The new Quantum Mechanics (a.k.a. QM) idea we introduced last time is that energy comes in lumps – quanta.  Another name for a quantum is a “wavicle”, a made-up word I like to use because it conveys both important parts of its behaviour: particle-like (“corpuscular”) and wave-like. Which behaviour you see depends on how you probe the quantum and at what energy. In the case of photons, energy E is proportional to frequency f; the constant of proportionality is known as Planck’s constant and denoted h (which is very small in SI units).

Two hallmark experiments helped convince physicists that all subatomic particles (including photons, electrons, etc.) display wavelike properties. These were Young’s double-slit experiment, which showed interference, and the Davisson-Germer experiment, which showed diffraction. These two behaviours (example pictures are in the notes) are characteristic of physical systems of waves, as anyone who has played with water in the bathtub/swimming pool will know. Diffraction is bending of waves around a small obstacle or spreading out of waves from a small opening. It can occur because waves are extended objects, not residing just at a one point in space. Interference patterns arise when (at least) two wave sources are present, and happen when waves from the different sources can either pile up together, adding to make a bigger wave amplitude, or cancel each other out. The pretty pattern is what you see in the region where waves from the two (or more) sources overlap.

In Young’s double-slit experiment, he set up a first screen with a teeny hole (“slit”) in it, to let sunlight in. His second screen, behind the first, had two teeny holes in it, equidistant from the slit in the first screen. Finally, a detector was placed behind the second screen. Young was looking to see what pattern eventuated. If photons (the particles used in this experiment) were corpuscular – i.e. like classical bullets – then they would have piled up on the screen in two peaks at the exact locations of the two slits. What Young saw was instead an interference pattern with alternating light and dark fringes! These arise at places where waves either add or cancel out, depending on the difference in distance between the two slits and the detector position, giving a light or dark fringe accordingly.

The Davisson-Germer experiment had a very different nature. Electrons from a heated filament were accelerated via an electric voltage, and allowed to strike a target made of Nickel metal.  If the impinging electrons were classical bullets, they would ricochet off the wall in the style of a tennis ball reflecting off a concrete wall. The angle of reflection would be the same as the incident angle, measured from the perpendicular to the target.  But this is not what Davisson and Germer saw at Bell Labs in the 1920s.  They actually saw a series of peaks, at a variety of angles, not just the classical reflection angle! This is diffraction and could only arise from wavelike behaviour of the electrons.

In 1924, Louis de Broglie presented a very bold hypothesis for the wavelength of any quantum to his PhD committee. They wanted to fail him, because he had almost no evidence to back up his contention. It was later realized de Broglie was amazingly prescient – his formula turned out to be correct! It says that the quantum wavelength λ is given by λ=h/p, where p is the momentum and h is Planck’s constant. So for a wavicle with higher momentum, its wavelength is shorter. Or a long wavelength results from low momentum. Quantum wavelengths tend to be noticeable only for subatomic wavicles because h is so small in SI units.

Physicists built up firm evidence for the wavelike behaviour of electrons and other important subatomic animals in the 1920s, 30s, and beyond. One special thing to notice is the requirement of having an integer number of wiggles of an electron wave upon making a full revolution around the nucleus. This is a necessary consistency condition to ensure that the wave matches back up onto itself properly. (Otherwise, it would end up cancelling itself out!) This need to fit an integer number of wiggles around a finite sized atom is the fundamental reason why you see quantum numbers. These are discussed in chemistry textbooks as the principal quantum number n and the two angular momentum quantum numbers m and l. There are 3 because there are 3 dimensions of space. (The shapes of various possible wavefunctions for hydrogen are illustrated in a figure.)

Physicists have found it very useful to encode the wavelike behaviour of quanta in something called the wavefunction Ψ. This little chap, who is different for each particle with particular mass and spin, obeys a differential equation involving both changes in time and variations over space. In the case of massive quanta in the non-relativistic regime, the equation is called the Schrodinger equation, which essentially expresses the story of the energy budget for the system.

If relativity is added to QM, the result is known as QFT or Quantum Field Theory. In QFT, the object Ψ becomes a quantum field, a thingie capable of representing the quantum physics of (say) multiple electrons and their antiparticles at the same time. The equation governing the electron-positron field is known as the Dirac equation. QFT is a very powerful apparatus, and learning it is a graduate-level endeavour. It is a quintessential tool for any researcher studying subatomic physics, experimentalists and theorists alike.

