Tuesday 28th April, two talks, starting 5:30 pm and 7:00 pm in the Slade Lecture Theatre, School of Physics, University of Sydney
“How to get beyond the Standard Model” The Standard Model of particle physics --- describing the fundamental constituents of
matter, and their interactions --- has been extraordinarily successful. Over decades it has
passed every test set for it, and even now there are only a handful of measurements in
conflict with its predictions: few-sigma effects of the kind that come and go, and are
inevitable when many measurements are made. Any one of them might be the first sign of
something new ... or they might all evaporate, as other presumed failings have done in the
past. And yet we know that the Standard Model is incomplete. The mathematics itself tells
us that something else must be going on, but doesn't determine what that "something" is.
Experiment has to find a way. There are three broad strategies being pursued at accelerator
laboratories around the world, to find that way forward. One can increase the energy of the
particles in colliding beams, giving access to shorter distances, and more massive
fundamental particles: this is the approach of the Large Hadron Collider at CERN. One can
make the beams more intense ("more amps" rather than "more volts") as at labs in
California and Japan, using precision measurements to probe for new phenomena hiding in
the fine print of the theory. Or one can use neutrinos, whose very difficulty --- they interact
only by the weak nuclear force --- makes them sensitive to certain kinds of new physics. In
this talk I will review these three approaches, with examples of how they have worked in
the past, and of the experiments that are currently bringing them to life. Until it happens,
we can't know which approach (all of them with Australian involvement) will be the one to
finally break the Standard Model, and show the new physics beyond it.
Details + biography
“The Acoustics of Musical Wind Instruments – and of Musicians”Wind instruments have a valve or control oscillator (reed, player's lips, air jet)
coupled to two acoustic waveguides: the bore of the instrument (downstream) and the
player’s vocal tract (upstream). This talk introduces some of the interesting effects,
including multiphonics or chords produced in woodwinds by superposition of
standing waves, and the interactions between the resonances of the bore and the vocal
tract. Our lab has developed techniques for measuring the acoustical properties of
musical instruments, especially the acoustical impedance spectrum, (the ratio of
acoustic pressure to acoustic flow, in nice analogy with electrical impedance). We
have used this to provide databases for wind instruments that allow the development
of physical models precise enough to make predictions and analyses useful to makers
and players. We have also used it to measure the impedance spectrum of the vocal
tract, while it is in use for speech, singing or playing. In this talk we’ll see how the
player’s vocal tract is involved in performance on wind instruments, including the
didjeridu, where the tract has a spectacular influence on timbre, and on some reed
instruments, where it can have a strong influence on pitch.
Details + biography |