Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: melodysquare on 21/09/2010 09:04:05

Title: Is String Theory science or philosophy?
Post by: melodysquare on 21/09/2010 09:04:05
My first post on here, /bow. I'm sure this has been discussed, now to go through and open each thread to find out which after deciding what title it may apply to is hard, so if someone finds a link and just posts it as a reply id be happy with just that.

My question is obvious with its title, is string theory philosophy more so than science at this stage? What experiment can validate string theory? I know a lot of people when confronted with the idea of multiverse being just as plausible as God as an explanation (both things we could never actually "observe") will state, o but the difference with multiverse, (as in that which makes it scientific over God) is the math. But does finding equations that fit correctly into a puzzle really magnify the reality of what is there? For example a valid question for me would be, do the extra dimensions imposed only exist or were thought to exist because they fit an equation into another piece of the puzzle? I'd feel more comfortable with the ideas of strings, and extra dimensions, if they were observed (science), not worked in because of the math.

The problem this could create if I am right I think is obvious - The problem of quantum mechanics is being replaced by creating imaginary things to throw the problem in (extra dimensions, strings, etc). In so that mathematically it works out, but skips over whatever is reality.
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 21/09/2010 11:23:49
"The problem this could create if I am right I think is obvious - The problem of quantum mechanics is being replaced by creating imaginary things to throw the problem in (extra dimensions, strings, etc). In so that mathematically it works out, but skips over whatever is reality."


It is the study of quantum mechanics itself that has caused scientists to re-evaluate what reality is. Things like extra dimensions, strings and so on have been conceptualized as a way of attempting to encompass a grand unified theory of all the known forces, which theories such as Relativity do not achieve. People have to engage their imaginations in forming ideas about the way reality is because commonsense is no longer adequate to account for the deeper aspects of the universe. We have evolved as a species to deal with everyday 'big' objects in four dimensional spacetime, but the greater reality seems to insist we go beyond this model and use things like maths to try to provide an underlying foundation to account for both classical physics and quantum mechanics. It is always a mistake to rely on one's senses to describe how the universe really is.
Title: Re: Is String Theory science or philosophy?
Post by: yor_on on 21/09/2010 13:08:40
Seems a valid question to me. Against it you might state the fact that we expect all things to be able to describe and define mathematically, giving mathematics an universal approach. If mathematics can do so, does it implicate that all its solutions exist? Don't know, but the better it describes nature the closer we expect it to be to the 'real thing'. And as far as I understand string theory, how ever weird it might be for me, succeeds in this, able to describe what we already know as well as some things we only can guess on, like what's inside a black hole.

So, don't count out string theory, even though I find it hard to melt myself :)
Any 'philosophy' succeeding in accurately describing all states in the universe will get a vote from me, well possibly so :) Not that I'm saying that string theory is there yet. Because, as you say, to really validate a theory it will need to create an answer to a formerly unsolved mystery, or even better, create a new puzzle that only can be explained out of the new theory happening in the 'real world', not only on paper.
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 21/09/2010 17:26:27
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  Because, as you say, to really validate a theory it will need to create an answer to a formerly unsolved mystery, or even better, create a new puzzle that only can be explained out of the new theory happening in the 'real world', not only on paper.


Of course, but it is important to have in place ideas that, pehaps one day, will be amenable to testing. After all, this is how science got started in the first place, i.e. from philosophical questions that were speculated about and later subjected to testing. In this way science progresses. I suppose it's all an evolving process but you have to evolve slowly.
Title: Re: Is String Theory science or philosophy?
Post by: LeeE on 21/09/2010 22:31:34
I would say that String/Superstring/M-Theory is definitely science, but it is synthetic rather than analytic.
Title: Re: Is String Theory science or philosophy?
Post by: melodysquare on 22/09/2010 07:41:54
It is the study of quantum mechanics itself that has caused scientists to re-evaluate what reality is. Things like extra dimensions, strings and so on have been conceptualized as a way of attempting to encompass a grand unified theory of all the known forces, which theories such as Relativity do not achieve. People have to engage their imaginations in forming ideas about the way reality is because commonsense is no longer adequate to account for the deeper aspects of the universe. We have evolved as a species to deal with everyday 'big' objects in four dimensional spacetime, but the greater reality seems to insist we go beyond this model and use things like maths to try to provide an underlying foundation to account for both classical physics and quantum mechanics. It is always a mistake to rely on one's senses to describe how the universe really is.

Sure, you could argue what reality really is, is string theory and thus we should accept seemingly illogical things to be real because, well, they are, thus it sort of, in a way, changes the definition of everything, even common sense. I get that, but this is all believed because of what? Because its what satisfied an equation in the end? Or was it something that was actually observed?
Title: Re: Is String Theory science or philosophy?
Post by: graham.d on 22/09/2010 09:32:32

It is the study of quantum mechanics itself that has caused scientists to re-evaluate what reality is. Things like extra dimensions, strings and so on have been conceptualized as a way of attempting to encompass a grand unified theory of all the known forces, which theories such as Relativity do not achieve. People have to engage their imaginations in forming ideas about the way reality is because commonsense is no longer adequate to account for the deeper aspects of the universe. We have evolved as a species to deal with everyday 'big' objects in four dimensional spacetime, but the greater reality seems to insist we go beyond this model and use things like maths to try to provide an underlying foundation to account for both classical physics and quantum mechanics. It is always a mistake to rely on one's senses to describe how the universe really is.

I think you have stated this well, Abacus.

