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Test for String Theory Developed
inexion writes "PhyOrg is reporting that SLAC (Stanford Linear Accelerator Center) scientists have found a way to test the revolutionary theory, which posits that there are 10 or 11 dimensions in our universe. This past December, Joanne Hewett, Thomas Rizzo, and student Ben Lillie published an article in Physical Review Letters which shows theoretically how to measure the number of dimensions that comprise the universe. By determining how many dimensions exist, Hewett and Rizzo hope to either confirm or repudiate string theory under specific conditions which would consist of creating and examining 'micro-black holes', which could be formed by smashing two high energy protons together. Using the predicted decay properties of the emitted neutrinos, Hewett and Rizzo solved equations to find that our universe may have more than 10 or 11 dimensions -- too many dimensions to be explained by string theory."
How many micro-black holes have we measured in a lab?
None.
How many micro-black holes have we even seen?
None, as it turns out.
This is a story of hope and speculation--much like the story of super string theory.
Hell, do we even have the capabilities to smash two high energy protons together?
To be fair, Bosonic Super string theory has room for 25 dimensions but it's flawed with tachyon, the so called imaginary mass.
I'd be interested to know how they intend to measure the micro-black holes.
My work here is dung.
"Black Holes in Many Dimensions at the CERN Large Hadron Collider: Testing Critical String Theory" JoAnne L. Hewett, Ben Lillie, and Thomas G. Rizzo Phys. Rev. Lett. 95, 261603 (2005)
For those with access to PRL, the doi for the paper is: 10.1103/PhysRevLett.95.261603
This is the abstract: For those without access to PRL, you can view a different version of the manuscript on arXiv.
My comments (with the usual disclaimer: while I am a scientist, I'm not a particle physicist/string theorist, so I would appreciate any corrections to what I say): This work appears significant. String theory is incredibly elegant and fits in very well with other (experimentally verified) theories (quantum field theory, etc.). However, what string theory has always lacked, is experimental backup. The fact that there may be a way to experimentally test one of its predictions/requirements (that of extra dimensions) is truly significant, and will allow these fundamental theories to be advanced way beyond their current speculative nature.
As I understand it, one of the current "problems" in string theory is an over-abundance of theories. There are millions (perhaps even an infinite number) of theory-variants that are all consistent with the current string-theory formalism. Of course only one (or possibly zero) of the theories is right. An experimental test would (I hope!) help pick out which theory variant is the right one... or perhaps tell us that string theory is completely wrong! Either way it's a good thing for science and I look forward to this test being performed at the LHC.
Evolutionary "theory," for example, has a substantial quantity of data that suggests the general notion is true. But string theory, at least in the scientific community, does not maintain the same support that most other "theories" have. There are, rather, a number of prominent physisists who believe string "theory" doesn't deserve the theoretical status it has obtained (or at least that's what I've been led to believe).
The question I have, therefore, how was the "theory" part conferred?
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> but golly gee whiz, what happens if the the mini black holes don't behave quite exactly like they're supposed to?
Given 11 dimensions to work with, it will be easier to kiss your ass good-bye.
Sheesh, evil *and* a jerk. -- Jade
That when they find out that String Theory is String Fact, they'll find out that the string was placed there to keep the nano-kittens occupied.
Task Mangler
How is string supposed to predict the amount of dimensions? Do they drop it in a black hole and see how far it goes, and use it from that?
Sincerely, Confused in the Fifteenth Dimension
Grammar Nazi
My work here is dung.
You may not believe this, but the English language is often ambiguous. Some words have two, three, four, or more meanings. The word theory is one of those. One definition of theory is a widely tested and accepted set of principles, as in Einstein's theory of relativity, which gives specific predictions about the universe that have been time and again proven correct to a high degree of accuracy. Another definition of theory is a hypothesis that has not yet been verified, as in string theory, which has not been scientifically verified at all. Yes, this ambiguity causes no end of confusion when one refers to the "theory of evolution". Many of us sit back and chuckle as people refer to it as "just a theory".
What a fool believes, he sees, no wise man has the power to reason away.
Since when have we been able to create micro-black holes? Man.....screw lightsabers, i want a gun that shoots micro-black holes!
