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The 18 constant of the standard model , same as the extra dimensions of the string theory ,apparently have no meaning at all



It was 18 before the discovery of the neutrino mass. Now it's 25:
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the mass of the up quark
the mass of the down quark
the mass of the charmed quark
the mass of the strange quark
the mass of the top quark
the mass of the bottom quark
4 numbers for the Kobayashi-Maskawa matrix

the mass of the electron
the mass of the electron neutrino
the mass of the muon
the mass of the mu neutrino
the mass of the tau
the mass of the tau neutrino
4 numbers for the Maki-Nakagawa-Sakata matrix

the mass of the Higgs boson
the expectation value of the Higgs field

the U(1) coupling constant
the SU(2) coupling constant
the strong coupling constant

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And they are nothing like the extra dimensions of String theory since these values are set by experiments and not arbritraraly determined.



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The scientits have tweaked, so to speak, the equations several times to make them compatible with the experience



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apparently have no meaning at all


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They have "simply " been introduced to make the results of the equations complying with the experience


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consequently modern physics is bound to be, up to a certain extent, pure math



Wrong on all counts. There is no tweaking these values and it's not pure math. They have been experimentally determined through the last 50 years of collider experiments. The equations have been modified to better fit the experimental results (for example using a U(1)xSU(2) grounp instead of an SU(3) group) but it makes sense that experiments guide the theoretical foundation when they are in disagreement. Contrary to popular belief, Physics is guided by experiments and not math. Math is merely one way for us to express what we find, to have a common language, but the "reality" of physics lies in the phenomenology, in what we observe happening in the world and not what we believe an equation tells us. It's only when the math and the experiment coincide that we start treating the math as real (as with the SM)... String theory is not there yet by a long shot.

This is why the SM is on such strong foundation because it has been tested and retested to a sick degree of accuracy and is very robust in it's current incarnation. It is absolutley wrong to think that scientists have just made up these masses so they work; each of the values above corresponds to a physical value which is again why the Higgs Mass and SUSY particles are so critical to the theory as they are the last remaining "unknowns" of the theory.

So again we come to my point: nothing that is being done at CERN will prove or disprove String theory because the energy levels at which String theory becomes testable is currently out of reach. CERN is currently focusing on making the SM stronger by finding Higgs and SUSYs and is not concerned with Strings or Gravitons (for now).

(PS: your gas law analogy fails for "k" is a direct measure of the amount of energy per temperature change and thus is not devoid of physical meaning nor is it up to scientists to "tweak". It is, like the other constants, experimentally determined)


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