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Is String Theory Really a Scientific Theory?
vk38 writes, "The New Yorker is running a story on whether String Theory is really a scientific theory or just an abstract exercise in math designed to churn out papers and Ph.Ds for the established academics. The article reviews two current books, by Lee Smolin and Peter Woit, laying out the case against string theory."
From the article: "Dozens of string-theory conferences have been held, hundreds of new Ph.D.s have been minted, and thousands of papers have been written. Yet... not a single new testable prediction has been made, not a single theoretical puzzle has been solved. In fact, there is no theory so far — just a set of hunches and calculations suggesting that a theory might exist. And, even if it does, this theory will come in such a bewildering number of versions that it will be of no practical use: a Theory of Nothing... String theory has always had a few vocal skeptics... Sheldon Glashow, who won a Nobel Prize for making one of the last great advances in physics before the beginning of the string-theory era, has likened string theory to a 'new version of medieval theology,' and campaigned to keep string theorists out of his own department at Harvard. (He failed.)"
I am a geek, but I have seriously problems with math ability. I have a Bachelor of Arts degree. However, I like to keep up on math and science news as much as possible, inasmuch as I can understand it.
IIRC, string theory *does* make predictions, but the amount of energy required to run an experiement would be literally almost astronomical, so we have no practical way of testing it. I think according to concensus on what the 'scientific method' is, that makes it a hypothesis -- an educated guess, based on evidence. After it has sucessfully passed a few rounds of experiment, then we can say that it is a theory.
So, bottom line, it is scientific, as much as any other hypothesis. However, it's not a theory.
Computers are useless. They can only give you answers.
-- Pablo Picasso
the problem is that those predictions are currently beyond our experimental powers. i believe the most near-term prediction could be supported if supersymmetric particles are observed at the large hadron collider when it's completed.
It seems that a lot of confusion can be cleared up by remembering the definition of theory. From the wiki:
This post climbed Mt. Washington.
You can read about him on Wikipedia, if you like.
Ben Hocking
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Wow, this post was so amazingly wrong....
As others pointed out 'theory' doesn't mean 'guess.'
The word you're searching for is hypothesis. Here's how it works:
1) Data
2) Hypothesis that explains current data
3) Prediction derived from Hypothesis
4) Data from new tests
5) See if hypothesis matches #4 data
6) Repeat, then hypothesis is called theory
So, if something can not be tested by going through that process, it is just a hypothesis looking for a way to become a theory. Atomic theory has gone this way too, there was always a theory that explained current data, and had some predictive power. These models eventually failed as new tests were made. Therefore new hypothesizes needed to be created.... This is the scientific process.
Having a "rolled up" dimension doesn't require an extra dimension, because they're not _actually_ rolled up. The metric used to describe them is just easy to picture that way. Just like curved 4-dimensional space time doesn't need a 5th dimension to be curved into. I tried looking for a good web-site that explains this, but didn't find one in the time I'm willing to spend looking for one. I'm sure someone else knows of one, though.
Ben Hocking
Need a professional organizer?
Not only is there no way to test string theory at the moment, string theorists cannot even concieve of a way to test it in the future. As others have stated, the only tests people have thought of involve energy levels similar to that of the entire universe, to effect a change on an atomic scale.
So we have a "theory" that doesn't make any predictions, and cannot be tested. In that way it is very similar to "Intelligent Design" which also doesn't make any predictions, and cannot be tested. If ID isn't science, why is string theory?
Here's the problem though. GR and QM are both, relative to ST, extremely simple. And while ST may make the same predictions that GR and QM make, it does so in a far more complex way, without adding any extra information -- QM and GR are incompatible, but ST fails to resolve those incompatibilities in a testable way.
GR was more complex than Classical Newtonian Mechanics, but it was, essentially, a value-added theory: it explained a bunch of things that Classical Mechanics couldn't, all while remaining compatible with Classical Mechanics in places where Classical Mechanics made accurate predictions. Therefore, GR was taken to replace classical mechanics, despite the added complexity of the theory, because it was broader in scope, falsifiable, and provably more correct than the theory it replaced.
