Why is string theory called a theory?

[parallaxicality]

After listening to Fraser's excellent podcast on the subject, I was a bit thrown by his lumping string theory together with such concepts as warp drive and white holes, essentially confining it to science fiction, albiet with numbers instead of words.

But if string theory has no evidence to support it, and is untestable, are we not doing science a disservice by calling it a theory rather than a hypothesis? Given that one of the principal attacks of creationism is to describe evolution, plate tectonics and the big bang as "just theories", is there not some danger in so cheapening the word by applying it to a concept with no evidence to support it?

[HenrikOlsen]

String theory IS a hypothesis.

[Argos]

The general public confuses 'hypothesis' with 'theory'. The expression String theory seems to be taylored for the public consumption. Yes, I´d call it 'string hypothesis'.

[hhEb09'1]

Given that one of the principal attacks of creationism is to describe evolution, plate tectonics and the big bang as "just theories", is there not some danger in so cheapening the word by applying it to a concept with no evidence to support it?I'm not sure what you mean. There's just as much evidence to support it as there is plate tectonics, it seems to me. In both cases, there are observables that are explained by the theory. Why is that not "evidence"?

[parallaxicality]

According to the podcast, all the evidence that supports string theory doesn't need string theory to explain it.

[01101001]

Wikipedia: Theory (http://en.wikipedia.org/wiki/Theory)


The term theory is occasionally stretched to refer to theoretical speculation that is currently unverifiable. Examples are string theory (http://en.wikipedia.org/wiki/String_theory) and various theories of everything (http://en.wikipedia.org/wiki/Theory_of_everything). In common speech, theory has a far wider and less defined meaning than its use in the sciences.

[hhEb09'1]

I don't think that wikipedia article is saying that "string theory" is common speech, and not of science.

Right?

[speedfreek]

I'm not sure what you mean. There's just as much evidence to support it as there is plate tectonics, it seems to me. In both cases, there are observables that are explained by the theory. Why is that not "evidence"?

There are many methods to test plate tectonics but none to test string theory.

For instance, if plate tectonics is at work on Earth, and we think South America and Africa were originally joined, we should find similar distributions of rock type along the facing coastlines of both continents - and we do (the fact they fit together so neatly is also a big clue!). We can find much evidence of plate tectonics on Earth, from fault lines causing earthquakes to mountain ranges being pushed up where different plates meet to new rock being formed in sub-oceanic ridges. Many different observations that can all be explained by plate tectonics.

So what observations do we have that can be explained by sting theory? If string theory is correct, what should we be able to look at to see evidence of that?

[HenrikOlsen]

We can also set up instruments to measure the actual movement, which is the conclusive piece of evidence.
The reason why we think the tectonic plates are moving is that they are actually measurably moving. :)

[hhEb09'1]

There are many methods to test plate tectonics but none to test string theory.I'm not addressing the weaknesses/strengths of string theory though, just whether it is appropriate to call it a theory. I think it is, and that the author of the wiki article does too, is all.

Frankly, I'm a little surprised at the vehemence about the issue, on both sides. I know that a lot of skeptics hammer away at the notion that certain things are "just" theories, but I think taking that objection seriously is just as bad.

OK, not as bad, just bad. :)

PS: My own response is usually along the lines of "well, I have this theory that the sun will come up tomorrow morning..." :)

[andyschlei]

I'm not addressing the weaknesses/strengths of string theory though, just whether it is appropriate to call it a theory. I think it is, and that the author of the wiki article does too, is all.

Frankly, I'm a little surprised at the vehemence about the issue, on both sides. I know that a lot of skeptics hammer away at the notion that certain things are "just" theories, but I think taking that objection seriously is just as bad.

If it is not testable, and may never be testable, is it a theory or just a bunch of complex math whose connection to reality is only one of faith?

I would agree that calling something "just theories" is a poor form of criticism. But an idea must meet some standards to be considered a theory. Since String Theory does not have a single agreed form (M-Theory, 4 forms, 10 dimensions or 11, etc.) and does not produce any testable results, it is not much of a theory. OTOH, it could be that, given its complexity, we just aren't far enough down the path and that it will settle down into an identifiable form and produce testable results (perhaps with help from the LHC?).

