Just to complete the topic of the SM
I quote from a famous Roger Penrose's book
By the way he is against the string theory
Not only he is also against the opinion that modern physics is pure math

I own the italian text , sorry for the poor traslation

chapter 25.8 Beyond the standard model ?

" It is evident that SM can not be the final answer as far as the physics of the particles are concerned.
It contains many non explained parts
....
It includes about 17 parameters which must simply be taken from experience
( Such as the Cabibbo and Weinberg angles, the lepton and quark masses and a certain number of other characteristics)..."

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However I do not understand why you dont accept that the new generation particle accelerators can cast a light also on this theory,
It is a very well known fact.

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Simple. Because I'm a physicist and I know what the new particle accelerators can and cannot do.
As any scientist, I admit I could be wrong but ONLY in light of evidence.
Thus you will have to present me with an experiment that will be conducted at CERN with the LHC which will directly (not indirectly) deal with String Threory. AFAIK (and that's the important part here), AFAIK all the experiments mean to strengthen the SM, not Strings.

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It is evident that SM can not be the final answer as far as the physics of the particles are concerned.
It contains many non explained parts

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Agreed. But this is a far cry from saying that SM is wrong, or made up, or that scientists tweak it to make the math work. Obviously SM isn't the final answer anymore than Newton was the final answer or Einstein is the final answer. Lord Kelvin made a famous statement in the late 1800's in from of the Royal Academy of Science after Maxwell's EM equations I belive stating that (paraphrase) "Science has discovered all there is to know... the rest is mere details".

It is folly to think that for a moment we have reached (or may ever reach) the "final answer" which is why theories like String Theory are worthwhile to examine. BUT this DOES NOT invalidate the theories in the energy realms where the theory focuses in. For example, Newton's gravity formulation is still accurate on Earth and at Sub Light speeds... merely because Einstein gave us more insight and showed divergence at high speeds does not mean that F DNE ma or that the kinematic equations are wrong.

Likewise with the SM. It is precisely accurate at the energy levels where it was discovered/made up. String theory aims to take it to realms where the SM doesn't work by design but that doesn't invalidate it.

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By the way he is against the string theory
Not only he is also against the opinion that modern physics is pure math

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I get the feeling we may be talking in circles for I agree completely with this (as can be seen in my previous posts). String theory is pure math and thus not physics. But what I'm saying is that SM is NOT pure math, it is based on experimental evidence, and thus is Physics!

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The SM originally included 17 particles but also a lot of parameters which must be set by experiment

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18 parameters. Not 17 Particles. Some of the parameters talk of how one particle interacts with another (couplings).

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these parameters were and they are still considered the weak point of the theory

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I don't see how you can say that. Are there unknowns in the theory? Yes. Like I've said, the mechanism by which the particles acquire mass, the Higgs Boson, is still suspect. Does that mean that SM is weak? Hardly. We know the mass of the electron, of the proton (and by inference of the quarks)... we know the interaction strength of particles, I mean we know so much from experiments that I would hardly call them the weak point of the theory.

It does have weak points, like renormalization, but it has nothing to do with the parameters which we have an experimental value for almost all of them.

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K can assume, 18 values given by the experience,see the attached table

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Ok mr Newton , your method is definitly a step forth vs the traditional astronomy but we feel that there is something wrong because you make use of too many parameters

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First off, I know that this is an off-the-cuff example, but let's be clear that science has no room for "feelings" or "popular vote". If the 18 values correctly predict the behaiviour, then you must find another theory that does the same (and better or more) before it will be replaced.

Secondly, your example is poorly constructed. The SM is not a case of ONE PARAMETER taking on 18 VALUES but rather of 18 PARAMETERS each with ONE VALUE...

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Moreover what's is the physical meaning of these 18 parameters ?

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...and 18 values that have clear physical meaning (as either a mass describing a particle or a coupling describing how the particles interact).

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To get rid of the 18 parametrs you must write the right equation ,than you would get one and one only value for K
However tha wrong equation is not completely wrong and , up to a certain extent, it might be of use.

