I’m not aware that the math in string theory is all that much different from the math behind other theories. There have been plenty of other cases where the math makes predictions that are later tested - relativity for instance.
I wouldn’t even try to understand the math, but reading Greene makes me think that the math is a mess at the moment, unable to really predict the number of dimensions. That is not the first time, didn’t Feynman clean up a lot of infinities?
But Darwin had a lot of supporting evidence, and the theory of evolution leads to many was of falsification. So, I think it is a good example of a real theory, even though the distinction wasn’t as clear when Darwin wrote as it is today. The theory of gravity was about how gravity worked, not why it worked - and again even if you disagree that it should be called a theory (maybe more a law) it could be said to be grandfathered in. I’m not sure that modern explanations of gravity rise to the theory level either.
But hypotheses are testable also. Theories are hypotheses which have not been falsified yet, though experiments which could falsify them have been done, and for which there is at least some evidence. If the math made some very precise predictions, even if these can’t be verified yet, I’d be fine with calling String Theory a theory. My understanding though is that the math is still too messy. And you can certainly falsify a hypothesis using math alone, if the math leads you to a contradiction, and absurdity, or a prediction contrary to observations.
But maybe there’s a sense in which “We live in a possible world” is falsifiable. For if I were to observe that inconsistent statements are true, I’d thereby discover I live in an impossible world.
(It’s hard to imagine what it could possibly be like to observe inconsistent truths. But that doesn’t mean there’s nothing it would be like.)
If this is right, then the unique theory of everything may be falsifiable in the same sense–though it shows that things are as they necessarily must be, nevertheless, counterfactually (and impossibly) observations inconsistent with this theory would show it to be false.
In other words falsifiability may be substantiated by true statements about counterfactual situations situations without respect to those situations’ possibility or impossibility.
ETA: I’d never heard that argument that the unique theory of everything can’t be falsifiable–do you know of somewhere else that it’s been put forth?
> Good point Wendell, except that string theory isn’t simpler, it’s the only
> candidate that can include both quantum mechanics and relativity in a single
> consisent math framework. So a better analogy to that might be
> thermodynamics, which found a way to wed two apparently contradictory
> theories, both of which having very good evidence (heat conservation vs
> conversion between heat and work). Those don’t seem contradictory now, but
> it’s because we know about “energy”, a concept that didn’t exist before
> thermodynamics.
>
> However, like string theory, thermodynamics had testable predictions that
> contradicted both theories (or at least, were not predictable by either theory).
> The difference between then and now is that 19th century had the tools to do
> the new tests. We are just beginning to have the tools to test string theory.
> SCSC has the ability to confirm (but not deny) string theory, if one of the
> dimensions happens to be near the big end of its possible range.
Learjeff, I think the only way we differ here is in the meaning of the word “simpler.” If, in some fashion, string theory could define the proper values for the variables in it, could produce some experiments that show that it makes some correct predictions, and could tie together other parts of physics, I would say that it is simpler. Current physics has relativity and quantum mechanics, which each make useful predictions in their respective fields but which seem to be inconsistent overall. Current physics has things like dark matter, dark energy, and cosmic inflation, which seem to need arbitrary assumptions to get them to work. I believe that there are other cases where the values of variables need to be arbitrarily set. String theorists think that they can someday do this. The rest of us wait for them to show us.
Incidentally, (moving on now to other people’s posts) string theory is a theory in the same sense that relativity, evolution, and gravity are theories. The term “theory” in science does not mean “random guess with no proof.” Rather, it can apply to anything from a long established field which makes many good predictions and which fits into other scientific knowledge about the universe very well to a recent tentative hypothesis which has the possibility to explain some things but which as yet hasn’t been tested much or even fully formulated. In other words, it covers a whole range of things from very well accepted ideas to ones that have only recently been proposed. Calling string theory a theory doesn’t say much about how well it’s accepted.
No. Religion is typically internally contradictory, and it’s based on nothing but the simple assertion it’s true; scientific theories are based on real phenomena and on other scientific theories, not on some prophet somewhere just saying it’s so. And if a scientific theory is internally contradictory, that’s acknowledged as evidence that it’s flawed, not shouted down with speeches about how it’s an unfathomable mystery and you need to take it on faith. As well, there are always aspects of a religion that are dogma; unquestionable; that is the opposite of science.
Also, apparently unprovable scientific theories often have practical uses; the fact that aspects of quantum mechanics as of yet can’t be proven doesn’t keep engineers from building working electronics using the theory. And if you just dismiss such theories out of hand, you’ll never look into them deeply enough to find that they are provably right or wrong after all. That doesn’t apply to religion either, since religion is consistently wrong, and its followers simply ignore or rationalize any internal contradictions or contradictions with reality it has. Nor does religion work, unlike science; there’s no practical reason to stick with it, nor is there empirical evidence that there’s anything real to religion despite us supposedly (we do in fact understand it; it’s just that “it’s nonsense” isn’t an acceptable answer) not understanding it.
Basically, you are trying to equate a log cabin and a heap of driftwood because both can loosely be described as “a pile of wood”. One is organized and useful; the other is just a mess.
Unprovable theories or models can be helpful even if they only help us grasp something or suggest new avenues of approach.
IMHO, the best example of an unprovable theory is the multiverse explanation of the statistical aspects of quantum mechanics. That doesn’t suggest any new avenues to me, so maybe it’s not in the “useful” category. But it’s interesting to ponder.
Wasn’t Mendeleev’s original idea regarding the Periodic Table of the Elements also mathematical abstraction with only a little real observational data? It was similar to Bode’s Law regarding distances of planetary orbits: it sorta worked, mathematically, but that was all.