Melody, the objective of science is to try to see how the world (the universe) works. It seems to be the case that our brains are not equipped to deal with the visualisation of many of the underlying mechanisms (why should they be?). So we rely on more abstract ideas that fit the mathematical descriptions - string theory being one such concept. It is not very meaningful to think that there are really things like vibrating strings in any sense that we could "see" them, but it is a helpful analogy and there is correlation in the mathematics with the behaviour of vibrating strings at the macro level. The test we have to make, in all science, is whether the theories we have are able to make predictions about behaviour that we are able to observe and verify. String theories (there are a few) have been able to make such predictions and the goal is to keep testing the theories until we have one that survives. Undoubtedly the theory will be found to be wrong in some respect at some point in the future but that does not mean it has not been useful.
Title: Re: Is String Theory science or philosophy?
Post by: melodysquare on 23/09/2010 00:56:30

It is the study of quantum mechanics itself that has caused scientists to re-evaluate what reality is. Things like extra dimensions, strings and so on have been conceptualized as a way of attempting to encompass a grand unified theory of all the known forces, which theories such as Relativity do not achieve. People have to engage their imaginations in forming ideas about the way reality is because commonsense is no longer adequate to account for the deeper aspects of the universe. We have evolved as a species to deal with everyday 'big' objects in four dimensional spacetime, but the greater reality seems to insist we go beyond this model and use things like maths to try to provide an underlying foundation to account for both classical physics and quantum mechanics. It is always a mistake to rely on one's senses to describe how the universe really is.

I think you have stated this well, Abacus.

Melody, the objective of science is to try to see how the world (the universe) works. It seems to be the case that our brains are not equipped to deal with the visualisation of many of the underlying mechanisms (why should they be?). So we rely on more abstract ideas that fit the mathematical descriptions - string theory being one such concept. It is not very meaningful to think that there are really things like vibrating strings in any sense that we could "see" them, but it is a helpful analogy and there is correlation in the mathematics with the behaviour of vibrating strings at the macro level. The test we have to make, in all science, is whether the theories we have are able to make predictions about behaviour that we are able to observe and verify. String theories (there are a few) have been able to make such predictions and the goal is to keep testing the theories until we have one that survives. Undoubtedly the theory will be found to be wrong in some respect at some point in the future but that does not mean it has not been useful.


Do you have a reference to any of these predictions?
Title: Re: Is String Theory science or philosophy?
Post by: Geezer on 23/09/2010 06:21:16
Do you have a reference to any of these predictions?

I suspect String Theory is more at the stage of trying to tie things together than making exciting new predictions. I think that's appropriate.
Title: Re: Is String Theory science or philosophy?
Post by: graham.d on 23/09/2010 12:42:00
Do you have a reference to any of these predictions?

I suspect String Theory is more at the stage of trying to tie things together than making exciting new predictions. I think that's appropriate.

 [:)] [:)]

I think this is actually about right. It's not really my field, but I think the various string theories are able to be consistant with existing knowledge but have yet to be able to differentially tested with any experiment that is within the capability to be carried out. There are other theories that can rival string theories too. My point is really that it does not matter too much whether these theories actually represent reality as long as the maths works out and they can enable some sort of aid to understanding the maths in a form the brain can cope with. Another theory in a similar class is Garrett Lisi's predictions of fundamental particles based on the E8 lie group. I don't think that anyone is saying that this gives any physical view of the sub-nuclear world but it does allow a pattern to be produced (allbeit a complicated multidimensional one) which seems to correspond to fundamental particle existence and their behaviour. I think it maybe analogous to how the periodic table evolved in chemistry - it was many years before anyone understood why there was such a pattern of behaviour but this did not stop it being useful. Basically any theory which gives insight to the mathematics helps.
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 23/09/2010 13:10:55
 

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Do you have a reference to any of these predictions?


The problem is these ideas are essentially mathematical in nature so you would have to have some familiarity with advanced maths to understand them. The analogies given in language are to make the ideas involved easier to visualize. However, you could take a look at the following link, which serves as an introduction to M-theory and strings, etc.: http://en.wikipedia.org/wiki/Introduction_to_M-theory
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 23/09/2010 13:22:16
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I think you have stated this well, Abacus.


Thanks, graham.d, and I think we should make it clear that any ideas will evolve over time to (hopefully) attain the status of a predictive theory. You have to begin somewhere, of course.
Title: Re: Is String Theory science or philosophy?
Post by: Geezer on 23/09/2010 20:14:53
I suspect String Theory is more at the stage of trying to tie things together than making exciting new predictions.

Maybe it was a subliminal thing. Believe it or not, I didn't see the funny side of my post until Yoron pointed it out to me!!
Title: Re: Is String Theory science or philosophy?
Post by: melodysquare on 24/09/2010 02:51:53
Well the reason I ask for references is that I don't see how a theory that postulates multiverses exist can have any predictions (or maybe it can but not in reference to that aspect of it). I don't see how it can be possible to prove an event happens that corresponds to the fact of quantum mechanics in another universe without having to first take on the assumption that other universes do exist in order for the event to take place aka the experiment to make sense.

On the existence of extra dimensions im also confused, where these postulated to exist because they helped/help in understanding other aspects of the universe outside of assuming string theory is true (this is the same problem i have with multiverse stated right above in a sense, taking in an assumption to prove a math)? IE could these extra dimensions stand up on their own accord vie a proof and help explain an aspect of the universe? Or must we first assume either the strings exist or the extra dimensions exist in order to justify the other one vie a math?
Title: Re: Is String Theory science or philosophy?
Post by: Geezer on 24/09/2010 03:47:19
Re. the extra dimensions, I'm no expert on String Theory, but as I understand it, the additional dimensions are necessary to construct a model that does not contradict the existing math that predicts and describes observed phenomena. If the math holds up, it would seem to confirm the existence of the other dimensions and, of course, experimental evidence should also be sought, although that might turn out to be more than a bit tricky (to put it mildly!)

It may also turn out that ST will predict some sort of anomaly that we already observe, like, for instance, the so called "dark energy". If something like that were to happen, it would certainly add an enormous amount of weight to the theory.

The notion of additional dimensions does seem a bit bizarre, but just about everything we now accept as reality seemed pretty bizarre when it was first described. I always think it's funny that we tend to think of ourselves as rather substantial objects living on a very substantial planet. If you take an atomic perspective, there's almost nothing there at all!
Title: Re: Is String Theory science or philosophy?
Post by: yor_on on 24/09/2010 09:45:21
S000 Mr Atomic?
Are we not substantial?