One thing physicists discovered while studying wavefunctions is that the Schrodinger (or Dirac, etc.) equation computes how Ψ evolves into the future and across space. BUT what Ψ gives physicists is only the probability for detecting the particle in question! That probability is proportional to |Ψ|² and has to add up to 100%, counting all possible outcomes. This might not look like much conceptually, until you realize that this quantum mechanics is inherently probabilistic – what you actually end up detecting is purely up to random chance! Quantum mechanics breaks classical determinism – the older Newtonian-era idea of the universe as a giant clockwork machine goes out the window! All you can predict precisely as a physicist is the probability; the actuality happens in a purely random way. Albert Einstein found this concept extremely disturbing, and he never accepted it – he famously said “God does not play dice with the universe!”. Stephen Hawking, decades later, came up with a very pithy rejoinder – “It was Einstein who was confused, not the quantum theory!”. This amusing anecdote reminds us that physics is beholden to experiment: what we need to explain theoretically is what is, not what we would like necessarily.

The most famous statement of the physical uncertainty inherent in QM is the Heisenberg Uncertainty Principle. It originates in the wavelike nature of quanta, which “fuzzes out” the physics compared to our classical expectations. Unfortunately the HUP is often misquoted, especially by social scientists who want to co-opt physics terms to make themselves sound more authoritative. (Instead, they just make themselves look foolish, through their dire lack of science literacy!). What the HUP actually says is this: specific pairs of variables are affected by a minimum uncertainty – if you get too precise measuring one variable in the pair (e.g. momentum) you lose precision in measuring the other (e.g. position) and vice versa. Mathematically this is expressed as ΔpΔx ≥ h . Energy and time are another pair of physical observables affected by Heisenberg uncertainty. This is not fundamentally a measurement disruption problem, it’s  more that a quantum doesn’t even have a precise position and momentum at any given time. Physics is fuzzier in the microscopic realm than we are used to in our more macroscopic human world.

Here is the narrated slideshow as a mp4 video, as an aac audio file, and as a PDF file of slides.

Classical physicists thought they had physics pretty much sussed out by the late 1800s. Dynamics of classical systems – even including electromagnetism – was well understood in a wide range of contexts, but for just a few “tiny” niggling details. However, these were details which turned out, upon deeper investigation, to be huge gaping holes in our understanding which would necessitate entire new branches of physics and mathematics to be developed! Many practicing research scientists will recognize this situation – phenomena in nature that are interesting enough to study nowadays are likely to be subtler than we tend to guess at first glance.

Colour, as we see it, is related to the wavelength(s) of light that are reflected from objects in our field of view. Only red light is reflected from a red apple, for instance – not green or blue. One interesting question physicists from a century ago asked was: at a given temperature, how does electromagnetic radiation behave when interacting with a thermal system? A useful prototype of such a system is called a Blackbody, which is defined as something that is a perfect absorber (/emitter) of EM radiation and sits at a particular temperature T.

Physicists studying thermodynamics (which we introduced in Ep.6) discovered a very useful fact: that thermal systems have an average energy – per available independent mode of motion – that depends only on the temperature. This is quite a neat result and was dubbed the Equipartition Theorem. Today we recognize that polyatomic molecules have 3 types of independent modes of possible motions: translational (3 directions of linear motion), rotational (3)  and vibrational (the rest). What about photons? Those are different kinds of animals in principle, because (unlike atoms) photons have no rest mass. This makes their physics unique.

Photons behaving according to Maxwell’s equations of classical EM can have any energy that you can imagine in your mind. Putting together that Maxwellian knowledge with classic thermodynamics leads, unfortunately, to a very deeply puzzling conclusion. The puzzle can be appreciated even without math by focusing on the nub of the problem: photons in a box can exist in either the fundamental mode or any one of an infinite possible number of overtones! This is a lot like the multitude of different possible notes a musician can play on a stringed or wind instrument.

There is indeed an entire infinity’s worth of possible independent modes of motion for photons – their only constraint is that they behave like standing waves, because the EM waves aren’t allowed to leak outside the box into which we said we put this system in the first place. All we have to do to satisfy the constraint is ensure that an integer number of half-wavelengths fits into the box! And, because there is an infinite number of possible EM modes in a box, the average energy of blackbody radiation is, classically, infinite. This is called the Ultraviolet Catastrophe and is obviously in direct conflict with experiment. Our Sun, for instance, an approximate blackbody at a temperature of about 6000 Kelvin,  does not vaporize us into a puff of smoke!

