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.)"

Comments

Neither Proved Nor Disproved

[eldavojohn]

String theory is a scientific theory that has neither been proved nor disproved to my knowledge.

I could speculate all day on whether or not it is fact but from what I've read, I will make a few statements. It seems that string theory was invented to satisfy some things we could not explain. This doesn't mean it's wrong or right although some people will contend that it is most probably wrong.

As the summary points out, few (if any) of String Theory's propositions can be tested or even observed. So it is simply an unknown right now. We cannot measure the proposed strings so how can we prove if they exist or they don't? We simply can't yet.

A good analogy would be Bohr's early assumptions about the atom. They were wrong but they were a step in the right direction. In hindsight, we see this now but we don't know what the future holds for String Theory. I'm just glad there are people out there thinking outside the box.

Do not fret, however, as scientists have been very resourceful at proving/disproving theories. I submit, for example, the exercise of determining the diameter of the building blocks of matter. Scientists had the idea to fill up one cubic milliletre of oil and dump it on top of a trough of water with a roller across the top. As the oil spread out, they moved the roller further down the trough. Once they started to see non-reflective parts of the water, they moved it back until they agreed the oil was completely spread out to the best of their abilities. Using this area, they determined how thick a molecule of oil could be without precision tools!

Similar ingenious tests have been devised to easily find the diameter of the earth at sunset on a beach with a yard stick or ruler.

So even though we may never be able to measure these strings, there are still some options left to explore to record properties that may prove/disprove their existence. We're merely in the very early stages of the scientific process.

Let us be excited about String Theory, even if it is wrong it sure is interesting. Nothing's wrong with a scientist who dreams, is there?

Re:Neither Proved Nor Disproved

[radtea]

String theory is a scientific theory that has neither been proved nor disproved to my knowledge.

What makes a theory scientific or not?

Falsifiability is only one criterion. Science is a communal activity, and to a far greater extent what is taken to be "scientific" is what is approved by the community. The community of science has a set of self-perpetuating rules such that we hope our communal sense of where the truth lies never gets too far out of sync with reality.

By the minimal standard of falsifiability string theory passes, just--there are experiments that can at least be imagined that would test the predictions of the large family of equations that string theory now encompasses. But it is a perfectly legitimate point that continuing to invest in a failed family of theories in perpetuity at some point becomes a faith-based initiative, and that divergent approaches should be more welcomed.

Insofar as aesthetics have played a role in physics, they have done so after the fact. The principles that guided most of the major developments in 20th century physics were consistency constraints with quite simple justifications. Most famously, Dirac's insistence on a second-order wave equation that treated space and time symmetrically gave us the foundations for relativistic quantum mechanics. This was not an arbitrary or aesthetic constraint, but a logical inference from empirical fact and known relativistic symmetries.

What string theorists are doing is quite different, and no amount of invoking Einstein or Dirac can hide that. If they want to be taken seriously they need to come up with "aesthetic" principles--if they want to call them that--that uniquely constrain their equations, perhaps up to a constant of integration (we gave Einstein that, after all.)

And until then, the measure of how "scientific" string theory is can be answered by a single question: How many string theorists are spending the majority of their time trying to prove that no string theory can ever describe the universe that we actually live in? If the answer to this question is: few or none, then the string theory community is not a scientific community, but merely a mutual admiration society.

Re:Neither Proved Nor Disproved

[wirelessbuzzers]

You're right: string theory is not a scientific theory. It's a mathematical theory. That is, it's a collection of mathematical axioms and related proofs (and an extremely unpleasant one, according to a physicist friend of mine).

String theory does provide a model of physics. That is to say, if you set the parameters right, you get something that looks kind of like quantum field theory (which, by the way, is also a mathematical theory in addition to a scientific one). Unfortunately, the math is too hard to deteremine how they differ, and even once a determination is made, string theory has a lot of parameters which will have to be set before real predections are possible. Note that quantum field theories are testable, but only barely. For instance, Howard Georgi's "representations of SU(5)" theory was disproved by experiments in proton decay.

Finally, once string theory does make real predictions, they will be hard to test. In particular, they are likely to require enormous amounts of energy, and accelerator experiments can take years to run and analyze. So it will be a long time yet before string theory becomes scientific.