As i look at myself in the mirror I wish I could agree :)
More is less I say :)
Title: Re: Is String Theory science or philosophy?
Post by: Geezer on 24/09/2010 18:17:48
S000 Mr Atomic?


Rats! My cover has been blown. There won't be much point in wearing my Spandex suit now.
Title: Re: Is String Theory science or philosophy?
Post by: JP on 25/09/2010 03:55:03
Re. the extra dimensions, I'm no expert on String Theory, but as I understand it, the additional dimensions are necessary to construct a model that does not contradict the existing math that predicts and describes observed phenomena. If the math holds up, it would seem to confirm the existence of the other dimensions and, of course, experimental evidence should also be sought, although that might turn out to be more than a bit tricky (to put it mildly!)

I'm no expert either, but from what I've heard in popular science accounts, it does ok with the descriptions of current phenomena, but it doesn't do much in terms of predicting measurable results that differ from current models.  It also apparently introduces many (infinitely, I think?) possible universes, of which we live in only one.  Although I don't find that particularly objectionable (the anthropic principle helps in my opinion), some people really don't like that, and think a theory of everything should explain why our universe has the laws it does without relying on the anthropic principle.
Title: Re: Is String Theory science or philosophy?
Post by: LeeE on 25/09/2010 17:15:32
Actually, an infinite number of dimensions makes more sense than a finite number of them, for if there is only a finite number then there must be a reason why it's that particular finite number and not another finite number i.e. why do we have only three spatial dimensions instead of four or five, or any other number?

There may be an energy relationship between different numbers of dimensions though.  For example, the inverse square law whereby the strength of a field reduces with the square of the distance from its source, that we're familiar with, wouldn't work with just two spatial dimensions and the relationship would be linear instead of squared, and if you went down to just a single spatial dimension there would no reduction in strength with distance from source at all.  Conversely, with one more spatial dimension we might expect to see an inverse cubed law instead.

So while there might be no intrinsic limit to the number of possible spatial dimensions, you'd need infinite energy for them to be expressed.  Actually, this is one of those areas where you have to deal with different sizes of infinity too, for the energy required would increase exponentially with the number of dimensions; the infinite amount of energy would need to be exponentially greater than the infinite number of dimensions.
Title: Re: Is String Theory science or philosophy?
Post by: melodysquare on 25/09/2010 21:43:27
Re. the extra dimensions, I'm no expert on String Theory, but as I understand it, the additional dimensions are necessary to construct a model that does not contradict the existing math that predicts and describes observed phenomena. If the math holds up, it would seem to confirm the existence of the other dimensions and, of course, experimental evidence should also be sought, although that might turn out to be more than a bit tricky (to put it mildly!)

It may also turn out that ST will predict some sort of anomaly that we already observe, like, for instance, the so called "dark energy". If something like that were to happen, it would certainly add an enormous amount of weight to the theory.

The notion of additional dimensions does seem a bit bizarre, but just about everything we now accept as reality seemed pretty bizarre when it was first described. I always think it's funny that we tend to think of ourselves as rather substantial objects living on a very substantial planet. If you take an atomic perspective, there's almost nothing there at all!

Its not exactly that I have a problem with "Bizarre" here or not wanting to change what may seem like common sense, im fine with that, and a lot of these posts (at least first ones), seem to tell me i just need to let go of what was previously thought, and thats fine and all like i said i have no problem with that, what I am trying to do is decipher the original question or title of this thread. Lets take for granted the argument for instance, lets say somehow we know multiverse is the reality in which we live, there are an infinite number of universes out there, now, is it plausible to discover that by scientific means? Maybe I mean to ask, how does the math imply multiverse? And just how reasonable is it for us to conclude other universes exist simply because of this?
Title: Re: Is String Theory science or philosophy?
Post by: Geezer on 25/09/2010 22:06:53
Lets take for granted the argument for instance, lets say somehow we know multiverse is the reality in which we live, there are an infinite number of universes out there, now, is it plausible to discover that by scientific means?

If you mean obtain empirical proof, I've no idea how we could do that, and that does seem to be a general issue with ST, but never say never I suppose.


Quote

Maybe I mean to ask, how does the math imply multiverse? And just how reasonable is it for us to conclude other universes exist simply because of this?


I don't think we really can conclude this without some empirical evidence, but, as I said, I'm no expert  [:)]

Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 26/09/2010 13:49:11
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Maybe I mean to ask, how does the math imply multiverse? And just how reasonable is it for us to conclude other universes exist simply because of this?


Because strings are thought to 'vibrate' in multiple dimensions and it seems there could be whole chunks of vibrating strings that exist as other universes (called membranes) with their own laws, depending on how strings vibrate in their membrane. What we observe as light, gravity and mass is hypothesized to be a manifestation of the way strings in our 4 dimensional world vibrate.


The point is that the mathematical model of strings is in accordance with the known laws and observations of science and appears to provide solutions to questions that have previously eluded science, so it is a 'good fit' based on our knowledge to date, although not testable.
Title: Re: Is String Theory science or philosophy?
Post by: Farsight on 26/09/2010 18:02:25
Melody: String theory aka M-theory has been going for 40 years now. There's no evidence for any of it, and it predicts nothing. Thus it isn't actually science, it's hypothesis at best, or pseudoscience at worst. Since it explains nothing and nobody can explain it, I err towards the latter. IMHO it has more than a whiff of "emperor's new clothes" to it.

Some will be unhappy to hear me say this, but they cannot explain it, and they cannot provide any evidence or predictions. After 40 years it just won't do. We can understand everything another way. And it is coming.   
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 26/09/2010 19:01:27
Melody: String theory aka M-theory has been going for 40 years now. There's no evidence for any of it, and it predicts nothing. Thus it isn't actually science, it's hypothesis at best, or pseudoscience at worst. Since it explains nothing and nobody can explain it, I err towards the latter. IMHO it has more than a whiff of "emperor's new clothes" to it.