So how does quantum physics address this problem? By recognizing that energy isn’t actually continuously variable, but in Nature it occurs in lumps known as quanta. A quantum or lump of EM radiation is known as a photon. Realizing that energy comes in quantized, discrete units, is enough to render the effective number of modes finite and make the sum in the average total energy well behaved. What’s even more impressive is that this single change in assumptions explains both blackbody radiation and much more besides. Along the way, we mention how hotter blackbodies radiate at shorter wavelengths. In other words, the hotter, the bluer.

To wrap up this first part of a two-part introduction to Quantum Mechanics, we talk about the Photoelectric Effect. This is a phenomenon that puzzled classical physicists of the day but was understood with an immense flash of clarity by Einstein. He recognized the reason why a UV light shone on a metal would produce an electric current, whereas longer-wavelength EM radiation would not produce any measurable current – regardless of the intensity with which it was aimed at the metal! That seemed very counterintuitive for a classical physicist.

Again, the only piece of physics really needed to explain this is the quantization idea. Not only do atomic energy levels for electrons come only in very specific energies, dictated by the Pauli Exclusion Principle for fermions and by quantum physics, but so do photon energies! Energy comes only in quantized packets or lumps. If your incoming photon doesn’t have a high enough frequency, it can’t clear the energetic hurdle required to kick an electron out to a higher energy level or even jump ship from the atom entirely (get ionized).

That’s why a current didn’t get generated when longer wavelength EM fields were used, as compared to the case with the UV light. Clearing only 90% of the height of the energy hurdle (for instance) just doesn’t cut the mustard. You don’t win an Olympic medal by beating your competitor 90% wholeheartedly. You either clear the bar for recognition, or you don’t. Same for photons kicking electrons out of metals. 

Here is the narrated slideshow (or just the audio) of my slides for Episode 7.

General Relativity is a nonlinear theory, one in which the response of a system is not  proportional to the stimulus applied. (Climate is another good example of a highly nonlinear system.) This nonlinearity is important to GR’s ability to have black hole spacetimes in it, as physically allowed solutions of the Einstein Equations. After mentioning this tidbit, we describe an important property of black holes – the fact that they have no “hair”. There’s just the black hole, no frills or bling added. Observers outside of the event horizon can discern at most a measly three properties of the black hole: mass M, angular momentum J and (in the case of theory black holes rather than astrophysical ones) electromagnetic charge Q. No other information about what lies behind the horizon can leak out.

… Or can it?

Stephen Hawking’s famous insight was that quantum mechanics – the physics of the microscopic world – can indeed permit radiation of particles (massless or massive) from black hole horizons. Although, for astrophysical black holes the ensuing temperature of the radiation is extremely cold: significantly colder than the temperature of about 3 Kelvin of the Cosmic Microwave Background! The discovery of Hawking radiation totally rocked the world of researchers working on black holes, leading to breakthroughs in understanding the thermal physics of black holes and matter interacting with them. Interestingly, the temperature of smaller black holes is more fierce, raising the interesting question of what happens at the endpoint of runaway evaporation of small black holes. More on that later in the course.

The essence of Hawking radiation is the phenomenon of virtual pair production, which occurs in Nature even in the so-called “vacuum” where there are no [real] particles. I refer to pair production as “pair popping”, because the virtual particle-antiparticle pair pops into existence only for an extremely short time allowed by the Heisenberg Uncertainty Principle before it pops back out of existence, disappearing into the vacuum. The message here is that energy conservation can be violated in quantum processes, BUT ONLY if you do it so fast that quantum uncertainty lets you get away with the crime because no-one notices you’ve committed it.

Pair popping with both particle and antiparticle on the same side of the horizon is not the interesting phenomenon in the context of black holes. The interesting phenomenon is when a pair pops into existence straddling the horizon, and one pair is lucky enough to have sufficient momentum/energy to escape while its partner falls into the centre of the black hole. We show how, using the principle of energy conservation over macroscopic timescales, the black hole loses a little bit of its mass in a Hawking process.This is called Hawking evaporation.

The discovery of the Hawking temperature motivated theoretical physicists to study, armed with Gedankenexperiments, the thermodynamics of black holes. We introduce the thermodynamic concept of entropy, a measure of disorganization of a system (or, equivalently,  wasted heat in a thermal process). We explain in a bit of detail why it is physically useful to know about entropy in thermal systems. We explain that black holes, by virtue of their incredibly strong gravity in their densest parts, have a humongous entropy that is proportional to the area of their event horizon in units of the Planck scale, the tiniest imaginable distance at about 10^-35m. This black hole entropy somehow encodes the different possible ways that the black hole of given M, J, Q could have been formed from gravitational collapse of matter with mass, spin and force charges.

