Is "String Theory" essentially just unprovable mathematical noodling?

[astro]

Does this physicist (Krauss) have a point?

Theory of Anything? - Physicist Lawrence Krauss turns on his own.

That’s easy to accept. But for the math to work, there also must be more physical dimensions to reality than the three of space and one of time that we can perceive. The most popular string models require 10 or 11 dimensions. What we perceive as solid matter is mathematically explainable as the three-dimensional manifestation of “strings” of elementary particles vibrating and dancing through multiple dimensions of reality, like shadows on a wall. In theory, these extra dimensions surround us and contain myriad parallel universes. Nova’s “The Elegant Universe” used Matrix-like computer animation to convincingly visualize these hidden dimensions.

Sounds neat, huh—almost too neat? Krauss’ book is subtitled The Mysterious Allure of Extra Dimensions as a polite way of saying String Theory Is for Suckers. String theory, he explains, has a catch: Unlike relativity and quantum mechanics, it can’t be tested. That is, no one has been able to devise a feasible experiment for which string theory predicts measurable results any different from what the current wisdom already says would happen. Scientific Method 101 says that if you can’t run a test that might disprove your theory, you can’t claim it as fact. When I asked physicists like Nobel Prize-winner Frank Wilczek and string theory superstar Edward Witten for ideas about how to prove string theory, they typically began with scenarios like, “Let’s say we had a particle accelerator the size of the Milky Way …” Wilczek said strings aren’t a theory, but rather a search for a theory. Witten bluntly added, “We don’t yet understand the core idea.”

It’s not just scientists like Krauss who stands to lose from this; it’s all of us. Einstein’s theories paved the way for nuclear power. Quantum mechanics spawned the transistor and the computer chip. What if 21st-century physicists refuse to deliver anything solid without a galaxy-sized accelerator? “String theory is textbook post-modernism fueled by irresponsible expenditures of money,” Nobel Prize-winner Robert Laughlin griped to the San Francisco Chronicle earlier this year

[Little_Nemo]

My understanding it that there are a number of observed phenomena that cannot be explained by existing theories like relativity and quantum mechanics; so obviously these theories are not complete. String theory can explain all observed phenomena; so it may be correct. However, nobody has figured out a way to test the theory to prove it’s correct. Arguably a different theory might also explain these same observed facts.

As for the idea that string theory is pointless because it hasn’t led to new technology, I’d offer the counter-argument that neither has the theory of gravity but nobody is disputed it’s real.

[Cisco]

@Little Nemo

As for the idea that string theory is pointless because it hasn’t led to new technology, I’d offer the counter-argument that neither has the theory of gravity

:dubious: Could we have gone to the moon, launched satellites, etc., without it?

[Blake]

@Little Nemo

My understanding it that there are a number of observed phenomena that cannot be explained by existing theories like relativity and quantum mechanics; so obviously these theories are not complete. String theory can explain all observed phenomena; so it may be correct. However, nobody has figured out a way to test the theory to prove it’s correct. Arguably a different theory might also explain these same observed facts.

Yes, the Invisible Pink Unicorn Theory for example. It can also explain all observed phenomena, and also has the flaw that nobody has figured out a way to test it. This is the whole point of the OP. String theory doesn’t appear to be anymore scientific than a religious explanation.

As for the idea that string theory is pointless because it hasn’t led to new technology, I’d offer the counter-argument that neither has the theory of gravity but nobody is disputed it’s real.

As Cisco points out, our entire exploration of space and utilisation of sattelite communications has hinged on a working theory of gravity.

[Evil_Captor]

I always firgured there was something fishy about string theory – thats why I never swallowed it, hook, line and sinker. Now, Rod Theory, thats a whole 'nother kettle of fish.

[The_Tooth]

I didn’t know the purpose of string theory was to delivery new technology. I thought it was to eliminate the discrepancies between Relativity and Quantum Theory on the subatomic scale.

