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Evidence for String Theory?
Posted by
CowboyNeal
on Sat Jan 28, 2006 09:22 AM
from the quarks-and-stuff dept.
from the quarks-and-stuff dept.
Izeickl writes "PhysOrg.com is reporting that scientists working at a neutrino detector nicknamed AMANDA at the South Pole report that evidence for string theory may soon be coming. Extra dimensions predicted by string theory may affect observed numbers of certain neutrinos and this is what the scientists will be looking for. The article further states 'No more than a dozen high-energy neutrinos have been detected so far. However, the current detection rate and energy range indicate that AMANDA's larger successor, called IceCube, now under construction, could provide the first evidence for string theory and other theories that attempt to build upon our current understanding of the universe.'"
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Fundamental Constant Possibly Inconsistent 317 comments
dylanduck writes "Cosmologists have begun thinking that yet another fundamental constant of nature is, er, not constant. The constant in question is the ratio of a proton's mass to that of an electron. It governs the strong nuclear force but there's no explanation for why that ratio should be constant. If true it would provide support for string theory, which predicts extra spatial dimensions." From the article: "Researchers at the Free University in Amsterdam in the Netherlands and the European Southern Observatory in Chile discovered the variation in mu. They did it by comparing the spectrum of molecular hydrogen gas in the laboratory to what it was in quasars 12 billion light years away. The spectrum depends on the relative masses of protons and electrons in the molecule."
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new dimensions (Score:5, Funny)
sounds suspiciously like... (Score:3, Funny)
Re:new dimensions (Score:5, Funny)
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Re:new dimensions (Score:4, Funny)
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Re:new dimensions (Score:3, Funny)
I'll pass.
well is it (Score:2, Insightful)
Re:well is it (Score:2, Interesting)
Re:well is it (Score:3, Interesting)
Re:well is it (Score:5, Insightful)
That's the big, important, difference.
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Re:well is it (Score:2)
If nobody has any idea on how to even begin to falsify it, what's the difference?
>>Religion is by definition not falsifiable.
String theory by construction is unfalsifiable.
Re:well is it (Score:2)
Re:well is it (Score:2)
Re:well is it (Score:4, Informative)
Parent
Re:well is it (Score:3, Insightful)
It's a huge difference. But beyond that, if a theory/model makes predictions about how the universe works, and it is impossible to ever prove it wrong (falsifiable), by definition you've just demonstrated that it is a perfect model of the universe. That is, after all, the goal of the Theory of Everything, to have a model that explains and can predict everything.
Religion is not falsifiable because it makes no predictions
Re:well is it (Score:5, Interesting)
No, that really IS the case [sfgate.com] from a lot of physicists' POVs.
One problem with the theory is that according one physicist's paper, string theory offers 10 to 500th power different universes all with different physical properties and with many different kinds of forces. String theory practioners -- dare I say worshippers -- use this to say that our universe is merely one out of 10 to the 500th power different possible universes. Some flakes, like Michio Kaku, think we can colonize a new universe through a wormhole with light-speed traveling single-atom nanobots containing the technological and cultural seeds of a new civilization to avoid the heat death of our own universe. [sfgate.com] (This article is why I'll never respect Michio Kaku's words ever again. How did this man ever get a reputation for understanding physics?)
Other physicists rightly point out that if they theory can handle an almost uncountable number of alternate universes with alternate sets of forces and physical constants, then it doesn't actually predict anything useful since you can't figure out how to predict anything about our own specific single universe has and that its not falsifiable because any new observations we find can be retrofitted into the theory by playing with and changing the math as has happened numerous times since the theory's inception.
Of course, string theory may be right. The philosophical problem is that many of our best minds are spending all their time on a theory that can't be proven or disproven with current technology. Some of the experiments needed to confirm or deny string theory will take super-colliders capable of generating energy on a scale far beyond even a type I civilizaions' resources (the theoretical energy densities needed to tear matter down to its component strings).
Since its practioners frequently disdain the necessity of experimental verification, since it's useless as a predictive tool, and since it can be retrofitted for any information that conflicts with it that we'll be able to achieve in the forseeable future, string theory is for all practical purposes nothing more than a math-based religion.