We finish with a discussion of the Black Hole Information Problem – which is caused by the fact that even outgoing Hawking radiation from a black hole horizon only knows those three data: M, J, Q. Even the Hawking radiation, the only thing apparently emitted by black holes, cannot carry sufficient information to recover data from matter thrown into black holes. We explicitly explain why this behaviour is very unlike that of a lump of coal, which is governed by the sensible rules of quantum electromagnetism, known as “QED” (Quantum ElectroDynamics). The BH Information Problem, which is still an extremely active area of forefront theoretical research (taking up a good fraction of my research time, for instance), poses yet another deep difficulty for Einstein’s theory of General Relativity. GR, as we explain, is only a classical theory of gravity. For an understanding of a quantum theory of gravity, and a deeper understanding of black hole singularities and horizons, we have to dig deeper. This is part of the motivation for the invention of string theory.

Here is a PDF file of my slides for this episode 6, and this is the narrated slideshow.

Our focus in Ep. 5, this episode, is black holes. We start by discussing the concept of escape velocity for satellites in Earth orbit, showing that the outcome of a launch depends on how much kinetic energy (energy of motion) the satellite had upon launch. We also recall that satellites that do end up orbiting gravitating bodies do so in elliptical orbits, in the Newtonian approximation. This helps explain why bodies launched with insufficient velocity come back to earth, like a thrown baseball. On the other hand, bodies launched with too much velocity get flung into outer space, having kinetic energy left over after they’ve climbed up and out of the earth’s gravitational well. Bodies launched with Goldilocks ‘just right’ speed are the ones that end up orbiting in ellipses. Along the way, we bust the myth that astronauts on the space shuttle don’t feel gravity – in fact they do, they’re just freefalling like the shuttle is as they orbit Earth. What they don’t feel is g-forces (an acceleration concept distinct from gravity itself).

We use the concepts of kinetic energy and gravitational potential energy to motivate a straightforward formula relating escape velocity to the mass of the big gravitating body, and to the distance from the centre of the body on launch. The closer in the satellite starts, the harder it is to escape the clutches of the big body’s gravity. The more massive that body, the harder it is to escape. We explain how the escape speed can even rise to the speed of light if you start out close enough to the centre of a gravitating body; this occurs at a radius called the Schwarzschild radius. This motivates the definition of a black hole as an object so dense it is physically contained within its own Schwarzschild radius. Another way of saying the same thing is that a black hole is a spacetime with such strong gravity that not even light can escape its clutches, if it falls in close enough to get caught by the black hole.

We next discuss the important features of the anatomy of black holes – horizons and singularities. The event horizon is defined as the surface of no return: if you cross it, you are fated to be drawn into the interior of the black hole and never come out again, ever. Physics behind the horizon may be interesting, but physicists there cannot communicate any of their results to the outside world because even photons are trapped inside the horizon! The singularity is a place, at the centre of a black hole, where the curvature of spacetime becomes formally infinite. That is a very nasty place indeed, because tidal forces – gravitational forces that stretch/squeeze perpendicular directions of a body (and which cause our ocean tides, incidentally) – are infinite at the singularity. So anything falling into the black hole singularity (everyone does, if they crossed the Schwarzschild radius) will be spaghettified in an untimely death. We mention en passant the deep problem of Einstein’s equations predicting curvature singularities; this motivates the need to develop “Gravity 3.0″: quantum gravity.

We next talk about how astronomers infer the existence of black holes, which are formed upon gravitational collapse when dead stars have run out of gas. The essence of their technique is to observe electromagnetic radiation emitted by particles in the accretion disk that forms around around the central black hole from gravitational attraction of nearby gas and dust, particles which can be heated to millions of degrees by friction in that disk. Redshift/blueshift of EM radiation is again the key idea. We also mention other clever methods used by astrophysicists and astronomers as well.

With the aid of a pretty poster from the Chandra web site at Harvard, we expand a little on stellar evolution for different kinds of stars. For instance, our Sun, after going through a red giant stage, will end up as a white dwarf star held up by electron Fermi degeneracy pressure (a concept we mentioned in episode 2 when introducing fermions). Bigger stars instead end up, after a spectacular supernova explosion, as neutron stars – which are held up by neutron Fermi degeneracy pressure. Even bigger ones, stars that started off at least ~5 or so times heavier than our Sun, eventually collapse in on themselves and form a black hole. In those cases, the stars are so heavy that no other force – not even electromagnetism, nor the weak nuclear force, nor the strong nuclear force – is able to prevent gravitational collapse!