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All black holes emit Hawking radiation, which is essentially black-body radiation (the object is trying to come into thermal equilibrium with the rest of the universe, so is emitting/absorbing radiation to do so). The origin of Hawking radiation is vacuum pair production, if anyone is interested. This radiation causes the black-hole to slowly "evaporate." The temperature (hence rate of evaporation) is inversely proportional to the black-hole mass (hence size).
Micro-black-holes are (obviously) very small. Thus, they evaporate very, very quickly. In fact, they are well below the sustainable threshold, and will evaporate much faster than they accumulate new mass. Also note that these micro-black-holes have quite low mass, hence their graviational attraction is pretty much nill. They are "black holes" because their mass density is infinite, and they are thus a singularity, but nothing about "black holes" definitely implies "consumes matter indefinitely" (this only happens for black holes of sufficient size).
So, no, there is no danger with micro-black-holes eating up the entire Earth. Yes, our current theories may be incorrent (you never know), but if micro-black-holes were able to grow without bound, then you'd expect the universe to be littered with black holes all over the place (which is not the case). Thus there's no reason to worry: the LHC will not gobble up the Earth.
From Wikipedia: "String theory is a model of fundamental physics whose building blocks are one-dimensional extended objects (strings) rather than the zero-dimensional points (particles) that are the basis of the Standard Model of particle physics..."
y
Here is the article:http://en.wikipedia.org/wiki/String_theor
Sun and Fun
It is a theory in the mathematical sense similar to Group Theory, Set Theory, or Ring Theory. In mathematics these "theories" really refer to the specific set of axioms assumed. There exist some axioms (well, really, assumptions) that define the body of work that is "string theory". But one should not confuse string theory for mathematics. There are few rigorous proofs in the literature, a very large set of assumptions, and a large set of unproven conjectures.
In practice, unless a very bizarre set of miracles occur (such as the fundamental scale of gravity being much, much lower than we measure it to be -- such as is assumed in the article), there is no way we will ever conclusively prove string theory to be correct. It will always be possible to write down a different theory which gives the same physics, but is far simpler. String theory is not falsifiable and therefore is unlikely to stand the test of time. (or, maybe, it will live forever -- kind of like dragons and vampires)
-- Bob
1^2=1; (-1)^2=1; 1^2=(-1)^2; 1=-1; 1=0.
>how was the "theory" part conferred?
There is no governing body that certifies theories. Saying something is a theroy does not specify how certain it is, how close it is to the "truth", how popular it is, how accepted it is within a group, how does it compare to other theories, how close it is being falsified. "Being worthy of academic discussion" is another idea.
(Some people would be scared because of this, saying that it makes science weak. But it doesn't, because science is about being open to ideas and exploring them, which means that everything is open, even to "crazy ideas" like string theory which should be evaluated and proven/disproven by its merits along, not on some title given by a set of people.)
The surprise isn't how often we make bad choices; the surprise is how seldom they defeat us.
One should really call it String Hypothesis or String Postulate.
In cases like this, untested ideas about the function of the universe, I personally like the term "model." You can use it to posit the inner workings of the universe and why things happen, but untill the technology is there and the experiments have been run it is not fully a scientific theory. But I believe it does fall within the bounds of model. And the nice thing about this is that with a model, you can make some assumptions that may or may not be true to simply explore how the world would work supposing this is true.
My favorite correlary is light. We have a model of light behaving as a wave, and that model has been proven to be wrong under certain cirumstances. We have a model of light behaving as a particle, and that model can also be proven wrong under certain circumstances. However, the fact that each model is not completely correct does not mean that they are useless. The basis of the model can be used to make further predictions about the way the world works, or even to produce technology through engineering.
I'll never make that mistake again, reading the experts' opinions. - Feynman
If one day string theory is validated by an actual experiment what consequences will it have for the various interpretations of Quantum Mechanics? Is it going to give more credibility to any one of the interpretations of QM? Or is this a completely orthogonal issue?
Disclaimer: I know nothing about String Theory but methinks that a true Theory of Everything must provide us with an unambiguous answer for the nature of the collapse of a wavefunction, no?
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Peter Woit, a critic of string theory, points out some of the misleading bits in this article on his blog, "Not Even Wrong: http://www.math.columbia.edu/~woit/wordpress (scroll down for it). A brief discussion of why this isn't quite as exciting as it may sound.