I won’t pretend to a lot of knowledge about string theory, but I do know that it suggests subatomic particles aren’t irreducible. Of course it’s going to take a great deal of energy to break quarks apart, the forces holding them together are strong enough to make grown men weep. Given that, criticizing the fact that it would take a serious particle accelerator to test the hypothesis makes no sense to me.

[Marley23]

@Blake

Yes, the Invisible Pink Unicorn Theory for example. It can also explain all observed phenomena, and also has the flaw that nobody has figured out a way to test it. This is the whole point of the OP. String theory doesn’t appear to be anymore scientific than a religious explanation.

This is a little presumptuous, isn’t it? How much do you know about string theory?

As Cisco points out, our entire exploration of space and utilisation of sattelite communications has hinged on a working theory of gravity.

…hundreds of years after a working theory of gravity came about, yes.

[Blake]

@Marley23

This is a little presumptuous, isn’t it?

How is re-staring what is quite clearly written in the OP in any way presumptuous?

…hundreds of years after a working theory of gravity came about, yes.

Oh I see, so an application is only an application if its arrived at in less than 5 minutes after the theory itself, is that it? I’m not sure how you arrived at that conclusion.

[Marley23]

@Blake

How is re-staring what is quite clearly written in the OP in any way presumptuous?

It sounds like scientists have gone too far with string theory since they have so little to base it on; I just don’t feel qualified to say it’s nothing but a religion.

Oh I see, so an application is only an application if its arrived at in less than 5 minutes after the theory itself, is that it? I’m not sure how you arrived at that conclusion.

That’s because I didn’t arrive at it. I was saying that if gravity didn’t produce those results for quite some time, Krauss’s technology comment may not stand up.

[Blake]

@Marley23

I just don’t feel qualified to say it’s nothing but a religion.

That’s nice. Neither did anyone else.

That’s because I didn’t arrive at it. I was saying that if gravity didn’t produce those results for quite some time, Krauss’s technology comment may not stand up.

Krauss’s only comment was that if this ‘theory’ isn’t scientific, and thus cannot produce results, then we all stand to lose. What part of that doesn’t stand up because gravity did produce results?

[Little_Nemo]

We work with gravity, but we can’t really prove it exists. All we know is that we observe certain things happening and we have a theory about why they happen. But for all we know, the reason objects attract each other based on their masses might be that Invisible Pink Unicorns are pushing them together. Actual gravitons, like strings, have never been directly observed.

As for string theory, I agree it may be wrong. But it’s the simplest existing explanation of why things happen the way we observe them happen. So it’s more than just a whimsical notion.

[Marley23]

@Blake

That’s nice. Neither did anyone else.

@Blake

String theory doesn’t appear to be anymore scientific than a religious explanation.

I paraphrased you in too few words, but I don’t think this is a big difference.

[Liberal]

@Little Nemo

String theory can explain all observed phenomena; so it may be correct.

I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appear to be able to explain practically everything that happened within the fields to which they referred. The study of any of them seemed to have the effect of an intellectual conversion or revelation, open your eyes to a new truth hidden from those not yet initiated. Once your eyes were thus opened you saw confirmed instances everywhere: the world was full of verifications of the theory. Whatever happened always confirmed it. Thus its truth appeared manifest; and unbelievers were clearly people who did not want to see the manifest truth; who refuse to see it, either because it was against their class interest, or because of their repressions which were still “un-analyzed” and crying aloud for treatment.

The most characteristic element in this situation seemed to me the incessant stream of confirmations, of observations which “verified” the theories in question; and this point was constantly emphasize by their adherents. A Marxist could not open a newspaper without finding on every page confirming evidence for his interpretation of history; not only in the news, but also in its presentation — which revealed the class bias of the paper — and especially of course what the paper did not say. The Freudian analysts emphasized that their theories were constantly verified by their “clinical observations.” As for Adler, I was much impressed by a personal experience. Once, in 1919, I reported to him a case which to me did not seem particularly Adlerian, but which he found no difficulty in analyzing in terms of his theory of inferiority feelings, Although he had not even seen the child. Slightly shocked, I asked him how he could be so sure. “Because of my thousandfold experience,” he replied; whereupon I could not help saying: “And with this new case, I suppose, your experience has become thousand-and-one-fold.”

