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Hit_Sqd_Maximus

String theory and m theory

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Where's the relevance in finding a new quark that's charmed, strange and up. Whoa, what a discovery. What is the value for man kind in that? I don't get the value of this reductionist approach to physics.

Thats an incredibly naive statement, its thinking like that 'I don't need to know so I don't want to find out' that led to the dark ages! Have you ever heard the phrase 'Knowledge is power'? It's impossible to know that the discovery of these kooky quarks won't be incredibly useful in the future, even though its inconceivable now. Plus you cannot know that something they discover in one of these experiments could help them to better understand these particles, let alone provide a viable hypothesis for a Grand Unified Theory.

BTW I do agree with you about getting theoretical physicists to do some real work instead of crashing atoms and staring into their tea leaves to find an explanation why x has happened!! Bloody slackers!!

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In an ideal world with endless of funding, I would not have anything against them building as many accelerators as they want. In the real world however there is a limited amount of money given to basic science research. So the question that has to be asked is if it's worth to pour down billions of euros to build huge accelerators only to find the 160th meson that has already been predicted by the standard model? I say that there are far more worthwhile projects that should have more funding.

Now I'm not saying that all particle physics experiments should be shut down - there are projects there of geat value (chasing down the graviton, antimatter experiments etc). However experiments with the aim of adding yet another particle to the overcrowded particle zoo are just a waste of money that could be invested in other areas of physics/science that really could use the money.

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The particle accelerators have a use in biology as well. Esquisitely accurate three dimensional pictures of biomolecules can be generated with them. And since in protein chemistry form IS function, these three dimensional pictures of proteins help us understand molecular biology.

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Quote[/b] ]I never said anything about the standard model having that aim. I said that string theory had and if they want to keep their credibility they have to let go of their attachment for the standard model.

Sorry, but I think you have a very skewed view of the Standard Model and especially about the relation between the Standard Model and String theory:

Quote[/b] ]Why did I not like it?

1) The idea of having six quarks + six leptons plus the four force carriers seems more like biology than proper physics to me. It's phenomenology and not a nice general model like for instance GR or electromagnetic field theory. This is a vague argument, yes, but I'm a believer of symmetry in the

nature and I have a hard time believing that anything could be so ugly as the standard model. Why are there three generations of matter?

2) It can't predict particle masses. This is a good indicator of an incomplete theory. The mass patterns of the particles have no correspondence whatsoever to the categorization that the standard model predicts.

3) Can you say "dark matter"?

I totally agree about the masses and the generations, these are unsolved mysteries and there exists no proven theory to explain them. Nevertheless, the Standard Model is much more symmetric than any preceding theory in that it achieved the unification of the electromagnetic and weak force, just like Maxwell was able to unify the electric and magnetic force.

Also, I don't understand why you blame the existence of all the quarks and leptons on the Standard Model. They are observed in experiment. There is no way around them. There exist theories in which leptons and quarks are built up from even more fundamental particles but there does not exist any eperimental hint for that.

In string theory, particles are interpreted as 'vibrations' (of different frequencies) of strings.

You blame the Standard Model for not being symmetric. Again, this is an expression of the world we currently observe. The general opinion is that the world is very symmetric at high energies (e.g. in the Big Bang) but at 'colder' times like ours, the symmetry is broken. This is the approach of all Grand Unified Theories. There, it is assumed that at high energies, only one type of force exists, but, alas, at our own energy, this is not the case:

GUT force -> Electromagnetic x Weak x Strong x Gravity

As all science, everything is work in progress. There exist dozens of theories, but to explain particle physics phenomena the Standard Model is still state of the art (except neutrino oscillations).

Also, you keep saying that string theory is designed to keep the Standard Model alive. Like I said, this is necessary to explain existing data. On the other hand, this is not true because string theorists have a hard time to actually achieve that. It would be a big breakthrough to explain the Standard Model from String theory. This has not happened yet. The big problem again is that string theory is a theory of high energies and it is diffcult to close the gap with our energy regime.

Quote[/b] ]And I guess that's what bothers me - it's a very narrow minded theory. No matter how good the SM is for particle physics, there is more to the world then just the standard model. And building a theory of everything exclusivly around the standard model is well, plain wrong.

String theory is not built around the Standard Model. It is built to combine the Standard Model with GR, the two currently most fundamental (and tested) theories existing.

You have to accept that every theory/model has its scope. GR describes gravity on large scales, the Standard Model describes all other forces on small scales.

If you accuse the Standard Model for being narrow-minded you would have to say the same for GR. Sorry, but maybe we are too stupid...we haven't been able to figure out the connection yet.

Quote[/b] ]Millimeter scale? Hehehe. Call me when you get down to 6.62e-34 J/s. Then we can talk on small scale. Millimeter scale is no different than interplanetary distances for QM.