Some will be unhappy to hear me say this, but they cannot explain it, and they cannot provide any evidence or predictions. After 40 years it just won't do. We can understand everything another way. And it is coming.   


The latest version of string theory was proposed in the mid 90's so it is not 40 years old. It is the best 'fit' we have so far in attempting to provide a common foundation to account for all the known forces and particles and it agrees with all of the scientific observations that have been made about the universe. It is not testable it is true, but the mathematics of M-theory have been found to be very consistent in attempting to combine quantum mechanics with gravity. I don't see what more one can ask of a scientific theory that is attempting to answer the deepest mysteries of the universe. You have to start somewhere and, perhaps, one day science may be in a better position to test M-theory or perhaps its successors. Do you simply want no effort made in trying to provide a model (even a hypothetical model) of the basis of reality?   
Title: Re: Is String Theory science or philosophy?
Post by: Geezer on 26/09/2010 19:24:46
Since it explains nothing and nobody can explain it, I err towards the latter. IMHO it has more than a whiff of "emperor's new clothes" to it.
  

Didn't Einstein receive a similar reaction?
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 26/09/2010 19:51:20
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Didn't Einstein receive a similar reaction?


Exactly. Were the Greeks wrong to conceive of the 'átomos?' The idea certainly wasn't testable!


Title: Re: Is String Theory science or philosophy?
Post by: JP on 27/09/2010 05:27:21
I'm confused by what this debate is actually about. 

Is the question whether or not string theory makes testable predictions?  I don't think anyone's arguing that it currently does. 

Is the question whether or not string theory should be considered science?  That depends on how strictly you define scientific theories to require immediately testable results.  Many accepted scientific theories require a lot of effort before they make testable predictions.  Would Einstein have been working for years in philosophy, rather than science, because his general theory of relativity took a long time to complete?  If so, is there some immediate transformation from philosophy to science when the first testable prediction is made?  Does the attempt to work towards mathematically towards a testable theory count as science?  I think that you could argue this all day and not come to an answer.  The goal of string theory seems to be to eventually yield testable results and to make sure it agrees with current observations, so I would say that yes, it is a scientific field of research.  I'd probably stop short of labeling it a scientific theory, however--maybe it's a theory-in-progress.

Or is the question whether or not string theory should be attracting funding or scientific talent, since it may or may not yield practical results?  I suspect the mathematics behind the theory will turn out to be useful in other areas, even if the theory is eventually discarded, so that funding it is probably worthwhile.
Title: Re: Is String Theory science or philosophy?
Post by: melodysquare on 27/09/2010 06:08:37
Since it explains nothing and nobody can explain it, I err towards the latter. IMHO it has more than a whiff of "emperor's new clothes" to it.
  

Didn't Einstein receive a similar reaction?

And more people that were wrong on issues probably received the same reaction as well. Reactions don't tell us anything really at all.

Quote
Because strings are thought to 'vibrate' in multiple dimensions and it seems there could be whole chunks of vibrating strings that exist as other universes (called membranes) with their own laws, depending on how strings vibrate in their membrane. What we observe as light, gravity and mass is hypothesized to be a manifestation of the way strings in our 4 dimensional world vibrate.


It bothers me on a philosophical side that - what is everything is hypothesized to be the vibration of something, even if its not a "thing" in any sense we can imagine. For the mere fact that this thing must be doing another thing (vibrating) means it takes on a property of a sort, one that is allowed and defined by what? Does it not also require what it proposes to explain? Which is to say laws? Theres an infinite regress that I think scientist will someday have to accept or be driven mad by. Anyway, thats irrelevant - kind of.

So after reading this would it be correct to state multi-dimensional implies mutli-verse sort to speak? When we get down to the smallest principle of where those dimensions cluster/meet? 

Quote
Is the question whether or not string theory makes testable predictions?  I don't think anyone's arguing that it currently does. 

Well, take for example Stephen Hawking, here we have the smartest guy in the world stating a God need not start the Universe, stated almost as if a matter of fact, here we are in a science forum, and people seem to agree this theory that his premise is based on doesn't even have any empirical proof nor even sets any testable predictions. Theres a huge disconnect between the science community and the general public, now I fear theres a huge disconnect in what scientist think they're doing and what science actually is.
Title: Re: Is String Theory science or philosophy?
Post by: Geezer on 27/09/2010 07:20:21
It might be best if you try to break down your points into separate topic questions.

I think the original question was basically "Is String Theory science?" Although it is not an accepted theory, I don't think anyone has suggested it is anything other than science.
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 27/09/2010 09:44:28
Quote


It bothers me on a philosophical side that - what is everything is hypothesized to be the vibration of something, even if its not a "thing" in any sense we can imagine. For the mere fact that this thing must be doing another thing (vibrating) means it takes on a property of a sort, one that is allowed and defined by what? Does it not also require what it proposes to explain? Which is to say laws? Theres an infinite regress that I think scientist will someday have to accept or be driven mad by. Anyway, thats irrelevant - kind of.

So after reading this would it be correct to state multi-dimensional implies mutli-verse sort to speak? When we get down to the smallest principle of where those dimensions cluster/meet? 


Using natural language to try to explain what M-theory is about is not always helpful because the models string theory are based on are largely mathematical. The trouble is, it is only natural to interpret the ideas in string theory in terms of the familiar everyday world we all know, but this is misleading because nature is often non-intuitive and even bizarre so we must not get too carried away by using familiar analogies in order to get a handle on difficult concepts. Words can get in the way in attempting to produce a model of phenomena like this, which is why people use maths. For example, who could possibly imagine what a fifth dimension is like? We have simply not evolved to deal with such ideas in any direct way.
Title: Re: Is String Theory science or philosophy?
Post by: Farsight on 27/09/2010 13:13:01
Quote from: geezer
Didn't Einstein receive a similar reaction?
There were people who were sceptical, but GR received initial experimental confirmation after only 3 years in 1919. See http://arxiv.org/abs/gr-qc/0510072 for details of other experimentation.   