In time, real observations were made to support Mendeleev. Bode is spit out of luck: his “law” isn’t any such thing at all.
At this point in time, String Physics is in the same situation: it’s early. It’s speculative. It’s mathematically lovely – most exceedingly so! – but it doesn’t have any evidence to back it up. At this time, no one can even suggest a scientific test that could verify (or falsify) it. The engineering doesn’t exist.
As I said in another thread: yesterday’s nonsense can become today’s sense. Before spectrography, it was meaningless to speak of the chemical composition of stars and nebulae. Today, it’s a well-established science. Today, String Physics is in the situation of pre-spectrographic interstellar chemistry: nonsensical!
What do you mean by “declare themselves to be unprovable”? I can think of at least three cases.
1: The Many Worlds interpretation of quantum mechanics. Or, for that matter, any other interpretation of quantum mechanics. They all predict exactly the same observations, in all circumstances, so there’s no scientific basis for preferring one over another. Thinking in terms of one or another might make it a bit easier to see the simplest way to set up a problem, but any calculation that’s valid in any interpretation is valid in all of them. And, in fact, physicists mostly don’t think in terms of any of them. Note, however, that while no interpretation of quantum mechanics is testable, quantum mechanics itself is testable (and has an excellent track record for passing those tests).
2: The string model (which I will not call a theory). The string model is, at least in principle, testable, but it isn’t in practice, for two reasons. One, there are such a very large number of possible values of all of the parameters, that even if you rule out large numbers of them, there are still a huge number of possible parameters you haven’t yet ruled out. And two, most of those parameters, to even test them at all, you’d need to do experiments at scales far beyond anything we have the technology to probe (higher energies, smaller lengths, etc.). In this case, it’s good to have a handful of people continue to work on it, just in case they do come up with some clever new experiment that can give meaningful results, but until that happens, it’s probably not worth wasting too much time on it, for the vast majority of scientists.
3: There are some physical models (often called “toy models”) which are known right from the start to not actually describe anything in the real world. But these toy models are still valuable both for teaching physics students the basic principles used in the real models, in a simplified setting. Sometimes, they’re even used by researchers on the cutting edge, in order to develop these basic principles. We don’t “accept” such models, but we play around with them anyway.
I think you hit your automatic creationist response button by mistake. No one here is talking about random guesses with no proof.
Are you claiming that a theory can be a hypothesis with a good PR firm? I already addressed why string theory is not like evolution or gravity.
Actually I like Chronos suggestion of string model quite a lot, and I’ll use that from now on.
Voyager, read the OP. He specifically says “are these no different than fath/the root of religion?” So he does think something like “random guesses with no proof.” And I certainly don’t have an automatic creationist response button. Go back and read all my posts to the SDMB. I basically don’t even bother with creation/evolution threads, since they bore me.
And yet the history of science, especially physics, is replete with scientists trying to tease out of the confusing equations some model they can relate to. Quantum physics just turns out to be one where it’s really hard to do so. No doubt this will be a continuing trend, as we venture even farther from where common sense makes sense.
I used to wonder, “Why didn’t they just let the data and the emergent equations speak for themselves?” But it was very naive of me; the visualizations led to questions that solved the riddles. For example, Maxwell used physical analogies to synthesize the disparate lumps of knowledge known as “electrical studies”. Analogies he knew would be inaccurate, but which helped him and others see new connections between competing theories and contradictory experiments, and led to 4 equations that completely characterize electromagnetism.
To be fair, maybe the theory mentioned in this post is an example of unprovable science that can be dismissed.
But it’s also not clear what the state of the terms “theory,” “science,” and “provable” are for a paper on the universe being a computer simulation. If other scientists have to work to show the flaws, then isn’t it just plain science no matter how flawed it is? But I’ve never read Tipler’s original papers and undoubtedly couldn’t if I tried. They may be sheer gibberish, even though published in actual journals. My point is that above a certain level only a tiny elite few can have an opinion that matters, which means dismissing out of hand is no longer an option.
Apparently quantum computers can be seen as evidence for alternate timelines/universes… perhaps quantum interference involves interaction between nearby timelines…
Quite the contrary. Mendeleev based his periodic table on a shitload of observational data - basically everything known at the time about the atomic wights and chemical properties of the then known elements (which was most of them) - and a minimum of very simple mathematics (little more than the 8 times table). It was able to predict the existence of several new elements, including their rough atomic weights and their general chemical properties.
I’m not sure I see how that’s possible… Less facetiously, if such a thing were indeed the case, I’d say it would just establish the inability of the human mind to understand the world (which is a possibility, I guess). So in that case, the whole framework of theory and falsification, which is anthropocentric of necessity, would simply not apply anymore.
No, it’s just a little something that popped into my mind reading the thread. I think the ordinary view is that any theory of everything would make predictions of the form ‘such-and-such is the case’, which can be obviously falsified by checking and finding that such-and-such is, in fact, not the case. But this need not necessarily be the case, I think.
Note that this is not a view that is shared by the majority (or even a sizable fraction) of researchers in the field. The question of where the quantum speedup comes from is still an open one, but several other explanations besides parallel distribution across distinct universes have been proposed.
Maybe you should quote the OP when you respond 30 posts down the thread. Not that the OP ever said theories are random. The real confusion in the OP is between things unprovable in principle and things unprovable today - which is what many of the responses addressed. Faith was not really mentioned outside of the title.
And my creationist comment was meant to say a response to creationists, not a creationist response. I’ve seen plenty of creationists to whom your response would be right on the money. The OP is exactly the opposite of that.
