Teaching physics to a dragon

Following on from this and this, I’ve finished the two Simon Singh books I was reading and am now about half way through my advance copy of Chad Orzel’s “How To Teach Physics To Your Dog“.

The following comments focus more on negatives than on positives, which is purely in the nature of comments and nothing to do with the nature of the book. Things that are explained perfectly well tend to be invisible, and there’s only so much I can say about them. It’s the things that leave me puzzled that lead me to thinking, and to having something to say. So this isn’t intended as anything remotely approaching a balanced review, quite aside from the fact that I’ve only read half the book.

  • The bit on decoherence is great. It explains decoherence far better than anything I’ve read before and is my favourite bit so far.
  • The dog says “that’s weird” a lot. I can’t argue with this, but it seemed somewhat at variance with the way the book was promoted, from which I expected the dog to accept quantum weirdness more readily. This isn’t a complaint, just an observation.
  • I don’t get what’s so weird about the Quantum Eraser, other than things that are already weird in simpler double-slit experiments in any case. Once you’ve accepted that a photon can interfere with itself, are the results of the quantum eraser experiment not simply what you’d expect? Even in classical physics, surely, light only interferes with light that’s similarly polarised.
  • I’ve just read the chapter on the Quantum Zeno Effect, and I have some problems with it, primarily with the bit that begins “Here’s a simplified version of this quantum interrogation experiment“. The experiment described strikes me as too simplified (as in probably a complete fiction). It involves mirrors, but I found it unclear whether it was saying you can actually get a QZ effect using mirrors or whether they’re every bit as analogical as the bunny. I strongly suspect the latter, because the QZ effect obviously won’t work with discrete events such as reflecting off or passing through an imperfect mirror if the probability of what happens at each encounter with the mirror is independent, and no explanation is provided of why that might not be so. I can imagine a scenario in which they’re not independent, for example by supposing each time the photon hits the mirror it damages the mirror slightly, making it more likely that the next one will pass through, and then whenever the QZ effect is activated the mirror is repaired (by the magic bunny?), but the book doesn’t take the analogy that far and as I’ve said is unclear about the extent to which it’s an analogy at all.
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One Response to “Teaching physics to a dragon”

  1. Chad Orzel Says:

    Here’s a manual TrackBack to a post where I (try to) answer the questions about the quantum eraser and quantum Zeno effect. I hope those help, and I hope you enjoy the rest of the book.


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