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Falsifiable (Score:3, Interesting)
If you find internal consistency (within the dogma of a religion, including their trusted documents) and external consistency with the outer (earth/cosmos) and inner (conscience/mind) world, then you can start taking it seriously.
Ordinary Christianity has its share of mystery and hyper-rational statements (that is, statements that seem to be bey
Re:Falsifiable (Score:5, Insightful)
No seriously. The filter you propose wouldn't even catch the travesty that was epicycles. There's a reason why Occam's razor is such an integral part of scientific philosophy.
[/flamebait]
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Re:Falsifiable (Score:5, Funny)
Yeah, I especially liked the part where Jesus went around hiding dinosaur bones to test our faith. He's such a scamp that Jesus.
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Re:Falsifiable (Score:3, Interesting)
Uh oh... (Score:5, Funny)
Re:Uh oh... (Score:3, Funny)
South Pole (Score:2, Funny)
Don't get your hopes up (Score:5, Informative)
Normally, string physics is thought to appear at the Planck scale (far beyond what we will ever be able to probe directly), because that is thought to be the size of the "curled up" extra dimensions. However, it's possible that the dimensions aren't actually that small, that they could be much larger — possibly not much smaller than a millimeter. (They could even be infinitely large, not curled up at all, and we could be living on a 4-dimensional "brane" close to another one.) In those cases, stringy behavior is brought down from the Planck scale to as low as 1 TeV (tera-electron volt), which is the energy that corresponds to a distance somewhat below a millimeter. (By the Uncertainty Principle, higher energies correspond to shorter distances that can be probed.)
The problem is, there isn't a lot of reason to believe that these scenarios ought to be true; they are highly speculative (even relative to string theory as a whole!). To a large extent, they are just hopeful thinking — that stringy physics might occur at in an energy regime we can probe. They could be helpful in understanding the hierarchy problem (the question of whether and why there is an absence of new particles between the electroweak and Planck scales), but when you get down to it, most high energy physicists are not betting on large extra dimensions. So these experiments might very well not show up any evidence of string theory (even if string theory is true).
Re:Don't get your hopes up (Score:2)
Re:Don't get your hopes up (Score:5, Informative)
Actually there is a good, theoretical, reason to think that these "Large Extra Dimension" (LED) scenarios might be correct (though I'll only believe it if we get data to back it up). If LEDs do exist they can solve the problem that the Standard Model of particle physics has explaining the huge difference in energy scales between the Planck scale (10^16 GeV) and the electroweak scale (10^2 GeV).
If LEDs exist then gravity might become a lot stronger above the ~TeV energy scale i.e. the Planck scale is actually ~10^3-4 GeV and not 10^16 GeV and a lower energy scales we are fooled into thinking gravity is a lot weaker simply because we can't see these extra dimensions where it spends a lot of its time.
The problem that LEDs have is in explaining proton decay. It is very likely that protons do in fact decay (this is linked to the fact that we only see protons and no anti-protons in the Universe) but with an incredibly long lifetime caused by the very high energy of the Planck scale. If you lower this energy to a few TeV you either end up with rapidly decaying protons (bad!) or having to put a conserved symmetry in which prevents all proton decay (also bad!).
So LEDs are an interesting theory which could solve some real problems with existing theory at the cost of introducing some new problems of their own. As a result I think Supersymmetry (which solves the problem which LEDs answer as well as the missing dark matter problem) is a better bet but I'll only believe it if we see it! Unfortunately from an experimentalists point of view LEDs would be a far more interesting discovery since it would mean we could start doing quantum gravity experimentally before the theorists have figured it all out....but not knowing exactly what you'll find is part of the fun of physics!
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Re:Don't get your hopes up (Score:3, Funny)
Who needs evidence? (Score:5, Insightful)
Actually, this is really cool. Looking forward to what the use of the new detector shows, or doesn't, as the case may be. String theory is such a mind bender for most people (including me), that anything making it more directly tangible will really help focus the conversation. Or end it. Either way is good.
This sounds familiar (Score:3, Funny)
You may know him from (Score:5, Funny)
Also seen in such blockbuster hits as Boyz n the Nucleus, Three Quarks, and xXx: State of the Quantum.
That's nice, but. . . (Score:5, Insightful)
Re:That's nice, but. . . (Score:3, Insightful)
We can take three cases. First, the flat earth. On a small scale, the earth seems flat, and in every day life we treat it so. The success of this theory is shown by out upstanding building and bridges. The problem occurs when we try to assume that local flatness is universal.