JoAnne Hewett (one of the original authors) also comments in the blog, saying that the journalists tried to make the work a little more accessible by suppressing important details: As for the headline that is blazened on the SLAC home page - I saw it for the first time when someone drew my attention to it. I knew it was going to cause headaches...
So while this may be solid work, it doesn't seem quite so sexy as it has been made out to be...
Yes, but will string theory prevent Xbox 360s from overheating?
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> isnt anything that is purported to be true as a result of some a mathematical proof a theorem and something that is known to be true but has no proof a postulate(Law)?
Notice that "theory" and "theorem" are different words. Theorems arise from applying rules of inferences to sets of axioms (and previously proven theorems).
In general, the empirical sciences work by induction and hypothesis testing rather than by applying rules of inference to known truths, and thus don't produce theorems.
As others have pointed, there are several meanings of the word "theory", even in the world of science. I don't know the history of it, but I suspect "string theory" is called a theory because of its very mathematical nature, like "computational complexity theory".
Also, I suspect we will continue to call it "string theory" even if it is eventually shown to be wrong.
I'm not crazy about that choice of names for it - we don't have any problems naming GR or QM without putting "theory" in the name - but language and terminology seem to have lives of their own.
Sheesh, evil *and* a jerk. -- Jade
>> By determining how many dimensions exist, Hewett and Rizzo hope to either confirm or repudiate string theory
You cannot confirm a theory.
An experiment can either support it or disprove ("repudiate") it.
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Yeah, there's nothing wrong with guestimated probability, or an understanding of the universe based on an uneducated perception. Hell, what's the worst that could happen, anyway? Tho', who among us would recognize a micro-black-hole if we saw one ...?
Oh, well. I hereby declare micro-singularities safe! As far as we know. Er, have observed. Which isn't much. At all, really. So ... um ... good luck.
Boom.
(Incidentally, I "expect" this post to merrily go completely unnoticed and acquire a total score of 0.)
You'd think they'd leave this stuff alone after the "incident" over at the Black Mesa Facility. I think 4 dimensions is plenty for us right now.
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In that case, this also fits the theory of evolution. Evolution attempts to explain the past, but what predictions does it make of the future than could be checked out by experiment?
You are joking, right? The Theory of Evolution does not "attempt to explain the past" - it attempts to explain how one can get from point A to a later point B. We just happen to have mostly developed and verified the theory by looking at As and Bs that are in the past.
When one has access to an overwhelming amount of past evidence that can be compared against, one doesn't need to wait the 10s of millions of years necessary to see if it happens again.
That anyone doubts the truth of Evolution anymore I see as an astonishing failure of the school system.
one doesn't need to wait the 10s of millions of years necessary to see if it happens again.
The drawback of only having historical data is that there are quite a few holes in that data (IOW the sampling rate is rather low).
Using this data we don't get to see evolution in action, we see only the end result of what we assume/theorize must be evolution.
So in this case, yes we would benefit from 'seeing if it happens again'.
The main point is that there are many "ifs", "ands", and "buts" in the paper that did not make it into the news release. Essentially what we showed was that, in a very special set of circumstances it is possible to make a measurement at the LHC which will could possibly determine the number of extra dimensions. If that can be done, then the result will be very important to understanding string theory, since the number of dimensions plays an important role in that theory. It certainly can not rule out string theory. We think it's an important and interesting piece of work, but it isn't a definitive "test" of string theory, as the headline suggests.
Here is a comment JoAnne left on Peter Woit's blog when this showed up there, and the complaint was raised that the story sounded over-hyped:
I've also replaced the arxive version with the published version: http://arxiv.org/abs/hep-ph/0503178, so both versions should now be the same.
Ben Lillie
Hello - this is my work. It has been misrepresented and blown out of proportion and I am quite upset about this. The asterisk means that there are many technical if's, and's, or but's of our analysis which are not explained in the news story. It means that our analysis applies to models of extra dimensions where micro-blackholes can be formed with a size less than the curvature of the additional dimensions and where the fundamental particles which make up our universe do not reside in the extra dimensions. These micro-blackholes must also exist at an energy scale which can be probed at the Large Hadron Collider. Under those, very specific, conditions our test holds. These conditions are possible within string theory, but need not be present.
He's the paper's author, and he's modded at one right now.
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