So I'll be wishy washy and vote "Theory Light"

[hhEb09'1]

Since String Theory does not have a single agreed form (M-Theory, 4 forms, 10 dimensions or 11, etc.) and does not produce any testable results, it is not much of a theory. Long before I'd heard of string theory, I was introduced to ring theory (http://en.wikipedia.org/wiki/Ring_theory). (There may have been an intermediate form called tring theory but I missed it.) A lot of your objections would probably apply to ring theory as well. But clearly, calling it ring theory light would be ridiculous. That's kinda my point, a lot of the heat generated on both sides of this issue is just contributing to the entropy of the universe.

[Peter Wilson]

Why is string theory called a theory?

Because they couldn't get funding if they called it by its real name?

[loglo]

Why is string theory called a theory?

Because its thin on prediction and long on speculation? :D

[hhEb09'1]

Because its thin on prediction and long on speculation? :DAnd that's why they call it Newton's theory of gravity?

[andyschlei]

Long before I'd heard of string theory, I was introduced to ring theory (http://en.wikipedia.org/wiki/Ring_theory). (There may have been an intermediate form called tring theory but I missed it.) A lot of your objections would probably apply to ring theory as well. But clearly, calling it ring theory light would be ridiculous. That's kinda my point, a lot of the heat generated on both sides of this issue is just contributing to the entropy of the universe.

So I admit that calling it "theory light" was a fairly large copout.

But we should admit that theories have different levels of development -- even of maturity. Perhaps early in its development, Einstein had some idea of the direction he wanted to go, but had not done all the heavy lifting to complete a full new theory of gravity that he eventually published as General Relativity. Some evidence to this effect is that he wrote about special relativity first.

So let's say that with String Theory, it is still quite young, and the math being so complex, it is taking more than one brilliant individual to bring it to fruition. Or that that brilliant individual hasn't finished yet.

So String Theory is a theory, but it is young and untested. It may disappear, it may break out into a fully formed, testable theory. We don't know.

And if it is a fad in Physics, that will take care of itself when someone publishes a breakthrough.

[Kaptain K]

From trinitree88's sig

A third rate theory forbids
A second rate theory explains after the fact
A first rate theory predicts...A. Lomonosov
By that definition, I would say that String Theory is a second rate theory, So far.

[parallaxicality]

Long before I'd heard of string theory, I was introduced to ring theory (http://en.wikipedia.org/wiki/Ring_theory). (There may have been an intermediate form called tring theory but I missed it.)

I've heard of that one. It's the controversial hypothesis that the foundation for all matter is in fact a small market town northwest of London. (http://en.wikipedia.org/wiki/Tring)

[hhEb09'1]

I've heard of that one. It's the controversial hypothesis that the foundation for all matter is in fact a small market town northwest of London. (http://en.wikipedia.org/wiki/Tring)D'oh

I guess I've just been out of it. After looking it up on google, it looks like the best evidence so far for tring theory is that Tring is the buckle of the London commuter belt. After all, it rhymes with bling. And it has a brewery.

[Peter Wilson]

I've heard of that one. It's the controversial hypothesis that the foundation for all matter is in fact a small market town northwest of London. (http://en.wikipedia.org/wiki/Tring)

I was pretty skeptical, but there it is:


It is located at the summit level of the Grand Unified Theory and there has been extensive excavation of cuttings for both the canal and railway as they pass through the vicinity.
:clap:

[hhEb09'1]

I was pretty skeptical, but there it is:That's weird, when I look at it, I see canals. Maybe this has something to do with Mars?

[parallaxicality]

And that's why they call it Newton's theory of gravity?

Newton's theory of gravity predicted Neptune. It also sent men to the Moon and back. It works to a point. It failed with Vulcan but then Einstein came along.

[Peter Wilson]

Experimental confirmation of String Theory (http://www.youtube.com/watch?v=GX4_3cV_3Mw)

Its about time!

[snowcelt]

String theory may be short on direct evidence; but it does seem to smooth out problems in our more classical theories. One example is the problem of point masses. The closer you get to a point mass the stronger gravity gets (inverse square law), until you reach infinite gravity. With a string there is no point mass; therefore, you avoid mathematical problems of manipulating infinities in your equations.

[Peter Wilson]

Isn't the "point-mass" a classical approximation?

Under Uncertainty Principle of QM, can we every really say all the mass of anything is in one point? I don't see how QM allows a finite mass to occupy zero volume of space.

