Seven Brief Lessons on Physics Read Online Free

generated by particles that physicists, with little sense of the ridiculous, call “gluons.”
    Electrons, quarks, photons, and gluons are the components of everything that sways in the space around us. They are the “elementary particles” studied in particle physics. To these particles a few others are added, such as the neutrinos, which swarm throughout the universe but have little interaction with us, and the “Higgs bosons,” recently detected in Geneva in CERN’s Large Hadron Collider. But there are not many of these, fewer than ten types, in fact. A handful of elementary ingredients that act like bricks in a gigantic Lego set, and with which the entire material reality surrounding us is constructed.
    The nature of these particles, and the way they move, is described by quantum mechanics. These particles do not have a pebble-like reality but are rather the “quanta” of corresponding fields, just as photons are the “quanta” of the electromagnetic field. They are elementary excitations of a moving substratum similar to the field of Faraday and Maxwell. Minuscule moving wavelets. They disappear and reappear according to the strange laws of quantum mechanics, where everything that exists isnever stable and is nothing but a jump from one interaction to another.
    Even if we observe a small, empty region of space in which there are no atoms, we still detect a minute swarming of these particles. There is no such thing as a real void, one that is completely empty. Just as the calmest sea looked at closely sways and trembles, however slightly, so the fields that form the world are subject to minute fluctuations, and it is possible to imagine its basic particles having brief and ephemeral existences, continually created and destroyed by these movements.
    This is the world described by quantum mechanics and particle theory. We have arrived very far from the mechanical world of Newton, where minute, cold stones eternally wandered on long, precise trajectories in geometrically immutable space. Quantum mechanics and experiments with particles have taught us that the world is a continuous, restless swarming of things, a continuous coming to light and disappearance of ephemeral entities. A set of vibrations, as in the switched-on hippie world of the 1960s. A world of happenings, not of things.
    The details of particle theory were built gradually in the 1950s, 1960s, and 1970s by some of the century’s greatest physicists, such as Richard Feynman andGell-Mann. This work of construction led to an intricate theory, based on quantum mechanics and bearing the not very romantic title of “the Standard Model of elementary particles.” The Standard Model was finalized in the 1970s, after a long series of experiments that confirmed all predictions. Its final confirmation occurred in 2013 with the discovery of the Higgs boson.
    But despite the long series of successful experiments, the Standard Model has never been taken entirely seriously by physicists. It’s a theory that looks, at least at first sight, piecemeal and patched together. It’s made up of various pieces and equations assembled without clear order. A certain number of fields (but why
these
, exactly?) interacting among themselves with certain forces (but why
these
forces?) each determined by certain constants (but why precisely
these
values?) showing certain symmetries (but again, why
these
?). We’re far from the simplicity of the equations of general relativity and of quantum mechanics.
    The very way in which the equations of the Standard Model make predictions about the world is also absurdly convoluted. Used directly, these equations lead to nonsensical predictions where each calculated quantity turns out to be infinitely large. To get meaningful results, it is necessary to imagine that the parameters entering into them are themselves infinitely large, in order to counterbalance the absurd results and make them reasonable. This convoluted and baroque procedure