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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.)"
This isn't some reasonably objective piece on string theory; the author appears to be skeptical from the start, and BARELY lets up. I'd hoped I'd be reading a critically analytical article but I guess not. Wake me when the "story" is such.
Blacker than my baby girl's stare. Black like the veil that the muslimina wear. Black like the planet that they fear...
So how is that any different from intelligent design? If you can't test it, it isn't science.
None of that means it isn't true, of course...
Dude, I think I can see my house from here.
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".
It's philosophy.
String theory is at the moment, philosophy. As soon as someone comes up with a way of testing it, it will become science.
Deleted
Let the physicists, who are the only people who can truly understand this, sort it out. They likely don't need the academic process becoming any more politicized than it already it. If it's a blind alley, they'll find that out in due time. While it's regrettable that it's taking as long as it is to reach a conclusion on the issue, come on - it ain't exactly flippin' burgers, and we're not exactly hung up waiting for the result. Let the scientists work.
there is no need to sign your posts. this isn't usenet. your username is right there above your post. stop it.
Scientific theories are not proved. Good theories are just never disproven. We don't have a proof on why the Law of Thermodynamics must hold true. It is just that no one has ever observed this law being violated. I recall you can restate 2nd Law of Thermodynamics as entropy always increases. Well, let's assume the Big Crunch happens. If universe is getting smaller, then it'd have to be the case the entropy spontaneously decreases (everything is getting crunched together and thus more orderly). Voila, the 2nd Law of Thermodynamics can be violated if the universe doesn't expand forever (which we're not sure until only very recently). Again, it is a Law because it has never been observed to be violated. It is not an inherently true property of the universe under any circumstance.
Further, a theory has to be disprovable to be a theory. We have the theory of gravity and we believe it works because if it doesn't work like what we claim, we would observe a lot of contradictions from just about everything. The Laws of Therodynamics can be disproved, and we believe the law works because it's never been disproved despite plenty of ways to do it. Something that cannot be disproved at all is not a scientific theory. It is only a hypothesis.
String theory is at times one of the biggest con jobs in Physics, and at other times some of the most interesting speculation. It's also the 'Theory that will NOT die!' reminding me of so many late night C rate thrillers.
Why? Because everytime string theory gets disproven, they come out with a new theory and call it 'String Theory'. String Theory from the 70's really doesn't resemble current string theory much other than the name. It's strange that this is so, but there are a lot more politics involved than there is science at times. And the author is right, there are lots of articles being written, but not much going on that can be said to prove the theory, and little in the way of predictions (cause those could be tested). And so far, everytime someone does stand up and make predictions, it quickly gets disproven by actual tests. Which may be why no one is predicting much using it anymore.
At this point actually String Theory may very well be the most 'disproven' theory in physics. But that doesn't seem to stop people from trying. It will be curious to see what science has to say about all of this 50 years from now. To be honest I think many of us have gotten too close to the subject to be objective about it, and I think that is not helping the issue on either side.
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.
Blasphemy is a human right. Blasphemophobia kills.
String theory might not have earned the rights to be called a theory yet, but as with Bohr's model of the atom, perhaps we could agree that it has earned the right to be called a model.
Ben Hocking
Need a professional organizer?
Seriously, the case may be that the reality of the Universe is so complicated that String Theory will take a long time to come to fruition. Also, it may be that there are no testable predictions because of our limited perspective.. eg 3 dimensions.. limited energy resources.. Fundamentally limited abilities to measure..
Or maybe the Universe is just a big knot of strings, and no human can untie it.
I am fud.
A Good Troll is better than a Bad Human.
In the context of science, "theory" does not mean "unproven." It is very far from "guess." We have "the theory of gravity" and "the theory of evolution." When someone says "evolution is *just* a theory," remind them that gravity is just a theory too, but that seems to be working out okay.
I don't think that there is a theory of gravity. We know gravity exists. We can quantify it. We have a law of gravity based on those observations. But laws are not theories. A theory of gravity would explain how gravity works. So far we have only hypothetical gravitons. When these and gravity waves are someday detected and quantified, then we may have a theory of gravity.
If Slashdot were chemistry it would look like this:Cadaverine
While some of the math might be right, the same theory applies to friggin role playing games, too. So, are those real just because their math ads up?
Where are the good string theory experiments? Nowhere.