The latest version of string theory was proposed in the mid 90's so it is not 40 years old. It is the best 'fit' we have so far in attempting to provide a common foundation to account for all the known forces and particles and it agrees with all of the scientific observations that have been made about the universe.
I'm afraid that's a myth. Relativity is an excellent fit for gravity, QED is an excellent fit for photons and electrons, and QCD and gauge-theory in the form of the standard model is a reasonable fit for protons and other particles. M-theory "fits anything", and with the lack of predictions and supporting evidence, it isn't actually a theory.   

It is not testable it is true, but the mathematics of M-theory have been found to be very consistent in attempting to combine quantum mechanics with gravity.
That's another myth I'm afraid. Again, if you beg to differ, explain how it does this. When you find you can't, perhaps you'll appreciate what I'm driving at with the emperor's new clothes allegation.

I don't see what more one can ask of a scientific theory that is attempting to answer the deepest mysteries of the universe.
If it was a new theory, I'd cut it some slack. But it isn't, and it's been crowding out real physics. I'm not joking about this. 

You have to start somewhere and, perhaps, one day science may be in a better position to test M-theory or perhaps its successors. Do you simply want no effort made in trying to provide a model (even a hypothetical model) of the basis of reality?
Not at all. But there are models out there that do this, but you never get to hear about them because "string theory is the only game in town".

Using natural language to try to explain what M-theory is about is not always helpful because the models string theory are based on are largely mathematical.
If you can't explain it and if nobody can, we're in crystal spheres territory.

The trouble is, it is only natural to interpret the ideas in string theory in terms of the familiar everyday world we all know, but this is misleading because nature is often non-intuitive and even bizarre so we must not get too carried away by using familiar analogies in order to get a handle on difficult concepts. Words can get in the way in attempting to produce a model of phenomena like this, which is why people use maths. For example, who could possibly imagine what a fifth dimension is like? We have simply not evolved to deal with such ideas in any direct way.
This just won't wash, not any more. The future of physics is at stake. We can understanded such ideas in a direct way. Would you like a demonstration? Think of some subject that is usually considered to be mysterious and beyond current scientific understanding, and I'll explain it in a simple fashion that everybody can understand.
Title: Re: Is String Theory science or philosophy?
Post by: Farsight on 27/09/2010 13:24:00
...There's a huge disconnect between the science community and the general public, now I fear theres a huge disconnect in what scientist think they're doing and what science actually is.
It isn't like that melody. The disconnect is in the peer-review system and science communication through the media. There's a lot of good physicists out there writing excellent papers that don't get into Nature and that you don't get to hear about. Instead what you do get to hear about is M-theory, the anthropic principle, the multiverse and other such tosh. 
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 27/09/2010 13:31:54
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I'm afraid that's a myth. Relativity is an excellent fit for gravity, QED is an excellent fit for photons and electrons, and QCD and gauge-theory in the form of the standard model is a reasonable fit for protons and other particles. M-theory "fits anything", and with the lack of predictions and supporting evidence, it isn't actually a theory.

Perhaps you would like to provide some kind of evidence for this view.   

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That's another myth I'm afraid. Again, if you beg to differ, explain how it does this. When you find you can't, perhaps you'll appreciate what I'm driving at with the emperor's new clothes allegation.


I have already explained this. M-theory is in accordance with all the scientific observations so far made and it provides a 'best fit' in uniting gravity with quantum mechanics - hypothetically yes, but, nevertheless it is the best theoretical model so far produced.  

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If it was a new theory, I'd cut it some slack. But it isn't, and it's been crowding out real physics. I'm not joking about this.


'Real' physics has not provided answers to what underlies quantum mechanics and classical physics, especially gravity, so you are in error.

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Not at all. But there are models out there that do this, but you never get to hear about them because "string theory is the only game in town".

You never get to hear about them because they are no good.

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If you can't explain it and if nobody can, we're in crystal spheres territory.

How does one explain the fifth dimension? The mathematics need to be understood and not many people can understand!

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This just won't wash, not any more. The future of physics is at stake. We can understand such ideas in a direct way. Would you like a demonstration? Think of some subject that is usually considered to be mysterious and beyond current scientific understanding, and I'll explain it in a simple fashion that everybody can understand.

Ok, explain what the fifth dimension is.
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 27/09/2010 13:38:59
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There's a huge disconnect between the science community and the general public, now I fear therIt isn't like that melody. The disconnect is in the peer-review system and science communication through the media. There's a lot of good physicists out there writing excellent papers that don't get into Nature and that you don't get to hear about. Instead what you do get to hear about is M-theory, the anthropic principle, the multiverse and other such tosh. 


Evidence please.
Title: Re: Is String Theory science or philosophy?
Post by: Farsight on 27/09/2010 13:58:20
Quote from: abacus
Perhaps you would like to provide some kind of evidence for this view.
Have a read of this Scientific American blog, which actually mentions the word crap:

http://www.scientificamerican.com/blog/post.cfm?id=cosmic-clowning-stephen-hawkings-ne-2010-09-13   

Quote from: abacus
I have already explained this. M-theory is in accordance with all the scientific observations so far made and it provides a 'best fit' in uniting gravity with quantum mechanics - hypothetically yes, but, nevertheless it is the best theoretical model so far produced.
You've explained absolutely nothing, you've given no evidence and no predictions, you've merely repeated unsupported assertions.  

Quote from: abacus
'Real' physics has not provided answers to what underlies quantum mechanics and classical physics, especially gravity, so you are in error.
Yes it has...

Quote from: abacus
You never get to hear about them because they are no good.
...but catch 22 applies. Because string theory is the trouble with physics (http://www.thetroublewithphysics.com/). 

Quote from: abacus
How does one explain the fifth dimension? The mathematics need to be understood and not many people can understand!
What fifth dimension? There isn't one.

