Earlier this month CERN’s smashing machine switched from sending protons zinging around its ring to sending heavy lead ions at relativistic speeds. Those energetic collisions, the physicists now say, have allowed them to use the LHC’s ALICE experiment to glimpse quark-gluon plasma, the “primordial soup” present just after the Big Bang.
During this time, the Universe would have been so hot and energetic that the particles making up the elements we know today were unable to form, leaving the constituents to float “free” as a primordial soup. Quarks and gluons were only able to condense into larger particles when universal energy conditions were low enough. Hadrons (i.e. particles made from quarks; including baryons like neutrons and protons) were only allowed to form 10-6 seconds after the Big Bang. [Discovery News]
The standard model of physics got it right when it predicted where the mass of ordinary matter comes from, according to a massive new computational effort. Particle physics explains that the bulk of atoms is made up of protons and neutrons, which are themselves composed of 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 [accounts for] only five percent. Where, therefore, is the missing 95 percent? [AFP]
The answer, according to theory, is that the energy from the interactions between quarks and gluons accounts for the excess mass (because as Einstein‘s famous E=mc² equation proved, energy and mass are equivalent). Gluons are the carriers of the strong nuclear force that binds three quarks together to form one proton or neutron; these gluons are constantly popping into existence and disappearing again. The energy of these vacuum fluctuations has to be included in the total mass of the proton and neutron [New Scientist]. The new study finally crunched the numbers on how much energy is created in these fluctuations and confirmed the theory, but it took a supercomputer over a year to do so.