I scream. You scream. I assume that means we're both acquainted with the problem. We proceed.
Mr. Glashow can be a genious in the field of Physics, but I doubt he's also so much of a genious in the fields of History, Philosophy and (yes) Theology to be able to make such an absurd statement. No matter how much he dislikes religion and related subjects, there's a difference between stating a personal taste and talking meaningfully about something you don't know about.
Conservatism: (n.) love of the existing evils. Liberalism: (n.) desire to substitute new evils for the existing ones.
I don't think it's smearing science, indeed in some ways it's keeping intact science's integrity in the face of "ID" and other anti-science movements.
String theory appears, for the most part, to be a very smart, very compelling, system that could be used to explain how the universe works. As such, it's easy to get lost in the excitement and forget that the current evidence for it is, well, not what it could be.
The author is saying "We should hold off and be careful about how we portray this, especially in relation to other scientific principles like relativity. It clearly isn't in the same class." That's absolutely right to do, and it helps prop up the scientific method if there's this kind of auditing going on all the time. It's no more defaming science than it is for someone to come up with a new "test" for relativity, who then does that.
You are not alone. This is not normal. None of this is normal.
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 ;-)
Oh god, that woman is John Romero!
String theory doesn't make testable predictions. Therefore it is not a theory: "A theory in technical use is a more or less verified or established explanation accounting for known facts or phenomena" It is in fact only a hypothesis.
This doesn't make it not science; it's just not a theory, and calling it a theory, no matter how sure you are it is right, is not science either.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
This is exactly what I felt about quantum mechanics as well. Compared to Einstein's relativity, it was too complicated, too random, to messy. That's why when I first heard of string theory I was interested. Just one component a string. But then they said it has 10, or 11, or 33 or however many dimensions they have nowadays. And the math was showing values what were just so hugely large or small that nothing could be tested.
Personally I think both quantum and string theory are like those old models that showed the universe going around the earth. And as more accurate observations of the heavens came along, the modelers would add wheels inside of wheels inside of wheels to compensate for the observed movements. I'm hoping to live long enough to see someone come along, put a few lines on the blackboard that turn one of our assumptions on its head, that explain all the effects, and watch a stunned audience go silent and then say "of course, why didn't I think of that?".
Insolubility of the quintic, Godels Incompleteness Theorem ..... Sure it's possible to prove something can't be done. Maybe Scott Adams isn't the best source to base your view of logic.
"A theory of gravity would explain how gravity works."
... and I don't know of any "explanation" of Einstein's equations except "it's pretty mathematics, and it works."
We do have such a theory - general relativity reduces gravity to
geometry - and some additional (testable) theories about the geometry of spacetime.
It's very pretty: There is no such thing as "gravitational force." Freely falling objects follow geodesics, which are the paths of "extremal proper time" between events. This simple formulation wasn't possible until physicists accepted the possibility that spacetime is curved, and learned the mathematics of differential geometry.
I left out some really difficult stuff about how the distribution of momentum determines curvature
You might argue that this explanation of gravity is more complicated than the problem it was supposed to solve, but General Relativity predicted things that were later observed.
Don't mess with The Phone Company. Piss them off and you'll be using two tin cans and a piece of string.
Maybe after this period, people can be less childlike and some serious discussions about its strengths and weaknesses can begin.
String Theory proves Intelligent Design!
The common result of String Theory models is a totally untestable prediction - that there are an infinite number of 'parellel' universes besides our own.* The only to avoid this prediction is to claim that the fundamental constants are all non-randomly selected **. ID makes only one untestable prediction, one God (OK, so some advanced forms of ID predict a few thousand gods with various numbers of arms and three aspects of an Uber-God at the top, or one God, his kid, a ghost, and X number of angels of seven different types assisting, but even these elaborations make a finite number of predictions). Applying Occam's Razor, any finite number of untestable predictions is greatly to be preferred over an infinite number of untestable predictions, and applying My Razor, we should throw out the theory that makes an infinite number of untestable predictions first, way before we reject any of the others (Artifakt's Razor - nothing makes a situation more absurd, more quickly than dragging unnecessary infinites into it). Now we just have to test all the deistic religions and see which one is the simplest theory that encompasses all observations. This should be very simple. Of course we should leave the door open for new models, just ones that don't veer towards such unnecessary complexities as infinities imply. Still, I'm confident that once we are not wasting time on the totally untestable, we should be able to settle the remaining questions in a few years, without the delays and even the potential for bloodshead*** that infinite models impose.
