• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

String Theory, summarized

Dave1001 said:
A side question. What exact education would one need to make an informed opinion on string theory? What math education, what physics education, what other education?
Click to expand...

In order to understand string theory from a physics perspective I think you'd need a basic understanding of the Standard Model, as well as some knowledge of the fundamentals of Quantum Mechanics.

Mathematically it's more complex. Statistics and probability are required to understand Quantum Mechanics. An understanding of calculus of multiple variables, along with partial differentials and ordinary differentials are necessary for many of the string equations. Also an understanding of methods of proofs and methods of approximation wouldn't hurt.

But in order to be a skeptic, I think you can understand the results well enough without all the math. The physics concepts can be readily explained in real world terms. Unfortunately, this can backfire. I almost became a string theory convert after watching NOVA's "The Elegant Universe", but when I dived back into the research I was readily convinced that the show was prematurely trumpeting M-theory as a solution to Unification and I was once again a skeptic.

And just in case anyone wondered, I classify myself as a string theory agnostic. I am mildly hopeful that someday I will be proven wrong, but I am not expecting a string theory rapture anytime soon, either.
 
HeavyAaron said:
When you have two hypothesis that predict the observations with equal accuracy you assume the simplier pending further observations. IMHO String Theories fail the simpliar tests. I suppose you could argue that they are more elegant. But it doesn't look that way to me. Of course, I don't have all the math skills required to fairly evaluate that.

Aaron
Click to expand...


I think we should be careful not to confuse "simple" with "elegant." Simple implies easily understandable, which is not what we always prefer in physics. Elegant implies explaining the largest number of observations with the fewest number of principles. These principles are not necessarily easily grasped. It's the elegant theories that tend to take the prize. Though the math involved in string theory is extraordinarily difficult, the idea is elegant. Unless some observation invalidates it, I don't see any reason to abandon it, if it has thus far worked in the predictions that it has made.

'Course, I'm hardly an expert either.
 
Zygar said:
But in order to be a skeptic, I think you can understand the results well enough without all the math. The physics concepts can be readily explained in real world terms.
Click to expand...

That's different from being able to make an informed opinion on string theory. Thanks for the detailed answer to my question though.
 
I don't quite understand some of the objections to string theory -- why should it matter if, in addition to making correct verifiable predictions that explain all the observations in question, it also produces predictions that are not verifiable? I don't get why this is a problem in practical terms. If the math works, and it doesn't get anything wrong, and it's elegant, seems to me it's a viable theory, with just a l'il added bonus...
 
Last edited:
Buckaroo said:
I don't quite understand some of the objections to string theory -- why should it matter if, in addition to making correct verifiable predictions that explain all the observations in question, it also produces predictions that are not verifiable? I don't get why this is a problem in practical terms. If the math works, and it doesn't get anything wrong, and it's elegant, seems to me it's a viable theory, with just a l'il added bonus...
Click to expand...

The problem is that it has made no verifiable predictions. See my above posts.
 
Zygar said:
The problem is that it has made no verifiable predictions. See my above posts.
Click to expand...

But if it absorbs the standard model, it does make predictions -- the same one the standard model does, right? If it's simultaneously more elegant, I don't see how a little extra flash hurts anything.

Of course, if either of these conditions aren't true then I'm certainly wrong. Are they false? (I'm not arguing, I really don't know.)
 
Last edited:
Buckaroo said:
But if it absorbs the standard model, it does make predictions -- the same one the standard model does, right? If it's simultaneously more elegant, I don't see how a little extra flash hurts anything.

Of course, if either of these conditions aren't true then I'm certainly wrong. Are they false? (I'm not arguing, I really don't know.)
Click to expand...

It technically doesn't predict the Standard Model. It was built after the fact. And technically the Standard Model is just a fancy way of connecting Quantum Mechanics and General Relativity together. So the predictions of it are actually from Quantum Mechanics and General Relativity.

However, it is not more elegant than Quantum Mechanics and General Relativity. It attempts to resolve the conflicts between the two, but in so doing it continually requires more and more complexity. There are mathematical inconsistencies popping up all the time. Many times these can be shown to be a result of a mistake due to the mathematical complexity, but sometimes the solution has been to add another dimension. In the early stages of the theory there were 10 dimensions (6 extra dimensions) required in order to make it work. But as more inconsistencies have been found, it has become necessary to add more dimensions! It is now up to 26 accepted dimensions! How is it more elegent to solve a mathematical equation by adding another dimension whenever there is an inconsistency?

All this aside, it still has glaring problems. The "extra flash" you are describing is one of them. It is so flexible it could be made to describe any number of universes. Does it describe our own? Who knows, since it is only one of the infinite possibilities of the math.
 
Buckaroo said:
But if it absorbs the standard model, it does make predictions -- the same one the standard model does, right? If it's simultaneously more elegant, I don't see how a little extra flash hurts anything.

Of course, if either of these conditions aren't true then I'm certainly wrong. Are they false? (I'm not arguing, I really don't know.)
Click to expand...

The problem is that any brand of string theory is unfalsifiable, i.e., it isn't science.

If a theory isn't falsifiable, it isn't subject to scientific experimentation. Again, it isn't science.

That's why so many critics of string theories dismiss them as philosophy.

We might as well be discussing metaphysics.