This is the kind of arguments against Standard Model

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I think I'm starting to understand your point a bit better. I "think" you are confusing the acceptance of string theory with the rejection of SM. That's not the case. String theory does aim to reduce the 25 current parameters of SM into, ideally, one parameter. This is why it's called Grand UNIFIED Theory... it aims to unify all the forces. But this is NOT an arguement against the SM, merely an arguement that the SM is incomplete and is not accurate at all energy ranges. It's like I said in my post above: Relativity does not invalidate the Kinematic Equations we learn in Physics 101... it expands on them, gives them more solid meaning, and allows us to apply rules to domains where before we could not.

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The theory of the string tries to get rid of the multitude of parameters , whose physical meaning is definitly not clear, of the SM

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Again, I have to be very clear so that you walk away from this thread with at least this bit of corrected knowledge. The 25 parameters of the SM or NOT, I repeat, NOT physically unclear. We have a very good grasp on what their physical meaning is even if in some cases we don't know what the value is.

Frankly speaking your top down behaviour is a little bit irritating

"Simple. Because I'm a physicist ..."

A part from the fact that I my self hold a university degree in nuclear engineering , even though I do not dare to call myself a scientist and even more important I have never told anybody , here in this forum :

"Walk out .."

Apart from that, do you mean that Brian Greene is not a Physician , just because

" String theory is pure math and thus not physics "

What are you saying ?

"Relativity does not invalidate the Kinematic Equations we learn in Physics"

Once again what are you saying ?
Of course Einstein theory invalidates Newton physics
One thing is claiming that Newtonian physics is sufficiently accurate to send a rocket to the moon, an other thing is claiming that einstein's theory expands Newton's physics
It does not expands, it fixes some errors
Maybe these errors are negligible for 99.99 % of pratical uses but this is an other story

"Thus you will have to present me with an experiment that will be conducted at CERN with the LHC which will directly (not indirectly) deal with String Threory"

I suppose you are joking arent' you ?
A " direct" experiment ? in atomic physics ?
All the evidences in modern physics are bound to be "in direct" come on..
As I said and I repeat once again, if some new particles pop out and these particles have the characteristic expected by the theory than the theory ,is likely, true otherwise it is for sure false

"First off, I know that this is an off-the-cuff example, but let's be clear that science has no room for "feelings" or "popular vote". If the 18 values correctly predict the behaiviour, then you must find another theory that does the same (and better or more) before it will be replaced."

Thanks for clearing these concepts
You simply did not grasp the meaning of my example even though I can admit it is poor example
What do you mean for " Correctly predict " ?
A theory correctly predict , simply because :

a) The measuring instruments available at the time are not accurate
b) The domain of applications of the theory is limited

The same theory can miserably fails if you improve your measuring intruments and \ or you extend the domain of its application
However even in case a) and b) there is an other way to judge a theory
This method is not 100 % scientific but , sometimes, it works
If a theory is too complex , if it must introduce a lot of non clear parameters than probably there is something wrong even though the results are apparetly correct

You can like it or not but this is exactly the case of SM

SM is exceptionaly accurate ( in its domain of applications) but a lot of great scientists consider SM an " ugly " theory for the reason explained before

"The 25 parameters of the SM or NOT, I repeat, NOT physically unclear "

May be you did not notice that I quoted a certain Rogen Penrose on this specific topic

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Frankly speaking your top down behaviour is a little bit irritating

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Sorry? I don't know what "top down behaviour" means.
Are you sayig I behaieve like a quark that has a top-down to it (making me a spin zero, charge 1/2 quark)?

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Brian Greene is not a Physician , just because

" String theory is pure math and thus not physics "

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You infer incorrectly. Brian Greene is a physicist because he is ultimitely trying to find physical significance to the theory. String theory IS pure math and thus cannot be called Physics eventhough that is it's ultimate aim. Remember, Physics is not Math... Physics is the experimental verification of physical phenomena which can be expressed in math.

To be clear Brian Greene is a PHYSICIST because he is after physics but is using a purely MATHEMATICAL theory of String Theory to do it. Just because you use math makes you a Theoretical Physicists as opposed to those that work with experiments, experimental Physicists.

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Of course Einstein theory invalidates Newton physics

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Ummm, no. If it invalidated it, then we would be teaching Einstein exclusively in PHysics 101 and not Newton. To make invalid means that it is proven wrong in all regimes.