ST does not fit this mold. It is far, far, far, far more complex than either GR or QM, and makes no extra falsifiable predictions. It doesn't resolve the inconsistencies between the two. In other words, from a purely scientific perspective, it's just a hypothesis and not a particularly useful one at that.
Of course, I'm a mathematician by training and lots of interesting math has come out of ST, so for that I'm happy.
The problem is, if string theory was WRITTEN to the other theories, to describe what is happening and mathematically manipulated to come up with the same results, then it is not a theory.
If it were a theory, then string theory could independantly create a new testable hypothesis (that may be backed up by current quantum theory or relativity) and be tested based on merits of its own. Something is not a scientific theory if it merely describes what has already happened and can make no new predictions outside of that sphere. Even if the predictions were WRONG then it would still have been a theory. The world has had people creating explanations for already observed behavior for thousands of years, some have been called religions, others philosophy etc... but most didnt actually meet the criteria of being testable or (in the case of religions especially) falsifiable.
If you don't vote, you don't matter, so don't waste your time telling me your opinion
First of all it is no surprise that it resembles QM because it is QM. It assumes QM and applies it to a vibrating string, brane, etc.. But there is no new theory because there's at least a handful of different ways to do this and they're all called string theory. GR on the other hand is not as obvious. They are able to get equations that resemble Einstein's equations, but GR does NOT just pop out of it.
I read Smolen's book recently, and learned a lot of new and interesting things about string theory from it. Some problems with string theory:
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Should the New Yorker not cover things that may be beyond the reach of the average reader?
Even if they were publishing the mathematical theory itself, they should be free to do so (though it would probably not appeal to the average reader), but they're not doing that, they're publishing about a controversy in the field - just as they might about any other field. Is physics somehow different than (to take an example from one article I remember) considering the effectiveness of different kinds of therapy on people who've experienced stressful events and who might then be subject to PTSD?
Writers and journalists should be encouraged to write about whatever interests them and their audience, even if the people they're writing about don't always find it flattering or helpful.
As someone who frequently reads the New Yorker, I must say I've learned a lot from it over the years - and in many areas that I'm not familiar with such readings have sometimes taught me something (perhaps only a little, but something), sometimes aroused my curiousity, and sometimes introduced me to whole new ideas that I might not have otherwise run into. I say "More power to 'em".
This is why you don't get it: That is behaviour which is generally considered unscientific. If you need to keep modifying your theory to explain stuff, then it's not a scientific theory. It's an ad-hoc mess of empiricism of zero real value. The rules of the game are:
1) It must be testable (falsifiable)
2) You must provide new predictions
3) You must explain previous observations, observations not used in formulating the theory., and ideally, none at all.
4) You must do so using fewer postulates (assumptions) than the previous theory.
The word you're looking for is "model". But how is this another thing? Our current understanding is a model as well. The question is whether it's a better model or not is still there and unanswered.
You have no clue. Modern chemistry is not based on any such model. It's based entirely on the standard model of physics. There is not one, not one! molecular property that can be described in anything less than a fully quantum-mechanical treatment. All of chemistry is purely due to quantum-mechanical effects.
And string theory is not the same at all, even if you'd been right. String theory is an attempt at a more basic and general theory of quantum mechanics, in the same way as classical mechanics is a limiting case of quantum theory. It is not an approximation of quantum theory, and not intended to be one.
You don't get it. The periodic table is already entirely explained from QM, and has been for some time. There's no more reason to describe it in terms of string theory than to describe the motion of billiard balls in terms of quantum mechanics: It's unnecessary because it's already explained by classical mech, and we know classical mech is a subset of quantum mech.
In the case of string theory, all they need to do is show that QM is a subset of that theory. That's not hard and it is. It forms the basic premise of their work as well as the goal. The idea is that they're going to work from part of quantum theory and relativity and somehow arrive at the whole thing. Which parts the