Show HN: Simulation-based high school physics course notes

Thanks, In the physics class I teach we go through the examples from the notes. Then, we follow up with real world labs and engineering projects to make it even more concrete. I might make my next project documenting the demos and labs that go with each unit.

Looks really good!

This is incredible work, well done.

The depth and breadth of topics and examples is amazing. Well done!

My only nitpick would be the formatting of some of the equations. Instead of

    $$ E = hf $$
    $$ E = (6.626 \times 10^{-34})(10^{9}) $$
    $$ E = 6.626 \times 10^{-25} \, \mathrm{J}$$

I think it would be clearer to use

    $$\begin{aligned}
      E &= hf \\
        &= (6.626 \times 10^{-34})(10^{9}) \\
        &= 6.626 \times 10^{-25} \, \mathrm{J}
    \end{aligned}$$

which is the KaTeX-recommended approach for emulating \begin{align} ... \end{align}.

I would also throw in a word or two of explanations in there, so it's not just equations, e.g., explain "Using the formula for the energy of a photon, we find: <eqns>". I guess it would end up being more work for you, but would be worth it for the benefit of students learning that it's not just about the numbers, but knowing what you're doing (like you do in the strategy sections).

On the other hand the current format of line-by-line-show-only-the-equation-steps is very practical too --- from my experience certain students prefer to see just the practical steps they have to do on the exam, rather than the blah blha blah around them, even if it can be educational.

It would be interesting to see some of the questions/examples converted into self-test quizzes. Show a few examples, then ask readers to solve some problems on their own. I know the idea is they will try to solve on their own an only reveal the solution after they've tried, but realistically speaking more likely they will click that arrow ;) So maybe just a delay to force them to try?

This is getting into the realm of the fancy, but you could maybe make the reading with a "customizable difficulty level." Beginner = info (maybe hides certain more advanced topics), all questions solved as examples. Intermediate = some questions solved as examples, but missing final steps so reader has to complete them to get the final answer. Advanced = most examples show as quiz questions reader has to solve on their own...

First and foremost - it is awesome!

Though, when I tried to share it on social media, but the title is not too descriptive ("Physics notes") and there is no cover picture.

Lots of nice content here.

I started with the QM section, and it felt like you jumped right in to the particle theory of light. I realized later that of course you have an in depth discussion of the wave theory of light, but I think a bit more explicit connection to that discussion could be helpful.

I particularly like coming back to Young’s double slit experiment, which I saw in your discussion of diffraction. To me, the most surprising illustration of the wave/particle duality of light is that single photons passing sequentially through the double slit still form a diffraction pattern. So these particles sort of ‘self-interfere’.

One other thought regarding the standing wave demo — maybe you are already familiar with this, but setting up higher order harmonics is a pretty common technique among guitar players (and other stringer instruments), where you pluck a string while touching one of the standing wave nodes. If you’re not familiar with ‘portrait of Tracy’ by Jaco Pistorius, it’s a really cool and unique example of this technique

https://m.youtube.com/watch?v=JXOnhzoC-i8

I started reading last night to try to give you some feedback, then bedtime for my kids arrived, etc.

I haven't found a way to start people into quantum mechanics that I like. All the material on states and superposition really doesn't help unless you've got a lot more math than a highschooler does. It also is a complete departure from the previous material because suddenly it's this mass of abstraction without reference to a physical system.

The best that I've found so far goes something like this:

When we talked about a ball flying through the air, we talked about its path. But our eyes can only distinguish changes that take at least a thousandth of a second. A camera takes a series of snapshots. We idealize that we can do 2000 measurements, or 4000, or any number and so in the usual passage from discrete to continuous we get the idea of a bath.

Implicit in this is that shining a light on the ball and measuring where it is has negligible effect on the ball.

But when we assume quantization, when we assume that there are photons and leptons, smallest particles and smallest units of interaction, we reach a point where we can't neglect the effect of the measurement. Any interaction that lets us measure it will disturb the system. So if we double the frame rate of our measurement, we disturb the system twice as often, so measuring it at 1000fps is not the same as measuring it as 2000fps and ignoring half of the frames. The more often we measure, the more disturbance we have, and it doesn't converge to a path anymore.

It's probably worth pausing and pointing out that a measurement here is linking what occurs from the interaction with the system we're measuring with a macroscopic, irreversible process. For example, a photomultiplier tube where a single incoming electron kicks off a cascade of more electrons, which kicks off even more in the next layer.

But if a measurement consists of this giant thing, and more measurements don't converge to a path, there's this big gap. Is there actually an underlying position of the particle outside of that measurement? It's not accessible to us, even if there is.

And at this point you go straight into Bell's inequalities to rule out hidden variables.

There's a lot of pedagogical problems with this, but I feel like it's the most promising route I know of.

Maybe I'm wrong, but whenever I look up the topic there seems to be contradictory information. Maybe the latest in QM is too new to be stable?

For ppl in the know, here is a simple (maybe) question:

I can model "spin" of a photon such that two photons added with opposite spin direction will result in a polarised profile: but I can also add two polarised photons that produce a rotating pattern.

polarisation always seemed unnatural to me - do "real" photons spin (one way, or another) and only combinations result in polarisation? Because photons are often depicted as elementary (not the result of combining multiple photons), but also polarisable..

Now they work as expected. Maybe it only occurs the first time you load the page...