Quote from: abacus
Ok, explain what the fifth dimension is.
No, because there is no fifth dimension. See http://en.wikipedia.org/wiki/List_of_unsolved_problems_in_physics for some real physics issues.
Title: Re: Is String Theory science or philosophy?
Post by: imatfaal on 27/09/2010 14:30:09
Farsight - I agree with most of what you are saying; but that is a crap article from SciAm. 

The finest sentiment I know of in this area is from Robert Laughlin in A Different Universe
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'Far from a wonderful technological hope for a greater tomorrow, string theory is the tragic consequence of an obsolete belief system'
  There's also Not Even Wrong by Lee Smolin - another good read. 

The physics and the maths is beyond many, and certainly beyond me; but from a position of ignorance it does seem that the time has arrived for string-theory of some-guise "to put up or to shut up".
Title: Re: Is String Theory science or philosophy?
Post by: Farsight on 27/09/2010 16:06:12
I'll check that out imatfaal, and I totally agree with your sentiment. Note though that Lee Smolin wrote The Trouble With Physics, and it was Peter Woit who wrote Not Even Wrong, see http://www.math.columbia.edu/~woit/wordpress/.
Title: Re: Is String Theory science or philosophy?
Post by: imatfaal on 27/09/2010 16:24:21
You are right.  I am conflating two good books. 

Seeing your interest in the method of progress of science, can I ask if you have read much on the history/philosophy of science?  String theory strikes me as having strange parallels with the old notion of dogmatic paradigm; the devotees are brilliant but intransigent, and forever tweaking a dying theory rather than accepting possibility of other ideas.  If string theory does turn out to be all it is made out to be then it will have had the longest and most painful scientific adolescence; but I worry that in fact it has already passed to the stage of stubborn and inflexible senescence.   However, I do prefer our world where a group of unbelievably intelligent theorists can chase a pipe-dream for decades rather than one where tenuous and potentially futile avenues of research are stopped or not funded.
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 27/09/2010 16:27:32
Quote


The physics and the maths is beyond many, and certainly beyond me; but from a position of ignorance it does seem that the time has arrived for string-theory of some-guise "to put up or to shut up".


You appear to be labouring under the misunderstanding that our science, which has been going in an organized way for a couple of hundred years or so (if that), is in a position to make testable experiments to allow us to make theories about the deepest aspects of reality. This seems totally unrealistic and out of touch to me. The point you and some others here are missing is that ideas like M-theory are a beginning model on which to hang future ideas, perhaps due to new thinking or new knowledge. Where would science be today if people had not asked questions they had little hope of answering at the time? Science is an ongoing process.
Title: Re: Is String Theory science or philosophy?
Post by: imatfaal on 27/09/2010 17:09:45
You appear to be labouring under the misunderstanding that our science, which has been going in an organized way for a couple of hundred years or so (if that), is in a position to make testable experiments to allow us to make theories about the deepest aspects of reality.
Yes, I am labouring under that misapprehension - even the most beautifully self-consistent theory must be able to be tied to lumpen reality.  The experimental evidence for many areas of truly unbelievable and deeply profound physics is astounding.  The LHC is trying, amongst other things, to recreate the conditions of the universe just after the big bang to search for the higgs boson, quantum mechanics in all its wondrous variety is eminently testable, and gr and sr make the world go round. 

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This seems totally unrealistic and out of touch to me. The point you and some others here are missing is that ideas like M-theory are a beginning model on which to hang future ideas, perhaps due to new thinking or new knowledge.

And the point you are missing is why should M-theory rather than any other be a starting point for new ideas? Few ideas have had more intellectual weight thrown at them for decades, and yet it is becoming more complex and rarefied rather than concrete and applicable.

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Where would science be today if people had not asked questions they had little hope of answering at the time? Science is an ongoing process.

Science would be exactly where it is now - because that is, to an extent, how we did behave.  However, String theory is a question that has been asked - almost ad infinitum - and is yet to yield greater physical understanding.  The mathematics is awesome, the complexity breath-taking, but the results...



Title: Re: Is String Theory science or philosophy?
Post by: Geezer on 27/09/2010 17:22:39
Ladies and Gentlemen,

We seem to be on a tangential trajectory regarding the merits or otherwise of String Theory. I'm sure there are many interesting points being made, but that's well beyond the scope of the original question. Not only that, but those points are going to get lost, and it's unlikely that anyone tuning in on this thread will learn much at all.

Soooo, we are going to insist you stick to the original question. If the thread keeps getting lost in the delta, we'll have to split or lock this topic.

If you do want to initiate a discussions about the finer points of String Theory, please frame an appropriate question and post it as a new topic.

Thanking you in advance for your cooperation!



Title: Re: Is String Theory science or philosophy?
Post by: yor_on on 27/09/2010 17:35:02
I'm confused by what this debate is actually about. 

Is the question whether or not string theory makes testable predictions?  I don't think anyone's arguing that it currently does. 

Is the question whether or not string theory should be considered science?  That depends on how strictly you define scientific theories to require immediately testable results.  Many accepted scientific theories require a lot of effort before they make testable predictions.  Would Einstein have been working for years in philosophy, rather than science, because his general theory of relativity took a long time to complete?  If so, is there some immediate transformation from philosophy to science when the first testable prediction is made?  Does the attempt to work towards mathematically towards a testable theory count as science?  I think that you could argue this all day and not come to an answer.  The goal of string theory seems to be to eventually yield testable results and to make sure it agrees with current observations, so I would say that yes, it is a scientific field of research.  I'd probably stop short of labeling it a scientific theory, however--maybe it's a theory-in-progress.

Or is the question whether or not string theory should be attracting funding or scientific talent, since it may or may not yield practical results?  I suspect the mathematics behind the theory will turn out to be useful in other areas, even if the theory is eventually discarded, so that funding it is probably worthwhile.