AS
 
Zygar said:
It technically doesn't predict the Standard Model. It was built after the fact. And technically the Standard Model is just a fancy way of connecting Quantum Mechanics and General Relativity together. So the predictions of it are actually from Quantum Mechanics and General Relativity.
Click to expand...
Why does it matter that string theory came afterwards? General relativity came after Newtonian gravity, and made it a special case. Nobody's calling GR bad science because of this. How is string theory different in this regard?
Zygar said:
In the early stages of the theory there were 10 dimensions (6 extra dimensions) required in order to make it work. But as more inconsistencies have been found, it has become necessary to add more dimensions! It is now up to 26 accepted dimensions! How is it more elegent to solve a mathematical equation by adding another dimension whenever there is an inconsistency?
Click to expand...
I think this boils down to a matter of taste. Are the infinite superpositions of states that you get out of QM more parsimonious than a string knotting up in 26 dimensions? I wouldn't interpret it that way.
AmateurScientist said:
The problem is that any brand of string theory is unfalsifiable, i.e., it isn't science.

If a theory isn't falsifiable, it isn't subject to scientific experimentation. Again, it isn't science.

That's why so many critics of string theories dismiss them as philosophy.

We might as well be discussing metaphysics.

AS
Click to expand...
Even granting Zygar's other criticisms, how still is it unfalsifiable? If it makes predictions about masses, charges, spins, etc. that can in principle be wrong, then this is certainly not so. Sounds to me like there are a fair number of physicists that think otherwise -- hence the comments from an earlier post about exploring the ideas once the super-duper accelerators come online.
 
Buckaroo said:
If it makes predictions about masses, charges, spins, etc. that can in principle be wrong, then this is certainly not so. Sounds to me like there are a fair number of physicists that think otherwise -- hence the comments from an earlier post about exploring the ideas once the super-duper accelerators come online.
Click to expand...

You seem to have missed that it makes no testable hypotheses that are not predicted by other theories. For example, Supersymmetry is the theory that predicts the different properties from the Standard Model for the Higgs boson and other particles. String theory is just sufficiently mathemetically elegent that it also describes Supersymmetry.

It is also sufficiently mathematically elegant that it can describe anything. That it why it is not falsifiable. It is no different from a religion or a philosophy in its current form.
 
Zygar said:
You seem to have missed that it makes no testable hypotheses that are not predicted by other theories.
Click to expand...

You're right. Reading back through the thread I see where I missed it. So the gist is this: since string theory can accomodate equally well e.g. two mutually incompatible models, it's practically useless?

Yep, I'll buy that. Thanks!
 
Zygar said:
You seem to have missed that it makes no testable hypotheses that are not predicted by other theories. For example, Supersymmetry is the theory that predicts the different properties from the Standard Model for the Higgs boson and other particles. String theory is just sufficiently mathemetically elegent that it also describes Supersymmetry.

It is also sufficiently mathematically elegant that it can describe anything. That it why it is not falsifiable. It is no different from a religion or a philosophy in its current form.
Click to expand...

This is just not true. As you yourself say, it makes predictions for the Higgs boson, as well as other particles. There are very clear predictions, of the Higgs mass for example, that are very different from the Standard Model. These predictions will start being tested within the next year at the LHC. Sting theory is entirely falsifiable, as are all theories that make predictions about particles with masses less than 1TeV. The fact that it also make untestable predictions is irrelevant until we reach the point where those are the only predictions left.

You are also wrong about supersymmetry and string theory. True string theory does not use supersymmetry at all. After the ideas of supersymmetry were developed, it was realised that much of the maths, as well as the underlying concepts, could also be used in string theory. As a consequence, both string theory and supersymmetry are obsolete, what is now commonly called string theory is actually supersymmetric string theory, and contains concepts from both earlier models.
 
Let's not forget that Ernst Mach divorced himself from the scientific community late in life because of all the idiots who were wasting their time with the completely unscientific and over-hyped "atomic theory."
 
Cuddles said:
This is just not true. As you yourself say, it makes predictions for the Higgs boson, as well as other particles. There are very clear predictions, of the Higgs mass for example, that are very different from the Standard Model. These predictions will start being tested within the next year at the LHC.
Click to expand...

Do you have any references about this subject? I haven't seen any experiments prepared that are not wholly based upon Supersymmetry. My understanding of the concepts at work is that Supersymmetry has a subset of seperate claims which are falsifiable and are based upon earlier work in the field of Quantum Mechanics. Particularly having to do with the development of theories surrounding quarks and the Higgs field. Basically Supersymmetry is a theory revolving around what sorts of bosons are possible in our universe. The current amalgamation of theories does merge these two theories, but string theory is not validated by the predictions of Supersymmetry alone.

As for Supersymmetric String theory, the currently accepted "super theory" is M-Theory, which is infact a merging of all accepted physics models. It's the "God" theory (in more ways than one). My above points stand with M-Theory because it is still based upon the string model, and is still unfalsifiable.
 
Psi Baba said:
Let's not forget that Ernst Mach divorced himself from the scientific community late in life because of all the idiots who were wasting their time with the completely unscientific and over-hyped "atomic theory."
Click to expand...

Agreed. That's why I am an agnostic in this case. Let the people who passionately believe in it figure out how to prove it. They just haven't, yet.
 
You must log in or register to reply here.

Back
Top Bottom