[…snip…]

With Einstein’s theory the situation was strikingly different. Take one typical instance — Einstein’s prediction, just then confirmed by the finding of Eddington’s expedition. Einstein’s gravitational theory had led to the result that light must be attracted by heavy bodies (such as the sun), precisely as material bodies were attracted. As a consequence it could be calculated that light from a distant fixed star whose apparent position was close to the sun would reach the earth from such a direction that the star would seem to be slightly shifted away from the sun; or, in other words, that stars close to the sun would look as if they had moved a little away from the sun, and from one another. This is a thing which cannot normally be observed since such stars are rendered invisible in daytime by the sun’s overwhelming brightness; but during an eclipse it is possible to take photographs of them. If the same constellation is photographed at night one can measure the distance on the two photographs, and check the predicted effect.

Now the impressive thing about this case is the risk involved in a prediction of this kind. If observation shows that the predicted effect is definitely absent, then the theory is simply refuted. The theory is incompatible with certain possible results of observation—in fact with results which everybody before Einstein would have expected. This is quite different from the situation I have previously described, when it turned out that the theories in question were compatible with the most divergent human behavior, so that it was practically impossible to describe any human behavior that might not be claimed to be a verification of these theories.

[…snip…]

One can sum up all this by saying that the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.

Sir Karl Popper, Conjectures and Refutations

http://www.stephenjaygould.org/ctrl/popper_falsification.html

[Blake]

@Little Nemo

We work with gravity, but we can’t really prove it exists.

You seem to have it backwards. An entity isn’t scientific because we can prove that it exists. It’s scientific because we are able to prove that it doesn’t exist but have consistently failed to do so.

Nobody has seen a graviton, but nobody has seen an atom or ionising radiation produce a mutation for that matter. We simply infer those things exist from the effects they produce.

That’s one of the great strengths of science. We don’t need to observe anything directly to credit its existence. Instead we are able to credit an entity by observing the effects, and then predicting what the other effects we should see if such an entity does exist, or else what effects couldn’t exist in a universe without such an entity.

Gravity itself, as mass attracts mass proportional to distance, is scientific because it can be easily tested and falsified. Relativistic explanations of gravity can also be tested to some extent through the observation of lensing, a predicted outcome. I’m not sure of the status of gravitons specifically but gravity waves are scientific because they have formed the basis of numerous falsifiable predictions. Those predictions have so far failed to produce the expected results, possibly because the equipment isn’t sensitive enough, but that’s irrelevant. The theory is scientific because it is open to falsifications and it makes testable predictions. It might be wrong, but it’s still scientific.

You can see how that differs form positing supernatural unicorns as our entity. What predictions can you make regarding an IPU? How can you falsify the existence of an IPU? Even if the IPU theory is right, it still won’t be scientific if it can’t do either of those things.

As for string theory, I agree it may be wrong. But it’s the simplest existing explanation of why things happen the way we observe them happen. So it’s more than just a whimsical notion.

Can you explain to a layman like myself why string theory is simpler than IPUs at explaining why things happen? It seems to me that the IPU theory only needs to posit one additional entity to explain all observations. String theory seems to need to posit umpteen entire dimensions to explain the observations. Doesn’t that make IPU theory simpler?

Of course if string theory is capable of making testable predictions then of course that trumps all. That makes string theory scientific. But if all we have are two competing non-scientific theories then you can’t claim that the one that seems most like science (and hence most psuedo-scientific) is simpler when it clearly isn’t.

@Marley23

I paraphrased you in too few words, but I don’t think this is a big difference.

If you don’t think there’s a big difference between “genetics is nothing but a religion” and “the genetic explanation doesn’t appear to be any more scientific than a religious explanation” then you are beyond my help I think. Just don’t repeat your assertion that I claimed that string theory was a religion. It’s just a silly strawman.

