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  • Kick ass physics!

    Einstein is crying tears of joy right now in his grave.

    PARIS (AFP) – It's taken more than a century, but Einstein's celebrated formula e=mc2 has finally been corroborated, thanks to a heroic computational effort by French, German and Hungarian physicists.

    A brainpower consortium led by Laurent Lellouch of France's Centre for Theoretical Physics, using some of the world's mightiest supercomputers, have set down the calculations for estimating the mass of protons and neutrons, the particles at the nucleus of atoms.

    According to the conventional model of particle physics, protons and neutrons comprise smaller particles known as quarks, which in turn are bound by gluons.

    The odd thing is this: the mass of gluons is zero and the mass of quarks is only five percent. Where, therefore, is the missing 95 percent?

    The answer, according to the study published in the US journal Science on Thursday, comes from the energy from the movements and interactions of quarks and gluons.

    In other words, energy and mass are equivalent, as Einstein proposed in his Special Theory of Relativity in 1905.

    The e=mc2 formula shows that mass can be converted into energy, and energy can be converted into mass.

    By showing how much energy would be released if a certain amount of mass were to be converted into energy, the equation has been used many times, most famously as the inspirational basis for building atomic weapons.

    But resolving e=mc2 at the scale of sub-atomic particles -- in equations called quantum chromodynamics -- has been fiendishly difficult.

    "Until now, this has been a hypothesis," France's National Centre for Scientific Research (CNRS) said proudly in a press release.

    "It has now been corroborated for the first time."

    For those keen to know more: the computations involve "envisioning space and time as part of a four-dimensional crystal lattice, with discrete points spaced along columns and rows."
    Einstein's theory is coroborated.
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  • #2
    I did that years ago
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    • #3
      Are you saying French, German and Hungarian scientists are slow?
      Last edited by MrFun; November 21, 2008, 14:07.
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      • #4
        Only in Fizzics.
        Blah

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        • #5
          And how did they measure this energy for its mass equivalent without blowing it up? Sounds suspicious to me. Not that I doubt the theory, only this coroboration.
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          • #6
            That article is quite a misrepresentation.
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            • #7
              Re: Kick ass physics!

              Originally posted by MrFun
              Einstein is crying tears of joy right now in his grave.



              Einstein's theory is coroborated.
              I don't even know where to start on this article.

              1) E = mc^2 (technically E = sqrt(m^2c^4 + p^2c^2)) has been proven time and time again. It is one of the best-tested hypotheses in all of science.

              2) "The answer, according to the study published in the US journal Science on Thursday, comes from the energy from the movements and interactions of quarks and gluons.". Errrr. Yeah. I could have told you that. So could any undergraduate physics student.

              3) "For those keen to know more: the computations involve "envisioning space and time as part of a four-dimensional crystal lattice, with discrete points spaced along columns and rows."". Okay, so somebody did a QCD lattice computation and got a reasonable estimate of the mass of nucleons. This is not particularly exciting.

              12-17-10 Mohamed Bouazizi NEVER FORGET
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              • #8
                Lattice QCD is tough, and they get results which other methods have not been able to so far. For those interested, standard methodologies of interaction calculations do not work well because the strong coupling "constant" alpha_s increases as the scale of momentum transfer decreases, meaning that at low energies (such as at the scale of binding of the proton) the summation series (from higher and higher order Feynman diagrams, i.e. with higher and higher powers of alpha_s) stops converging. There is no clever resummation method yet known to do these calculations perturbatively. Lattice QCD performs the calculation non-perturbatively by breaking down interactions into small enough space-time segments (corresponding to high enough momentum scales) that each piece can be treated perturbatively. Not particularly clever or beautiful, but it works (sometimes).
                12-17-10 Mohamed Bouazizi NEVER FORGET
                Stadtluft Macht Frei
                Killing it is the new killing it
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                • #9
                  Why do gluons have no mass?
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                  • #10
                    I disagree with the Wikipedia entry on lattice QCD's characterization that the lattice scale "a" introduces a regularization at momentum scale 1/a.

                    "Lattice regularization" fixes a problem with computation, not a problem with the theory. Though the summation as written is not convergent, there is no proof (AFAIK) that the series COULD NOT, in principle, be resummed to converge to a reasonable answer. Normal regularizations fix problems with the theory (usually because there is new physics ABOVE the regularization scale); here we are not postulating new physics because the problems arise BELOW the "regularization" scale 1/a.
                    12-17-10 Mohamed Bouazizi NEVER FORGET
                    Stadtluft Macht Frei
                    Killing it is the new killing it
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                    • #11
                      Originally posted by Traianvs
                      Why do gluons have no mass?
                      Because they are gauge bosons of an unbroken symmetry?
                      12-17-10 Mohamed Bouazizi NEVER FORGET
                      Stadtluft Macht Frei
                      Killing it is the new killing it
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                      • #12
                        Specifically, they are the gauge bosons of the unbroken SU(3) of colour.
                        12-17-10 Mohamed Bouazizi NEVER FORGET
                        Stadtluft Macht Frei
                        Killing it is the new killing it
                        Ultima Ratio Regum

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                        • #13
                          ah like photons then
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                          • #14
                            No. Photons are the massless degree of freedom of the BROKEN SU(2)(left) X U(1) (hypercharge).
                            12-17-10 Mohamed Bouazizi NEVER FORGET
                            Stadtluft Macht Frei
                            Killing it is the new killing it
                            Ultima Ratio Regum

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                            • #15
                              This is electroweak unification. The gauge couplings of hypercharge and SU(2)(left) are not directly observed. Instead we observe the mixed coupling constants e and those from the massive gauge bosons W and Z. The mixing angle is actually fairly large sin^2(theta_weinberg) ~0.24
                              12-17-10 Mohamed Bouazizi NEVER FORGET
                              Stadtluft Macht Frei
                              Killing it is the new killing it
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