You are perfectly correct JP.
Einstein took philosophy extremely seriously as I've understood it. He went a far way to philosophically anchor his ideas before verifying them mathematically. Not that I understand string theory, it seems to be one of the most esoteric mathematics there is today. But even if it was proved to be all wrong for this universe we have no guarantee that it will be wrong for some other. That is, if mathematics is the language of the Gods. Because that is the unsaid truth mathematics seems to rest on, that everything can, and will, be expressed correctly if you just find the correct mathematical concepts and equations. I have great hope for our mathematics to become even weirder before we get to the truth :)
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 27/09/2010 17:39:17
The original question was: "What experiment can validate string theory?"

I was under the impression this was what was being discussed.
Title: Re: Is String Theory science or philosophy?
Post by: abacus9900 on 27/09/2010 17:51:25
Quote
Yes, I am labouring under that misapprehension - even the most beautifully self-consistent theory must be able to be tied to lumpen reality.  The experimental evidence for many areas of truly unbelievable and deeply profound physics is astounding.  The LHC is trying, amongst other things, to recreate the conditions of the universe just after the big bang to search for the higgs boson, quantum mechanics in all its wondrous variety is eminently testable, and gr and sr make the world go round. 

The LHC may or may not support M-theory. Again, you are missing the point.


Quote
And the point you are missing is why should M-theory rather than any other be a starting point for new ideas? Few ideas have had more intellectual weight thrown at them for decades, and yet it is becoming more complex and rarefied rather than concrete and applicable.

Once again, because it is the 'best fit' to date.


Quote
Science would be exactly where it is now - because that is, to an extent, how we did behave.  However, String theory is a question that has been asked - almost ad infinitum - and is yet to yield greater physical understanding.  The mathematics is awesome, the complexity breath-taking, but the results...

...will have to wait for future generations to grapple with. One often has to be patient in science
Title: Re: Is String Theory science or philosophy?
Post by: Geezer on 27/09/2010 18:10:23
The original question was: "What experiment can validate string theory?"

I was under the impression this was what was being discussed.

That's the problem. There were multiple questions. If we don't know what the question was, it's unlikely the debate will be fruitful.

I will start a topic on validation and we can debate that question there.

EDIT: I have also modified the topic title to be a bit more specific. Please try to avoid turning this thread into  a general discussion about any aspects of String Theory. We would prefer not to lock this thread, but if it becomes impossible to moderate, we will have no choice.

If you think additional topics are appropriate, please start them.
Title: Is String Theory science or philosophy?
Post by: abacus9900 on 27/09/2010 21:31:33
So much for a free exchange of views.
Title: Is String Theory science or philosophy?
Post by: abacus9900 on 27/09/2010 21:33:08
Quote

That's the problem. There were multiple questions. If we don't know what the question was, it's unlikely the debate will be fruitful.


I'm sorry, but most questions raise many more; that is the nature of debate.
Title: Is String Theory science or philosophy?
Post by: Geezer on 27/09/2010 22:24:33
Quote

That's the problem. There were multiple questions. If we don't know what the question was, it's unlikely the debate will be fruitful.


I'm sorry, but most questions raise many more; that is the nature of debate.

Quite so, but I was referring to the original post. The object of this forum is to try to answer specific questions. I'm sorry if that is a problem for you.

If you have recommendations on how we can improve the site, rather than posting them in-line, please post them in the Feedback section, or send me, or another moderator a PM.

Thanks!
Title: Is String Theory science or philosophy?
Post by: melodysquare on 29/09/2010 10:10:55
Ladies and Gentlemen,

We seem to be on a tangential trajectory regarding the merits or otherwise of String Theory. I'm sure there are many interesting points being made, but that's well beyond the scope of the original question. Not only that, but those points are going to get lost, and it's unlikely that anyone tuning in on this thread will learn much at all.

Soooo, we are going to insist you stick to the original question. If the thread keeps getting lost in the delta, we'll have to split or lock this topic.

If you do want to initiate a discussions about the finer points of String Theory, please frame an appropriate question and post it as a new topic.

Thanking you in advance for your cooperation!





I think their discussion on the merits of string theory applies directly to the question of "is string theory science or philosophy?". In a sense I am discovering that answer, and now I got a new book to read thanks to this thread, "The Trouble with Physics". On the flipside, I own the elegant universe, so the balance is fair.
Title: Is String Theory science or philosophy?
Post by: melodysquare on 29/09/2010 10:53:49
The original question was: "What experiment can validate string theory?"

I was under the impression this was what was being discussed.

That's the problem. There were multiple questions. If we don't know what the question was, it's unlikely the debate will be fruitful.

I will start a topic on validation and we can debate that question there.

EDIT: I have also modified the topic title to be a bit more specific. Please try to avoid turning this thread into  a general discussion about any aspects of String Theory. We would prefer not to lock this thread, but if it becomes impossible to moderate, we will have no choice.

If you think additional topics are appropriate, please start them.

Did you? I can't find it. If you want this thread to die that fine, i just want to see this discussed further no matter where.
Title: Is String Theory science or philosophy?
Post by: Geezer on 29/09/2010 16:10:09
Sure did. It's right here.

http://www.thenakedscientists.com/forum/index.php?topic=34188.0

BTW - We certainly do not want this thread to die. We just want to be able to answer a question, so any supporting information that helps to answer the question is quite appropriate.

The idea behind one question per topic is that it helps to focus the discussion so that the topic does not turn into a broad general discussion with no particular conclusions. It also helps prevent misunderstandings. It's quite easy for two posters to be in violent agreement because they are trying to answer two different questions  [;D]
Title: Is String Theory science or philosophy?
Post by: yor_on on 29/09/2010 16:51:14
I think string theory is doing what it can to model our universe. But the math becomes so extremely complicated and esoteric that people like me get a headache after just reading a couple of sentences. And I'm talking about the math now.

" In the late 70s and very early 80s bosonic string theory had been constructed, initially with the hope it might explain the interaction between quarks. This was because the force between two quarks seemed to act like a string or tube between them, if you pulled them further apart the force attracting them increased, as if connected by a bit of elastic string.