* Some String theory models require an infinite number of parallels formed at the same time as our own, a very, very big finite number of ever branching quantum divergences, an either very big or infinite number of scale repetitions of the observable part in the greater universe, and possibly a fourth either very, very big or infinite number of universes formed at different times than our own. A few predict an unobservable multi-cosmic evolutionary trend or two as well.
More seriously, "unobservable" is the cosmologists own choice of words there - If you are one of those people who holds string theory is science because not immediately observable does not equal not observable, the actual practitioners of String Theory are the ones saying Nope, Nada, Never! (In other words, ST scientists aren't trying, in that they are, at least in part, making what they themselves claim are forever untestable predictions. This hasn't stopped a few of them from seeking more funding to not prove the unprovable).
I'm only half being facetious there - there are some real con games going on in this field, by people only one step removed from the "Infinite free energy from the Zero Point" crowd of patent scammers.
** Anyone wishing to is certainly allowed to propose non-deistic entities that can non-randomly select the fundamental physical constants, if they so desire. It sounds like "midget NBA player" to me, but at least it's not infinite and untestable.
*** Rumors have come to my attention that proponents of rival theorys have apparently stooped to such unscientific methods of testing as fisticuffs and possibly worse - All I can say is what do you expect when people propose such poppycock as infinite unobservable parellel universes in an effort to muddy the watters of Cosmology.
Who is John Cabal?
"Sterile" neutrinos, Supersymmetric particles, Kaluza-Klein particles, Energy 'leaking' into higher dimensions...
These are some of the predictions of string theories.
And they all can, to some degree, be tested empirically.
All the technology that needs to be implemented to do this isn't readily available right now, but hopefully, in coming years with experiments such as LHC and IceCube coming online, we could start to see meaningful results - Remember, it took years for empirical confirmation of General Relativity, simply due to technical limitations.
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.
Yes, and physics is full of mathematically complex theories (like schrodingers wave equations for example) but you can still predict where an artillery shell is going to land based on Newton's theories.... the theory you use is determined, in large part, by the domain you're trying to find a solution in. You wouldn't, for example, try to use QM to model the collisions of balls on a pool table. Likewise, you wouldn't use QM to try and model gravitational interactions between bodies... but the intent of string theory is that you'd be able to do either using the same framework... that alone should give some insight into the complexity of the theoretical underpinnings of it.... and explain why "breakthroughs" are taking so goddamned long. It has to maintain consistency in domains where other theories can't even represent what's going on... let alone provide the mechanism for making predictions in these domains.
Oh god, that woman is John Romero!
No one is saying that st isn't testable, just that it would be wildly impractical to test it. Just suppose that we become a type 3 civilization in the kardashev scale. Then we would count with the energy needed to prove or disprove the string theory (even if an advance in string theory itself that would provide a better way to verify it doesn't occur). So if we are saying that in the current theoretical state, given the resources, we could contrast st, then it is science. The fact that we don't have such resources doesn't means that it isn't science, just that it is a hypothesis instead of a theory. btw, math IS a science, allways
What I do not understand about all the negative comments on string theory is that they seem to object to it purely on the grounds that it has not yet produced a testable prediction. If there was evidence out there that it will NEVER produce a testable prediction then I would completely agree with the critics. To my knowledge this is not the case. There are certainly incredible problems to extracting a testable prediction but does that mean we should give up, pack up our bags and go home?
Sorry but sometimes physics is hard - even for physicists! Of course it might turn out in the end to be a waste of time from the physics point of view (although I'm sure even then it will leave a legacy of interesting maths) but we don't know that yet. Giving up on, from my understanding, the most promising avenue of research just because it turns out to be hard to figure it out is not good physics.
Sure they are testing it. They're testing it with mathematical hypotheticals on a chalkboard. Thats all they can do at this point. Until such time we *think up* a way to physically test what we are churning out with string theory mathematics, it will only progress by more chalkboard hypotheticals.
As far as differing from Intelligent Design? Does that particular religious belief propogate from mathematics, its systems, relativity(?), and the conundrums of space, time, and energy?
Is there a particular way you test for Intelligent Design? Oh thats right. You don't test religion. You follow its beliefs...
Mod parent post down for comparing microscopic dust to a Unicorn.