Examples of invalidating a theory:
Rotherfords atom scattering experiment INVALIDATED the Pudding-Pie model of the atom
Quantum Mechanics INVALIDATED the Bohr model of the atom.
Newton INVALIDATED Aristotles theory of the five elements and the four causes.

In all these cases, the new theory completely destroyed the old theory in all regimes. That is what it means to make a theory invalid. Newton is wrong only in high velocity regime (V~c), but below that (v<<c) it is perfectly valid.

Wikipedia puts it best:

"Well-established laws have indeed been invalidated in some special cases, but the new formulations created to explain the discrepancies can be said to generalize upon, rather than overthrow, the originals. That is, the invalidated laws have been found to be only close approximations (see below), to which other terms or factors must be added to cover previously unaccounted-for conditions, e.g., very large or very small scales of time or space, enormous speeds or masses, etc. Thus, rather than unchanging knowledge, physical laws are actually better viewed as a series of improving and more precise generalisations."

http://en.wikipedia.org/wiki/Physical_law

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Maybe these errors are negligible for 99.99 % of pratical uses but this is an other story

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No, that's the whole story. Newton will predict with as much accuracy as you want the collision of two billard balls. You do NOT need Einstein to understand that process perfectly. Still valid. Now when it comes to relatavistic collisions, then yeah, Newton is replaced by Einstein but we can still play Snookers on Earth!

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All the evidences in modern physics are bound to be "in direct" come on..

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Direct Evidence: a particle that doesn't have any of the other characteristics of any other particle pops out with the mass predicted for a Higgs Boson... direct evidence of the Higgs Bosons existence.

"Dr Renton, a particle physicist at Oxford, told BBC News Online.

"It's compatible with the Higgs boson certainly, but only a direct observation would show that."

http://news.bbc.co.uk/2/hi/science/nature/3546973.stm


Indirect Evidence: an interaction between two W,Z particles has the signature that is consistance with a Higgs Boson exchange... indirect evidence of the Higgs Boson existence.

"Dr Renton cites indirect evidence taken from observations of the behaviour of other particles in colliders that agrees with the figure of 115 gigaelectronvolts for the mass of the Higgs boson. "


http://news.bbc.co.uk/2/hi/science/nature/3546973.stm

Semantics at play here. NOBODY sees atomic particles of course! But we have aparatus that do the seeing for us instead. If these apartus "see" the paticle directly, we say that we have direct evidence... if thes apparatus instead "see" a related interaction that can only be explained (currently) by a particle, we say we have indirect evidence for it.

So for example, we have indirect evidence of the Higgs Boson's existence:

"In August 2000, physicists working at CERN's LEP saw traces of particles that might fit the right pattern, but the evidence is still inconclusive."

http://www.exploratorium.edu/origins/cern/ideas/higgs.html

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SM is exceptionaly accurate ( in its domain of applications) but a lot of great scientists consider SM an " ugly " theory for the reason explained before

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Right. We agree on this point. That SM is "exceptionaly accurate ( in its domain of applications)". The "ugliness" is a human concept that has proven a good guide, but it's not science nor reason to believe that SM is wrong. That is all I'm saying.

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"The 25 parameters of the SM or NOT, I repeat, NOT physically unclear "

May be you did not notice that I quoted a certain Rogen Penrose on this specific topic

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Maybe you are using "physically unclear" in a way I'm not used to. Roger Penrose's quote does not say that the parameters are unclear, merely that the SM model is incomplete (which we all agree on). To state that a parameter is "physically unclear" means that we cannot assign it physical significance (such as energy, mass, velocity, etc).

All 25 parameters are one of two things: either a mass (which reflects that particles resistance to inertia) or a coupling (which reflects how two particles interact). They are very physically clear even if we don't have a value for it.