Eventually QCD won out, using the notion of colour confinement and gluons to construct 'flux tubes'. String theory then entered a bit of a lull because bosonic string theory had problems with tachyons, as well as being totally unphysical because it lacked fermions. Someone then realised that if you put in fermions, a number of amazing things happened. The tachyons disappeared and the theory was supersymmetric. Previously, supersymmetry (which had been developed for usual QFT around the same time as bosonic string theory) had to be tagged on by hand, you could have unequal numbers of fermions and bosons. In string theory, if you had both kinds of particles, you had to have equal numbers!

However, there are varying degrees of supersymmetry. N=0 means 'no supersymmetry'. N=1 means 'a little bit' (in very non-technical terms) and it goes all the way up to N=8, "that's ****loads of supersymmetry!". The bigger the value of N, the more extra particles there were predicted, as if the particles we can currently see are a smaller and smaller tip of an iceberg. N=0, we can see all the iceberg, N=1 we see about half of it, N=8 we only see the very edge of it. The value of N also alters the particle content. N>1 is excluded by experiments because it doesn't account for the left/right handed nature of the Weak force (known as 'chirality'). Usual constructions of superstring theory had N=2. A bit of a problem.

Another problem was that superstring theory had lots of dimensions, 10 of them (9 space, 1 time). But we only see 4 (3+1) so the only way that makes sense is if 6 of them are too small for us to see with experiments. In QFT (and relativity in general), energy and length are inversely proportional (if you set c=G=1, your units are such that units of mass = 1/(units of length)), so that in order to access smaller and smaller length interactions, you need more and more energy. This makes sense if you think about how we need bigger and bigger accelerators to probe smaller and smaller objects. So if these dimensions hadn't appeared yet, they must be very small. Experiments say smaller than 10^(-15) metres, theory says as small as 10^(-35) metres! We'd need an accelerator larger than the universe to get that kind of energy!

So how to get past these two problems? Well one problem fixes the other. We have to make 6 of the dimensions small, 'compactified'. But how we do that affects the symmetry of our theory and so alters the amount of supersymmetry. If you compactify your 6 extra dimensions in the simplest way, onto 6 circles (ie a 6d torus, T^6), then you quadruple the amount of supersymmetry your theory has. So a 10d string theory with N=2 goes to a 4+6d string theory with N=8. Bugger, that didn't help.

Well perhaps our ideas about compactification need to be refined a little? Perhaps we need to make the small dimensions a little more complicated. This is where holonomy comes in. We want a theory with N=1 supersymmetry. This is akin to saying that we want a unique spinor in our theory under parallel transport around a closed loop in our space-time. In n dimensions, parallel transport around a closed loop acts like an operator on the spinor, specifically like a membler of a subgroup, G, of SO(n). In flat space-time G=SO(n). However, in complicated spaces you get G < SO(n). It turns out that in order to get a working theory, you need an even number of dimensions in your compact space, so n=2m, and to get the right kind of supersymmetry you need an holonomy group G = SU(m).

Through some rather unpleasant differential geometry (see Joyce), you can prove that a manifold with SU(m) holonomy is Kahler and Ricci flat and has vanishing 1st Chern Class and that's known as a Calabi-Yau space (since Calabi predicted and Yau proved those properties are equivalent). Thus 3 dimensional (3 complex dimensions) Calabi Yau spaces form the core of string theory interest in compact dimensions. Orbifolded and orientifolded tori are a kind of step in the right direction. A general Calabi Yau doesn't have anywhere near the nice description that tori do and you'd have to work through a huge number of cases. At present the orbi/orientifold constructions allow us to see the kind of problems which will arise in full Calabi Yau models and learn how to solve some of them in a nicer environment.

The difference between an orbifold and an orientifold is that an orientifold has had an extra quotienting process applied to it. Rather than just an orbifold group G, an orientifold also have the group (-1)^(F_L)Os quotiented out. (-1)^(F_L) is the 'left fermionic oscillation counter'. It's +1 if there's even numbers of fermionic oscillators going 'to the left' and -1 if odd. O is the worldsheet parity operator and s is an involution (ie a Z_2 map). Sometimes orbifolding isn't enough or you want to have additional structure."

On a 'a quick history of compactification' by AlphaNumeric, who actually works in this field.

And just reading this makes me realize how easily one can lose oneself in this type of advanced mathematics. But as I said, I have great hope and faith in mathematics and I think they are on to something. Another thing I wonder on is how they see it, as a linear field of study, or as a non-linear.
Simply expressed, how do we expect non-linearity to come out of linearity?
Title: Is String Theory science or philosophy?
Post by: graham.d on 30/09/2010 16:08:25
I like the concept of being in "violent agreement", Geezer :-)
Title: Is String Theory science or philosophy?
Post by: Geezer on 02/10/2010 03:58:00
I like the concept of being in "violent agreement", Geezer :-)

I can't remember where I first heard that one, but it is a goodie.

Anyhoo, in this month's SciAm, Stephen Hawking and Leonard Mlodinov question if any single theory will ever emerge as the "Theory of Everything". They seem to be of the opinion that it's quite likely that we will have to continue using the most appropriate theory for particular situations.

If they are right, String Theory, or M-Theory, or whatever it morphs into, may turn out to be a bust.

As an aside, in the same article, they point out that Copernicus didn't prove that Ptolemy was wrong about the center of things, he just made the math a lot simpler! (I'm paraphrasing a bit, but it's a very interesting point.)
Title: Is String Theory science or philosophy?
Post by: yor_on on 02/10/2010 17:27:57
Yep, it's about Occam's razor, we use it and we hope that the universe agrees :) If it have another view on it it at least have to be 'simple' too me thinks. Maybe a 'super position' is the 'simplest thing' there is as seen from the universe's view, that and entanglements?

Why, if that is so Occam's razor still stands :)
So we get the best of two worlds, QM and Relativity.