This reminds me of Evolution, in the sense that the label "Evolution" is applied to all areas of science: Biology, Astronomy, Geology... It's as if no one would ever refute anything called "Evolution" for fear of being labeled a religious fundamentalist.
I'm uncomfortable with the automatic acceptance (at the popular level, anyway) of anything labelled evolution, without proper scientific examination. I see this all the time on documentaries, TV shows, talk shows. Some scientist will say "Oh, that's evolution." and the host will just nod his head as if it were the most obvious thing in the world.
Maybe it's just me, but if we want to keep religion out of science, we need to start with ourselves.
O.R. is not science. That's why it's not called "Occam's Law". It's about as useful as an analogy in a discussion, and about as scientific.
Just because something is easier to understand, doesn't make it true.
A year ago, nobody would force this nonsense to the table.
I can't stand popular memes! Occam started making the rounds after Jodi Foster popularized him in Contact. Ugh. The number of dumb and dumber arguments resulting from a little mis-applied knowledge was astronomical. Bubbo's Ridiculous Law, (Or whatever his name is) which states that the well-accessorized geek must close his ears upon hearing the word, "Nazi" is another.
While not quite as destructive to a healthy mental process, this cross-culture, (geek culture, that is) sudden need to lecture other geeks left and right upon the proper use of the word, "Theory", is just as annoying.
You watch. It will be mis-applied by geeks trying to knock the wind out of interesting, new ideas by declaring the ideas to be beneath even the rank of theory and therefore somehow worthy of contempt. I've seen so many people who are scared to think for themselves that unless all the ideas in their heads have been validated by somebody else, (TV or other annoying geeks with name tags), then they will shie away from them at all cost.
It's the old jr. high programming. If you are different, you will be punished through ostricization.
A cowardly geek is useless.
-FL
Yep; there are so many free parameters to superstring theory that it seems that it would be possible to create a version to suit almost any experimental observations. I know that the hope is that one day some version or other will make a useful, experimentally verifiable prediction (after all, these people are not remotely stupid; they do realise that a theory is required to make predictions), but one cannot help suspecting that, when that day comes and if the prediction turns out to be wrong, they'll just tweak one or more of the free parameters to create another one of the infinite number of possible theories so that the nre version does match the experimental result (and which will presumably make some sort of prediction for a future experiment). Wash; rinse; repeat.
I can understand why string theorists get excited about their work: there is a certain elegance to it all. But I cannot be sanguine that it will turn out to be a ToE. It may or may not be a ToN(othing); one suspects that at least some useful things will come out of it. But one cannot help thinking that it will be some much, much simpler revolution and new of looking at things that provides the real breakthrough.
Some of these are valid complaints, some are not. Responses from a one-time string theorist:
1. Yes. It's a shame. The usual response is "Well how's _your_ quantum gravity theory coming," which tends to shut people up. But there are other interesting responses. See Lenny Susskind's recent book.
2. That's the wrong way of looking at it. While we thought the cosmological constant was zero, no one really looked to see if you could get nonzero ones in string theory, since you could clearly do zero. Once we saw that it wasn't zero in nature, people started looking in string theory, and realized that you could do it pretty easily, and in fact, it is probably more general for the cosmological constant to me nonzero in string theory.
3. It's not that string theory is invalid in time-dependent spacetimes, it's just that we don't yet understand how to calculate much there. We have some ideas. It is true that most of our understanding of string theory is background-dependent--that is you have to specify a spacetime background before calculating anything.
4. This is true. This is a very difficult problem, and is really a job for the mathematicians. Even quantum field theory, a very well regarded theory, has some mathematical problems. Because we can't prove things, what we do is calculate them in different ways. So far, almost all of these calculations don't disagree with each other (there is a little debate about one or two).
5. I wouldn't characterize these arguments as strong. And string theory does not really assume that spacetime is continuous, though it's a little hard to explain why. Briefly, spacetime is an emergent phenomenon of the theory, and words like "continuous" or "discrete" don't necessarily apply. It is certainly true that string theory is blind to variations in spacetime on very small scales, which is very similar to a theory with a discrete spacetime.
Two final comments: The article, and many people, blame string theorists for this problem, which may be fair. But the real reason for it is that physicists have no interesting, fundamental experimental puzzles, and haven't for more than twenty years. So they don't have anything better to do than try to work out this fascinating theory. This may be changing a little, as interesting cosmological data emerges, and may change dramatically with the LHC.