Re:Neither Proved Nor Disproved

[LihTox]

I agree that if string theory isn't testable, then it isn't science (yet). However, it IS mathematics (which often isn't science either, often dealing with strange systems which have no basis in reality), and as mathematics it is certainly a worthwhile field of study. (There are a lot of physicists out there who are basically doing mathematics.)

And of course, eventually someone might come up with a way to test the string theories, and then they'll definitely be science. :)

Re:Not a scientific theory.

[jfengel]

There's a difference between what's not practically testable and what's truly unfalsifiable. As long as it's conceptually possible to come up with a falsifying experiment, even if it's wildly impractical, it's still a scientific theory. We may yet come up with ways to test the theory. Sometimes that's because somebody comes up with a clever new test, an ingenious new reformulation of the theory, receives unexpected results from an exsting accelerator, or builds a new particle accelerator.

What's happening here is that people are complaining that the scientific establishment has made it difficult to work in alternatives to string theory. But just because you can't get a job to disprove a theory doesn't make it unfalsifiable. There needs to be healthy debate in the scientific community about which theories to work on. Shutting valid theories down is not healthy for science, but neither are accusations that conflate "impractical" with "impossible".

Re:Well....

[Pitr]

It depends. If the times are not being observed, it's both, so it's Schrodinger. If they're being observed but you're just not sure, it's Heisenberg.

Ergo, ignorance is bliss... and not. ;)

Re:If it's not testable it isn't science.

[alexgieg]

You, sir, have no idea what Philosophy is.

Do you "prove" logic by testing it, or testing anything is to apply logic to the issue?

When something "becomes" science, that's because it never was philosophy. Philosophy is that discipline that provides you the tools with which you build science. Not the other way around.

Re:Thanks for the troll submission

[Morphine007]

it's true, it really is FUD.

String theory hasn't been replaced by newer versions, it's been updated with small modifications like "what if the basic premise is the same, but instead of a 1D string vibrating in 4 dimensions (x,y,z and t) it's vibrating in 11 dimensions, where the other dimensions are curled up within the planck length?"

There are reasons why string theory has failed to come up with any NEW predictions. For one thing, it's being constantly tweaked so that it is consistent with EXISTING experimentation. After all, why would you build a theory that you hope will become a GUT if it's not consistent with other proven theories?

The other thing is that this is a theory... the fact that it (mathematically) treats particles as being a 1D string vibrating in n-dimensions doesn't actually mean that if you could see items smaller than the planck length, that you would actually see a vibrating string!! It's a mathematical representation... the math doesn't have to represent exactly what's happening as long as it can be used to describe what is happening.

After all, modern chemistry is incredibly useful for predicting how atoms interact with eachother to form compounds... even though it's based off the idea that electrons orbit a nucleus like a tiny little planet orbitting a sun... that is precisely NOT what an electron does, but who cares, the math allows you to make determinations. It's the same with string theory.

I do not think that string theory is a con job. I do, however, think that attempting to come up with a GUT is a MUCH MUCH larger task than simply trying to explain, say, quantum behaviour, like tunneling.

They're starting with a very simple, and very elegant premise (that all particles are periodic vibrations with different frequencies corresponding to different particles) and then building from there. Hell... start with that and just try and figure out how to represent the periodic table... that alone would be mind-boggling. Now start trying to figure out what particle interaction would look like... then build up from there. The trick, is that it's possible to describe nearly everything using this theory... but it hasn't happened yet. Just because it's possible doesn't mean it'll be easy.

This, of course, probably means that it's the wrong way of going about it... but that doesn't make it a waste of time... the hardest part, I think, will be in having enough patience to see what the theory can produce outside of existing theories... unfortunately it has to be harmonized with existing theory ;-)

Re:If it's not testable it isn't science.

[Chris Pimlott]

I love it how this happens; whenever there is a discussion about whether something is or is not a theory, or isn't actually science, the Science People always piss of the Philosophy Poeple because philosophy always gets used as a dumping ground for everything that starts out with "what if..." but doesn't quality as science. "Damn it guys, we have rules too, you know. Stop sending us your trash!"