Some words more about the possibility to test the String theory in the last generation particle accelerators

String scientits envisage 3 possibilities

a) what we call "particles" are nothing else that modes of vibrations of basic entities called strings.
Same as the string of a guitar the frequency of vibration depends upon the rigidity of the string and the rigidity depends also on length of the string
If the lenght of the string is not so small than high energy collisions should produce particles having mass of abt 1000 protons

This amount of energy will be available at LHC

By the way these "monsters" have been already found in the cosmic radiations


b) The gravitational force should increase at very short distances consequently, according to the calculus an high pressure should poduce " micro black holes " which last for a fraction of time and again yhey will produce new unknown particles

c) One of "untouchable" principle of physics could fail
The principle of conservation of energy
A portion of energy could , apparently, disppear in the hidden dimensions

The key issue is the size of the strings and of the hidden dimensions, assuming of course that they exist
According to the calculus,if this size is at the scale of Planck than LHC is sufficient if it is much smaller it is not

P.S.

About the supposed assumption that a " direct " prove is needed to confirm the theory of the strings
This is absolutly false

The "Quarks" have been introduced, at the very beginning, as mathematical entities
Even nowadays , nobody have yet " seen " a single quark
The Quarks come always togheter
You can directly measure, for example, the mass, of a proton but not of its quarks
Neverveles Quarks are , nowadays , considered real entitities simply because the predictions of the theory meet the experimental tests

Why should we deny, in priciple, that this can not happen also for the strings ?

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According to the calculus,if this size is at the scale of Planck than LHC is sufficient if it is much smaller it is not

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The plank scale is 10^19 GEV; LHC will produce at most 14 TEV or roughly 10^4 GEV.

Hence LHC (nor any future planned accelerator) will have enough energy to probe these lengths.

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micro black holes "

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There is a very, very, very, very small chance of this happening and no scientist at CERN seriously expects it to happen. And even if they did, this would be a confirmation of relativity and not String Theory (ie: micro black holes are fully explained with current theory).

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A portion of energy could , apparently, disppear in the hidden dimensions

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It "could". But then again this has been a possibility since the first collider and in fact is a possiblity in every experiment and interaction on Earth. Again, scientists at CERN do not expect this to happen nor is this something that is being tested.

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Even nowadays , nobody have yet " seen " a single quark

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Absolutley correct. Quarks "exist" merely by the indirect evidence of scattering experiments against Hadrons like protons and neutrons. There are in fact other competing theories for what is "inside" these particles but the math behind quarks accurates predicts the "particle zoo" and thus it's the theory that is used today. But you are absolutely correct; unlike other particles, we only know of quarks by indirect evidence.

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About the supposed assumption that a " direct " prove is needed to confirm the theory of the strings
[...] Why should we deny, in priciple, that this can not happen also for the strings ?

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I don't and never did. I never said that direct evidence was the only way to confirm a theory... but it is the only way that a theory becomes "solid". As you mention, Quarks are only indirect and thus while popular, there are still people working on alternatives. The majority of the SM is direct and thus there is little to no work on alternatives.

Now, if we had indirect evidence of a phenomena that could only be explained by String Theory, then that would be great! But the fact is that there is NO evidence currently, direct or indirect, and scientists would rather focus on what we can test (SM) rather than what we can't (Strings). But I do admit that because of the high energy regime that is string theory's domain, the first evidence of it's validity will most likely be "indirect".

I agree on the last two items but please accept that items 1-2-3 have be taken by " The fabric of cosmos .." by Brian Greene
He may be wrong but I dont suppose he tells nonsense

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I agree on the last two items but please accept that items 1-2-3 have be taken by " The fabric of cosmos .." by Brian Greene

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If you re-read my posts carefully, you'll note that I'm not denying that these facts are true (in the theoretical physics sense), merely that they are not facts that will be tested at CERN or anywhere else anytime soon. That's been my point all along: that there are no experiments in the works at CERN or elsewhere that can test the validity of String theory. Hence, String Theory remains a mathematical theory about physics instead of a Physical Theory using math.

I understood what you said but I repeat once again this is not Brian Green's opinion
I translate from the "factory of cosmos"

"If the strings were 10^-18 mt long , the mass of the particles which corrispond to the highest frequency vibrations would be hundreds or thousands protonic mass.
This energy level will be available when the new particle accelerator LHC at CERN is ready "

P.S

Before 1996 the dimensions of the strings were supposed to be about 10^-33 cm
if so no test would be possible ,the amount of energy being enormous