Conversation at the South Pole (Score:5, Funny)
Peon: We've counted 12 possible events out of 789,567,345,754,234,567,876 (est) neutrinos passing thru the detector.
TS: Hmm, that's as expected, totally useless number of events to draw any inferences from. Keep at it.
(Next day) South Pole Grant Administrator: Hey, TS, got any news I can tell Washington? Your grant approval comittee meeting for the Big Project is next week!
TS: Oh, yes, Er, Um, hte data we got from their previous infusion of cash indicates Big Things, the possible proff of String Theory, SuperGravity, The AntiMacassar Postulate, and much more. But better just mention String Theory to the commitee, it was on the cover of Popular Science last month.
SPGA: Will do!
Actually (Score:2, Interesting)
I think you were joking, but astrophysicists extracted a surprising amount of information [arxiv.org] from the 19 neutrinos observed from Supernova 1987A.
Heim theory? (Score:4, Interesting)
Sigh (Score:5, Interesting)
The fact is, pretty much nobody knows what the hell Heim theory predicts. Most of his theory was never published or reviewed by his peers. We don't even know if his theory is self-consistent, whether the predictions hyped by New Scientist or the Internet "Heim appreciation society" that's pushing it are actually predictions of the theory, etc. For that matter, hardly anybody knows what the definition of the theory is.
Just because some people have made a bunch of wild claims about what Heim theory can predict, doesn't mean it's something to get excited about. Nor does Heim's reputation. Schroedinger himself thought he had come up with a unified field theory, called a big press conference, privately spoke of winning a second Nobel Prize. Some reporter asked Einstein what he thought, and he responded with a carefully worded response to the effect that one shouldn't get the impression that physics is like unstable Third World dictatorships, always experiencing revolutions. Schroedinger's theory didn't pan out and the two stopped corresponding for over a year.
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Re:Sigh (Score:5, Interesting)
Now, there is NO paper or source code available which does this. Hermetism, no thank you, this is the strongest indicator that its simply bunk.
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I already have proof of String Theory (Score:3, Funny)
See "Not Even Wrong" Blog (Score:3, Informative)
http://www.math.columbia.edu/~woit/wordpress/?p=33 5 [columbia.edu]
A snippet of which is:
The half a dozen references to string theory in the short press release might lead the gullible to think that we're about to be provided with evidence for the "exotic predictions of string theory", but that has little relationship to the reality here, one aspect of which of course is that there are no "predictions of string theory" about any of this.
A qualified No. (Score:5, Interesting)
The only interesting thing about this experiment is that it could very well rule out the existence of extra dimensions at the energies which the LHC will begin to probe in a year or two even before the LHC comes on line. And yes, I am a string theorist.
predictions, evidence, and testing hypotheses (Score:3, Insightful)
For example, my hypothesis might be that Donald Trump's social security number is 666-66-6666. Now, I conduct an experiment in which I test the prediction that his social security number is not 123-45-6789 and the experiment succeeds. I have gotten a tiny bit of evidence for my original hypothesis, but it's so small as to be negligible.
Well, with scientific theories, it's even worse because there are not just 1 billion of them but an infinite number--unless you do things exactly right, a successful prediction gives you no evidence for a scientific theory at all.
Some comments from an Amandroid... (Score:5, Informative)
I work for AMANDA/IceCube. It's nice to see that our supercool experiment gets media attention, but there are a few statements in that article which need a comment or two. User davidoff404 [slashdot.org] already commented [slashdot.org] on the theoretical aspects of the article, so I will mostly limit myself to the experimental aspects.
Actually, we see about 900 neutrino events per year. Their directions are homogeneously distributed over the sky and the energy spectrum is (still) compatible with the assumption that all these neutrinos were produced in interactions of high energy cosmic rays (protons, nuclei) with the Earth atmosphere (all around the globe). It might be that there are neutrinos among them from extraterrestrial sources, but individual events cannot be identified as such. We continue taking data until neutrino events from single extraterrestrial sources (or with higher energy than expected from atmospheric neutrinos) pile up enough such that they stick out over the atmospheric neutrino background.