There is a second interesting population of black holes in the universe. Black holes have also been discovered at the centre of most galaxies, dubbed supermassive black holes, with masses in the range of millions to a billion or so solar masses. Our own Milky Way galaxy has one of these. Supermassive black holes are important drivers of galactic evolution, and constitute a very active area of research in astrophysics. We finish with a Chandra picture of two active galaxies colliding, which includes a merger of supermassive black holes.

Here is a PDF of my slides from today. This is the narrated slideshow movie.

We kick off Episode 4 by describing how knowledge of Newton’s three laws of motion and Newton’s law of universal inverse-square gravitation aids astronomers in discovering planets orbiting other stars. The most important physics points in this story are (1) stellar recoil (like with a gun firing a bullet) and (2) blueshift/redshift, which is similar in some ways to the Doppler effect for sound, wherein frequencies are upshifted for sources approaching us but downshifted for sources moving away. This blue/redshift effect for light gets contributions from time dilation and from the motion of the source, and does not depend on any medium (EM waves travel just fine in vacuum). By focusing on spectral lines for emissions/absorption from gases like hydrogen, we show how astronomers deduce the planet/star mass ratio from observations of stellar radial velocity wobbles.

We then segue into a discussion of fundamental properties of photons. Photons are quanta of the EM field, i.e., indivisible packets of electromagnetic energy. We discuss how photon frequency f is related to photon energy E by the formula E=hf, where h is Planck’s constant. We display the entire EM spectrum of frequencies (or equivalently, wavelengths) – from gamma rays through X-rays and ultraviolet to the visible, infrared, microwave and radio bands.  We also explain the true relativistic relationship between energy, momentum, mass and the speed of light as we build up a conceptual outline of the ideas and thought processes that led Einstein to his famous theory of General Relativity. We emphasize how important Special Relativity was to the development of GR.

We also highlight the importance of Maxwell’s Equations, a beautiful synthesis of electromagnetic phenomena involving charges, currents, and electric and magnetic fields. We describe how Maxwell unified electricity and magnetism into one theoretical whole – an umbrella set of concepts that covers all electromagnetic phenomena. For art’s sake, we show off the equations.   We next emphasize the importance also of the Equivalence Principle, an idea that acceleration due to gravity is indistinguishable from acceleration from an on-board rocket. We finish our lead-up to GR with a description of Einstein’s new concept of spacetime, as a fabric warped by energy/momentum in a causal way, with gravitational disturbances moving at the speed of light. Particles just move the most natural way they can in this context, leading to curved paths like planetary orbits.

This sets the stage for our next episode (#5) developing the physics of black holes.  I hope you enjoy, and stay tuned!

Here is a PDF file of all my slides from Episode 4.

Newton’s theory of gravity is very powerful, with the ability to explain observations like Kepler’s Laws of planetary motion (like the fact that planets move in elliptical orbits, and that each orbit sweeps out equal area in equal times). One weakness of Newton’s gravity theory, however, is that it assumes the speed of transmission of gravity is infinite. This gives rise to nasty causality problems, which is part of what drove Einstein to refine Newton’s theory of gravity by formulating Relativity. Newton’s theory also predicts that light is unaffected by gravity, which turns out to be experimentally incorrect.

Einstein’s fundamental insight was that the speed of light is invariant – the same in all frames of reference. This deceptively simple looking proposition is amazingly deep, in that it forces us to rethink our conventional, low-speed-based, intuition about how velocities should add and about how every observer should measure the same time. In fact, as Einstein showed theoretically and decades of experiments have shown since, time is relative (not absolute) and velocities which are a significant fraction of the speed of light do not add simply.

Next, we demonstrate how time dilation works in a very simple example. By drawing a straightforward diagram and using simple trigonometry without any  equations, we show that – because the speed of light is the same in all reference frames – clocks look like they are running slow to an observer in relative motion. We also set up and explain the famous Twin Paradox. In particular, we explain that it is the acceleration of the astronaut twin that breaks the apparent symmetry between the twins. The astronaut twin ages less quickly than the homebody.

(I even give a page of equations describing a disarmingly simple way of computing relativistic velocity addition, for those who happen to enjoy wrangling equations. This one slide can easily be skipped.)