String theories predict additional dimensions that could change gravity on millimeter scales, hence one is checking this distances. This has nothing to do with QM.

Quote[/b] ]A bit offtopic, but I've always wondering how the hell they manage to get funding for such projects. Huge accelerators that cost billons of euros to build that not so seldom only serve to track down one or two hypothetical particles. Where's the relevance in finding a new quark that's charmed, strange and up. Whoa, what a discovery. What is the value for man kind in that? I don't get the value of this reductionist approach to physics.

If you judge science by its immediate value to mankind (maybe measurable in monetary profit?) then fundamental science is always useless. Thats very narrowminded I would say because you can never be sure whare you will be able to use your knowledge. Of course, one can always argue what kind of science is more necessary/useful at a time and how the findings should be shared, but I won't go into that. I'm too biased here.

Quote[/b] ]There's a shitload of data already on elementary particles. Stop building bloody accelerators and take a paper and a pencil and make a proper theory about them instad. Invest the money in telescopes or something. Or even better in pencils and papers for theoretical physicists.

Sorry, but absolute bullshit. We need much more experimental data. As said, there exist dozens of theories created and enhanced by thousands of theorists. What we need are experiments to check their predictions. All that shitload of data on elementary particles up to now only teaches us one thing: The Standard Model explains them very well tounge_o.gif, and this is making us theorists mad like hell crazy_o.gif.

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Also, I don't understand why you blame the existence of all the quarks and leptons on the Standard Model.

I blame the standard model for encouraging that view. String theory is a bit better in that respect, where you can get any particle by a general superposition of harmonics. However it does it at the cost of not making any sense for GR. This is the situation:

1) The partricle zoo, supported and predicted by the standard model.

2) Physicist realize that it isn't so nice so they invent the string theory to serve as a general model. Particle zoo problem solved.

3) The string theory works fine as a replacement for the standard model, but it gives awful results in GR.

I blame the string theory for trying too hard to make a nice replacement for the standard model, at the cost of ruining GR and other areas of physics.

Quote[/b] ]String theory is not built around the Standard Model. It is built to combine the Standard Model with GR, the two currently most fundamental (and tested) theories existing.

But that is exactly the problem. It makes a half-assed job with GR, just to make the particle physics nice. GR and SM are not equal partners in string theory. SM gets the nice theory and mathematic construction while GR takes the not-so-nice conequences.

Quote[/b] ]If you judge science by its immediate value to mankind (maybe measurable in monetary profit?) then fundamental science is always useless. Thats very narrowminded I would say because you can never be sure whare you will be able to use your knowledge.

No, I'm saying that there is a lot of fundamental research that needs funding and that I don't understand why particle physics gets so much cash when:

1) It's bloody expensive to build accellerators

2) They're most of the time using them to once again prove the standard model right.

Quote[/b] ] All that shitload of data on elementary particles up to now only teaches us one thing: The Standard Model explains them very well

Exactly, so why do you need another 10000 expreiments to show again that the standard model works. Get over it. We know that. Now it's up to you theorists to make a different interpretation and make sense of the data. I don't exaclty know what knowledge you expect to gain by tracking down another meson that you already knew would exist. What is the point? It's equally pointless as counting to a million by hand. You know that the next number is n+1, no sense in wasting time and money on it.

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Quote[/b] ]I blame the string theory for trying too hard to make a nice replacement for the standard model, at the cost of ruining GR and other areas of physics.

AFAIK, string theory allows the construction of a renormalizable quantum gravity theory from which GR emerges in the classical (i.e. non-quantum) limit. I wish string theory would be as straightforward as this explaining the Standard Model.

Quote[/b] ]Exactly, so why do you need another 10000 expreiments to show again that the standard model works. Get over it. We know that. Now it's up to you theorists to make a different interpretation and make sense of the data. I don't exaclty know what knowledge you expect to gain by tracking down another meson that you already knew would exist. What is the point? It's equally pointless as counting to a million by hand. You know that the next number is n+1, no sense in wasting time and money on it.

It's not about tracking down another meson (although there is still a lot of stuff to be measrued in the Standard Model). It's about getting the particles to higher energies to probe smaller scales. Thats where new discoveries can be made, and thats why we need more powerful accelerators. Your analogy to counting numbers is absolutely pointless. As I said, we need data at higher energies to check theories with it.

Last year, LEP at CERN saw the first hints of the Higgs particle (the only undiscovered Standard Model particle), but was disassembled for the construction of the Large Hadron Collider. Personally, I hope one will find supersymmetric particles there.

Accelerators are not the only way to probe physics beyond the Standard Model, though. Another strategy (cheaper but not as conclusive) is to measure well known physics parameters (like magnetic moments of neutrons or electrons) to extremely high precision. Effects from 'unknown physics' can also enter there.

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