind's entire transportation system. What you continue to ignore is that bovine contributions to overall global warming are still considerably less than mankind's overall contribution.
Global warming is far superior to an iceage. False dichotomy. Global warming is not staving off the next ice age, not over the next couple centuries at least.
It looks like we are at the trailing end of an unusual warming trend which has lasted far longer than average. The current warming is far more than any natural warming trend, and no, the time since the last ice age is not unusually long as far as interglacial periods go.
I don't plan on getting involved in any climatic research as it interests me relatively little so I don't expect to discover any fudged data until the scandal makes the news media. Then you will refrain from accusing climate scientists of fudging data in Slashdot debates, then, correct?
My argument is that you can't take fuzzy data, drill it out to 5 decimal points, and suddenly claim it's precise data because your computer model goes out to that many significant digits. Nobody claims that the data is precise to 5 decimal points, nor does it need to be in order to make conclusions about climate trends today compared to the past.
What you can't do honestly, however, is take that data, and then assert that 2006 was the "hottest year" in 10,000 or 100,000 years. AND THIS IS WHAT MANY GLOBAL WARMING PUNDITS ARE CLAIMING. They are wrong in claiming that 2006 is the hottest year in 10,000 years; you can't reconstruct individual yearly temperatures that far back. However, if you take decadal averages, then there is much stronger evidence that, say, the last 20 years have been hotter than any other comparable 20-year period over thousands of years.
It really helps when you try to be precise about what you yourself are claiming. It is not B.S. to claim that we can reconstruct temperatures 10,000 years ago. It is B.S. to claim that we can reconstruct them "to 5 decimal points" or whatnot.
Slashdot Mirror
String theory places limits on how small you can measure something, however, since you have to use strings to do it; esssentially, you can't measure something that is smaller than the strings you're using to probe it. So there is sort of a "fuzzy" minimum effective distance, even though space itself is continuous.
Wikipedia is right. I dropped a factor of 2 in the formula R = 2GM/c^2.
As I said, the paper is not specific to string theory and makes no calculations within the context of string theory. It gives tests of any generic theory that obeys unitarity, analyticity, Lorentz invariance, and crossing. That includes both string theory and quantum field theory as subsets. So no, it is not a string theory paper: it is more general than that. But it does have implications for string theory.
Try reading the paper yourself. You would save yourself less embarrassment that way.
Einstein's four dimensions are 3 dimensions of space + 1 dimension of time, as the grandparent post noted.
Of course, specific models constructed within the framework of QFT can make detailed predictions. But then, so can models constructed within string theory.
Yes, it does give such predictions. Read your own link. The paper is not specific to string theory; the predictions of string theory which can be falsified using the described means would also falsify relativistic quantum field theory. But they would falsify string theory.
You can't adjust the dimensionality of string theory to "make it work". The dimensionality of string theory is not an adjustable free parameter.
Furthermore, most major unified theories has included extra dimensions in one way or another (see here). (One except was Einstein's failed 4D theory with non-symmetric connection.) It appears important to have extra dimensions in order for unification to take place. If that's your goal, then you probably need extra dimensions, string theory or not.
Note, too, that there are far more than 10^500 possible quantum field theories; even if you restrict yourself to the ones that are compatible with known physics, there are still infinitely many. Please tell me one prediction that can FALSIFY string theory; This very story gives such predictions. not experiments that confirm predictions made in the "low energy limit". Standard model is plenty good enough for the low energy limit, thank you very much. Yeah, that's why they built the LHC — to confirm the Standard Model. Sheesh.
You can have the weird little string theories in 6 dimensions, and non-critical strings in less than 10. Critical superstring theory lives in 10 dimensions, and M-theory lives in 11 dimensions. Critical bosonic string theory lives in 26 dimensions, although that doesn't contain any fermion particles and hence doesn't describe our universe, unless it turns out to be related nonperturbatively to M-theory in some unknown way.
Wow, a theory totally unrelated to modern string theory was once disproved, and you "predict" that string theory will also be disproved for similar reasons.
News at 11: phlogiston disproved, therefore string theory is wrong.
A centimeter-sized black hole would be as massive as the Earth itself. (The Earth's Schwarzschild radius is 0.5 cm.)
If anyone cares to read a highly technical discussion of the paper by its first author (Jacques Distler), you can read his blog entries and the accompanying comments here and here.
Yes, those assumptions are also shared by standard quantum field theory. (You can write down Lorentz-violating quantum field theories though.) So you're right, if those turn out to be wrong it's a bigger deal than just ruining string theory.
Everyone always seems eager to compare to epicycles any modern physics theory they don't care for. String theory, dark matter, what have you...
Physicists were led to string theory in a search for a consistent theory of quantum gravity, not in a search to make up the most complicated theory possible to fudge arbitrary data. For more on why string theory should be taken seriously as a solution to this problem, you can read a long analysis in a previous post of mine here. String theory itself cannot be modified to "fit" to a model; it is a unique theory with no adjustable parameters or interactions. However, you can construct various string models to fit observations, as you can presently using quantum field theory models like the Standard Model.
It is also not correct that string theory doesn't make testable predictions. This whole story is about testing predictions of certain string models. However, we can't presently test predictions of all string models at once, and thus rule out all of string theory. But then, the same is true of quantum field theory models as well; there are infinitely many such models that could be true but which we can't yet test.
It's been known since the 1920s that adding extra spacetime dimensions allows you to unify forces; Kaluza and Klein successfully unified classical electromagnetism and gravity that way, with a theory in 5 spacetime dimensions. Unfortunately, this idea can't be readily extended to all the forces in the Standard Model, and the unified theory is at least as difficult to quantize as gravity alone.
From a different perspective, leaving gravity out of it, there are the grand unified theories. They too have "extra dimensions", except that the extra dimensions are not of spacetime, but of an internal "gauge" symmetry space. (Kaluza-Klein theory basically turns these internal gauge dimensions into true space dimensions, paving the way to a gravitational theory.)
String theory also does not add as many "undefinable, physically meaningless constants as possible". Indeed, it has fewer constants than the Standard Model. In fact, it has only one constant, which is certaintly definable: it is the string tension. Furthermore, the dynamics of string theory are unique, unlike the quantum field theories. (You can write down infinitely many different particle physics theories with different particle content and interactions, but all of the string theories are part of the same theory, and all the strings obey the same fundamental laws of interaction.)
In short, string theory is not a totally contrived fudge; pretty much all of the ideas that led to semi-successful unified field theories found their way into string theory in a natural and uniquely determined way.
To be fair, paleoclimate temperature reconstructions are much fuzzier data than planetary ephemerides, in terms of the sizes of their relative error bars.
It really helps when you try to be precise about what you yourself are claiming. It is not B.S. to claim that we can reconstruct temperatures 10,000 years ago. It is B.S. to claim that we can reconstruct them "to 5 decimal points" or whatnot.