Note: we do not detect those neutrinos directly; they interact with the ice, and may convert into a "muon" (which is like an electron, only about 200 times heavier, and it decays after a little while). That muon still carries most of the neutrino's energy with it, so it flies practically with the speed of light through the ice, sending out Cherenkov light (the electromagnetic equivalent of a sonic boom) along the way. The tracks can be kilometers long. We only see the part of the track in or near our detector, so we can only estimate a lower limit of the energy of an individual muon. When the neutrino does not convert into a muon, then the energy is dissipated in a relatively small volume; which makes it much harder to estimate the direction, but easier to estimate the energy.
(And of course those atmospheric neutrinos are not only background. We are happy to see them, as they prove that our detector is not blind. And we can use them to test the models of cosmic ray spectra and to study properties of neutrinos themselves.)
Actually, neutrinos are so weakly interacting that the vast majority of them just flies right through the Earth. It is really tiny fraction of them which happens to bump into an terrestrial atom. And an even tinier fraction which bumps into an ice molecule near our machine. So they come from all directions, up and down, the Earth is not shielding them. However, like everywhere on Earth there is a lot of cosmic rays thundering down on the atmosphere above the South Pole, and some of it results in high energy muons which make it all the way down to our detector. Their rate is about a million times higher than that of the muons originating from the neutrinos. Only when we see a muon track going upwards, or when it has an energy much higher than expected from the cosmic ray spectrum, then we call it a neutrino event.
When we start talking about really very high energy neutrinos (PeV and more) then the picture gets a little bit different: at those energies the probability that a neutrino interacts with atoms gets so high that the Earth is indeed opaque for neutrinos. If there are such high energy neutrinos flying through the universe, then we expect to see them from above and horizontally. This is already expected with standard model physics, without assumptions about microscopic black holes; so I am curious as to what Goldberg and Feng are after.
Re:Now we know.. (Score:3, Informative)
http://en.wikipedia.org/wiki/Heim_theory [wikipedia.org]
Predictions of faster tan light travel (amoung other things)
Re:Now we know.. (Score:5, Funny)
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Re:Neutrino Detector at the South Pole? (Score:5, Informative)
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Re:Neutrino Detector at the South Pole? (Score:4, Informative)
Now if a neutrino causes a shower of cherenkow radiations, it can be detected many many meters away.
So instead of building huge watertanks in deep mines, one can use the deeper ice layers as a large detector.
You just melt holes into it and put photodetectors in a grid pattern, and get billions of tons of detector mass (which you need because low chance of neutrino interaction with matter)
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Re:Neutrino Detector at the South Pole? (Score:5, Funny)
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Re:wake me when this matters to us 3d people (Score:4, Insightful)
I'm confused by this one. There's an onward march of socialism? I thought it fascism
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Re:wake me when this matters to us 3d people (Score:5, Interesting)
You essentially ask: what use is fundamental physics research?
You can't ever predict what applications fundamental research will have on technology. Sometimes, things are immediate: after Roengten discovered X-rays in 1895, the medical application was obvious. On the other hand, in 1905 Einstein predicted that objects moving fast experience time dilation relative to stationary objects. In 1915 he also predicted that the same would hold for objects higher up in a gravitational well. This was completely irrelevant to then-current technology: Nothing man-made moved faster than 500mph, or got high enough off the ground, and anyway time couldn't be measured accurately enough for these effects to matter. Swing around to the 1980s. The US government is now launching the GPS system, which depends on exteremly precise timing synchronization between a satellite in orbit and the unit on the ground. It turns out that the two relativistic time-dilation effects have to be taken into account for the system to work at all. Who'd have thunk this in 1915?
Moreover, progress is usually incremental. No single discovery will "cure HIV" or give us infinite energy. New physics beyond the standard model might have technological applications in 80 years. Does that mean we shouldn't discover it today?
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Re:wake me when this matters to us 3d people (Score:3, Informative)
Re:wake me when this matters to us 3d people (Score:3, Interesting)
Socialism? I thought that stopped decades ago...
I find one potential use for those extra dimensions - a place where emotions, ghosts and the whole paranormal zoo can reside. There's quite a bit of stuff there which has no space whatsoever in Newton or Einstein style universes, but which people routinely relate to in a more or less systematic way. Would be nice to have a rational explanation for this stuff :)