Here is a PDF file of my slides for Episode 3.

We draw an important distinction between bosons (which have spin 0, 1, 2,…) and fermions (which have spin 1/2, 3/2, 5/2, …). At high temperatures where particles race around with a lot of average kinetic energy, bosons and fermions behave pretty much the same, but this is not true at low temperatures. The Pauli Exclusion Principle (PEP) is a crucially important property of fermions: it says that no two fermions can be in the same quantum state at the same time. In plain language, this means that fermions have elbows. This has profound consequences which we discuss.

Matter (stuff) in particle physics is composed of fermions, while force-transmitters are bosons. The electromagnetic and two nuclear forces have spin one messengers, while gravity has a spin two messenger particle. The mysterious hypothesised Higgs boson (responsible for mass of quarks, leptons and the weak bosons) has spin zero. Another important dichotomy is that between hadrons, i.e.  baryons and mesons, made of quarks and gluons, which feel the strong force, and leptons which are not affected by the colour force. Leptons, composed of electrons, muons, taus and their associated neutrinos, do feel the weak nuclear force. Every particle possessing energy feels gravity, including photons.

We discuss properties of the four different forces – gravity, electromagnetic, strong nuclear and weak nuclear – including how they differ in range and strength. In particular, we discuss which forces act on which particles. We also develop in some detail the ice skater analogy, which motivates why particle physicists can successfully model force transmission in terms of exchange of messenger particles.

We close by giving a lightning tour of Fermilab, the Fermi National Accelerator Laboratory in the USA, and the Large Hadron Collider (LHC) based at CERN near Geneva, Switzerland.

Here is a PDF file of my slides from Episode 2.

Next up is Powers of 10, a useful shorthand for referring to a very wide range of distance scales in the Universe. Some pictures from the powers0f10 web site are included, showing an artist’s impression of what we would see at distance scales ranging from the very edges of the known universe (10⁺²⁵m) all the way down to attometre scales (10^-18m), i.e. a billionth of a billionth of a metre.

We segue into a discussion of the structure of matter, talking about atoms, nuclei and electrons. Going beyond what is normally mentioned in science courses in school, we discuss what is inside protons and neutrons: quarks and gluons. I finish up with an introduction to the strong nuclear force, which is responsible for binding atomic nuclei together stably.

Here is a PDF file with all the slides from Episode 1.

(Note: the recording sounds like it might have ended prematurely, and it did -  but only by a couple of seconds. You didn’t miss anything.)

Amanda Peet

Hi! My name is Amanda Peet, the physicist (not the Hollywood actress). I’m a tenured Associate Professor of Physics at the University of Toronto; my professional awards include a Radcliffe Fellowship at Harvard University and an Alfred P. Sloan Foundation Research Fellowship. I’m 41, and have been giving invited physics outreach talks for a couple of decades by now. I consistently get enough speaking invitations that I have to routinely turn down every year that… it’s time for a podcast.

I’d like to thank Leo Laporte for inspiring me to start podcasting, and for his generosity and general awesomeness in explaining technology, live, online. I’d also like to acknowledge the community of TWiT Army IRC buddies for encouraging me to do this (i.e., jump off a cliff!) and for much technical advice. I’m grateful to each of you.

As you’ll quickly notice if you click to watch, I’m no video/audio editor: my expertise is instead in physics research, education and service. So my episodes (at least the first several) are just going to be simple narrated slideshows, because that’s what I’m confident I can sustainably continue into the future. It’s probably just as well, because do I have a face for radio! Also, I apologize in advance about the inevitable typos and speakos that will have crept into the content: I record each episode in a single take. I hope that my general suckitude coefficient will be a monotonically decreasing function of time.

My first KiwiCast episode is an introductory one, in which I mention the topics I’m going to cover as I teach a two-semester restricted-enrolment first-year seminar course at the University of Toronto and produce these podcast episodes as I go along to help my students learn. My course is called Modern Physics in Perspective and it covers a wide range of modern physics concepts – what I like to call “sexy” physics.

From my course synopsis: “Ideas on the menu will include: space and time, relativity, black holes, quantum physics, particle physics, unification, big bang cosmology, extra dimensions, “branes”, and string theory. The intriguing story of these integrated phenomena unfolds over a wide distance and a long time. No prior experience with physical science will be required, but familiarity with Grade 10 mathematics will be assumed. Students from diverse academic backgrounds are warmly welcome.”