[DSeid]

Does it make testable and falsifiable predictions?

Some say yes. At least the bits about extra dimensions. http://particle.physics.ucdavis.edu/Physics/extradim.html

What is most exciting about this development is that when realistic models are built that incorporate such branes there are often experimental signatures that can be seen at current and upcoming experiments. These signatures range from observing a change in the strength of gravity at sub-millimeter distances in table-top experiments to the production of gravitons with momentum in an extra dimension at colliders. There are also important effects in cosmology which is about to undergo its own revolution due to an upcoming abundance of satellite data on the cosmic microwave background.

It is this potential for verification or elimination by experimental data that is fueling the drive to understand the new possibilities of extra dimensions.

[Larry_Borgia]

I’m not really qualified to discuss string theory, but it seems to me from what I’ve read that string theory arises from various well confirmed scientific theories like quantum mechanics and relativity, and is much less ad hoc than an Invisible pink unicorn theory. The theory is mathematically consistent, again AFAIK, and aspects of it can be explored through mathematics.

Even Brian Greene, string theory’s biggest booster in the popular media, admits and laments the fact that we cannot as yet empirically test string theory. But why should that mean that the attempt to construct the theory using mathematics is somehow invalid? As long as string theorists are honest about what they’re doing and don’t pretend that their theories are as well confirmed as Quantum Mechanics, where’s the harm. String theory may be testable someday. Why not have a well developed theory ready for that happy day? I’m a big fan of Popper, but I think he’d roll over in his grave if he knew that his criteria of demarcation was being used to stifle intellectual inquiry. Just because something’s pre-scientific doesn’t mean it isn’t interesting and worthwhile.

[Digital_Stimulus]

@Larry Borgia

The theory is mathematically consistent, again AFAIK, and aspects of it can be explored through mathematics.

Indeed. One valuable role philosophy can play in scientific theory is to provide insight into what can and cannot be a part of the theory. That is, make sure the theory is logically consistent. In just the same way, I think it’s been established that QM and such are not enough to explain the natural world. String theory and it’s accompanying mathematics, as I am given to understand, might be enough to provide such a consistent system, tested or not.

[Dr.Love]

@Physicist Lawrence Krauss

That is, no one has been able to devise a feasible experiment for which string theory predicts measurable results any different from what the current wisdom already says would happen. Scientific Method 101 says that if you can’t run a test that might disprove your theory, you can’t claim it as fact.

It seems to me that this is not sufficient evidence to claim that String Theory is not a scientific theory. What String Theory has done so far is come up with an alternate mathematical model for explaining the current experimental observations, which may eventually turn out to produce predictions of its own. I would propose that an alternate mathematical, even one that does not make predictions beyond the current model, is as much a scientific theory as the original model.

Consider Richard Feynman’s “sum-over-paths” model for explaining the movement of quantum particles. Without going into any of the details of the theory (which are superfluous to this discussion), Brian Greene in The Elegant Universe makes this comment (pg 108)

@Brian Greene

Feynman was one of the greatest theoretical physicists since Einstein. He fully accepted the probabilistic core of quantum mechanics, but in the years following World War II he offered a powerful new way of thinking about the theory. From the standpoint of numerical predictions, Feynman’s perspective agrees exactly with all that went before. But its formulation is quite different.

Italics in original. From what I can tell, Feynman’s method is subject to the same criticism as String Theory: that it produces no new experimentally verifiable predictions. If the String Theorists are not practicing physics (or science) as some claim, would they say the same of Feynman?

[smiling_bandit]

String Theorists do understnd te limits of their argument, and it frustrates the pie out fo them. Right now, however, we can’t come up with something better. At this point, we are pretty much beyond almost all practically observable phenomena.If we want to move forward on even small matters, we may need to build particle acelerators the size of small cities. And that’s just not practical.

[Larry_Borgia]

Having read the OP’s linked article I’d say it’s author really needs to switch to decaf.