[snowcelt]

Isn't the "point-mass" a classical approximation?

Under Uncertainty Principle of QM, can we every really say all the mass of anything is in one point? I don't see how QM allows a finite mass to occupy zero volume of space.

This is where I have a problem. If QM does not allow a point mass, what does it allow? String theory gives us a shape that is not a point. In QM the Uncertainty Principle does not give us any shape but what classical theory has left us, quarks and leptons which seem to be points.

[loglo]

And that's why they call it Newton's theory of gravity?

No..that is because it contains new tons. :)

[Peter Wilson]

:rolleyes:

[trinitree88]

So I admit that calling it "theory light" was a fairly large copout.

But we should admit that theories have different levels of development -- even of maturity. Perhaps early in its development, Einstein had some idea of the direction he wanted to go, but had not done all the heavy lifting to complete a full new theory of gravity that he eventually published as General Relativity. Some evidence to this effect is that he wrote about special relativity first.

So let's say that with String Theory, it is still quite young, and the math being so complex, it is taking more than one brilliant individual to bring it to fruition. Or that that brilliant individual hasn't finished yet.

So String Theory is a theory, but it is young and untested. It may disappear, it may break out into a fully formed, testable theory. We don't know.

And if it is a fad in Physics, that will take care of itself when someone publishes a breakthrough.

andyschlei;969615 :shifty: :naughty: :think: pete

[Hornblower]

So I admit that calling it "theory light" was a fairly large copout.

But we should admit that theories have different levels of development -- even of maturity. Perhaps early in its development, Einstein had some idea of the direction he wanted to go, but had not done all the heavy lifting to complete a full new theory of gravity that he eventually published as General Relativity. Some evidence to this effect is that he wrote about special relativity first.

So let's say that with String Theory, it is still quite young, and the math being so complex, it is taking more than one brilliant individual to bring it to fruition. Or that that brilliant individual hasn't finished yet.

So String Theory is a theory, but it is young and untested. It may disappear, it may break out into a fully formed, testable theory. We don't know.

And if it is a fad in Physics, that will take care of itself when someone publishes a breakthrough.

Very well said. I think we can find some good analogies in history by discussing the geometric models of the solar system as presented by Ptolemy, Copernicus and Tycho. In my opinion they can be regarded as theories because they are methodically derived from analysis of observable facts about the apparent motions of the planets.

For the sake of argument let's start with a hypothetical system in which all of the planets move in perfectly circular orbits. That greatly simplifies the math.

In Ptolemy's model each planet moves in an epicycle with a period of one year, the center of which moves around the Earth in a circle that is technically called the deferent.

Copernicus felt that Ptolemy's constructions were ad hoc for each planet and formed a scientifically untidy conglomeration. He sought a common thread for the entire system and showed that the epicycles could be accounted for by having all the planets, including Earth, revolving around the Sun in simple circular orbits.

Tycho and others noted that the Copernican version would show annual parallax of the stars unless they were at what was considered an outrageously large distance. Tycho proposed that the planets orbit the Sun, which in turn would be orbiting around the Earth. That would retain most of the coherence of Copernicus, while eliminating the stellar parallax objection.

These theories could not be tested by observation as of the year 1601, the year of Tycho's death. The stellar parallax we now know to be real was unobservably small at the time, but the only obstacle to observing it was technological, with no geometric objections in principle. Presumably an almighty Creator could place the stars at any mind-blowing distance He so wished, with total disregard of any mortal human being's belief about what is outrageous.

The laws of motion and gravitation as firmed up by Newton clearly favor Copernicus, but this understanding of the dynamics was still many decades in the future. When it finally emerged, the principle that started with Copernicus matured into a very robust theory that was overwhelmingly accepted by scientists before Bessel and others, with the help of powerful telescopes, finally succeeded in observing the stellar parallax, the one geometric detail that is a consequence only of Copernicus.

Perhaps string theory will evolve in a similar fashion and succeed in unifying gravity with the other forces, and quantum mechanics with relativity. We may need the mother of all atom smashers to test predictions which currently are unobservable but may not be objectionable in principle, and such a machine may be roughly analogous to Bessel's telescope.

[snowcelt]

A salute to the LHC (large Hadron Collider) which will help us see and understand basic physics. If the LHC finds the Higgs Boson (HB) the theory of symmetry will help pave the way for string theory.