Also, complaints about testability were levied not too many years ago against another theory: cosmological inflation. Now we have new ideas of how to test it, and we're doing so. So far, it's passing with flying colors.
But it's a valid thing for people to talk about these issues, and I think most string theorists welcome the discussion.
Don't try to explain it with 4 or 5 dimensions, because that's far too challenging to imagine, much less to use as a base of an analogy.
Compare it to a cube. People know what cubes are. Say that you're trying to measure a cube, so you take the measurements of every edge of the cube, 12 measurements in all. Then you realize that really there are 3 sets of measurements, containing 4 identical measurements along the height, width, and depth of the cube. Suddenly something that seemed like a 12 dimension object really only seems to have 3 dimensions now. That's roughly how String theory "loses" dimensions over time. The first time I heard of the theory, it needed over a hundred dimensions to work, then around 80, 60, etc. Now I'm wondering if it's under the 12 that my memory told me it either hit, or might hit.
Finally, you could notice that you don't really have 3 measurements, you have one set of three identical measurements (because it's a cube the height, width, and length are all identical) So you only really have one dimension now. Of course, you dimension only applies to the "cube" universe, where everything must be a cube. However, that's the danger of models, they can become disconnected from the constraints of the real world they are modeling.
A perfect example of such a disconnect is the idea of a circular orbit around a moving planet. All planets move, and it's impossible to maintain a stationary circular orbit because the planet will move closer to one side of the circle, increasing the gravitational pull on that side, twisiting the circle into an elliptical shape.
What a silly thing to say! String theory is scientific no matter how they arrive at their results? What if they're using a Ouija Board?
Anyway I think you misunderstood me. I don't disapprove of their methods. I am not saying you can't rely on assumptions and empirical results to form your theory. That's how all scientific theories get formed. But that methodology does automatically mean the resulting theory is scientific, or that the result is a better scientific theory.
I can go out and do an experimental observation of grass, and then formulate the theory "grass is green". This makes a prediction. It is falsifiable. But it is not a scientific theory, because it explains no more than what I'd already observed. I assume you agree to that much? You need to predict more than you assume. Part of the critisism here is based on the fear (voiced also by 't Hooft) that string theory may ultimately amount to little more than that.
It's true that you can argue it's still a scientific theory since it does explain more than it assumes, in the same way QM and relativity does. But if it makes the same number of assumptions, then it's not a better theory than those two. It's not even a new theory. It's just a useless restatement of the old one.
To give such an example: Does the Earth orbit the Sun? The heliocentric model doesn't assume more than the geocentric model. One doesn't explain more than the other. The heliocentric model is just simpler, and therefore more useful.
As I understand it, you're saying it's fine to sacrifice the goal of fewer assumptions for the goal of a more general theory in this case. That's not a view representative of what most physicists think. I'd say the goal of fewer assumptions is actually much more important in this case.
QM and relativity already explain everything we can observe so far. Likewise, what we know them not to explain (e.g. singularities in relativity) is not observable. Science is not in the business of explaining the unobservable in terms of the unknowable, and any such theory is simply unscientific, no matter how rigorous it is in terms of logic.
(Don't get me wrong, any GUT, even such an unscientific one, is still a great intellectual achievement. Just because it's not scientific knowledge doesn't mean it's not knowledge. Math is not a science, as far as I'm concerned. It's still knowledge. Logic is knowledge. Even metaphysics is knowledge - albeit not a very useful kind.)
However: It's entirely wrong to make any kind of blanket statement that string theory is unscientific. I am not doing so, nor are any critics that I know of or would consider listening to. There's no point passing judgement on a theory until there's a finished theory to judge. They're currently nowhere near that point.
But the issue of scientific rigor isn't just the aforementioned philosophical problems. There's also a more obvious social problem. String theorists are largely working in isolation from the rest of (theoretical) physics, and increasingly so. That constitutes a major warning-flag in terms of scientific rigor. Isolation leads loss of critical distance and creation of group-think. Good science is almost never done in isolation.
Because of its big goal, string theory is extremely popular and well-funded. It's a prestige subject. (and many string theorists have the big heads that go with it, another warning sign) The rest of theoretical physics is not so well funded. So a lot of people think that it's getting an inordinate amount of resources, giv