[SEQ RERUN] Identity Isn’t In Specific Atoms
Today’s post, Identity Isn’t In Specific Atoms was originally published on 19 April 2008. A summary (taken from the LW wiki):
As a consequence of quantum theory, we can see that the concept of swapping out all the atoms in you with “different” atoms is physical nonsense. It’s not something that corresponds to anything that could ever be done, even in principle, because the concept is so confused. You are still you, no matter “which” atoms you are made of.
Discuss the post here (rather than in the comments to the original post).
This post is part of the Rerunning the Sequences series, where we’ll be going through Eliezer Yudkowsky’s old posts in order so that people who are interested can (re-)read and discuss them. The previous post was No Individual Particles, and you can use the sequence_reruns tag or rss feed to follow the rest of the series.
Sequence reruns are a community-driven effort. You can participate by re-reading the sequence post, discussing it here, posting the next day’s sequence reruns post, or summarizing forthcoming articles on the wiki. Go here for more details, or to have meta discussions about the Rerunning the Sequences series.
I have a problem with one point made in Quantum Explanations. The article seems to imply that there is something wrong with teaching modern physics in order of its discovery. While I understand the point that Eliezer is making, I disagree with it because there is a very important advantage to teaching physics in this order. Compared to armchair rationalists, physics students need a much more intimate understanding of physical theories and how they apply to experiments. Students have to actually look at the experiments and make predictions according to different theories, then look at the results of the experiment and see which theory is correct. It’s not enough to profess that a particle is a probability amplitude, a physicist needs to point to specific experiments that show how it can’t be a particle or a wave exactly. That’s why physics is taught how it is. When students learn relativity they always start with Michelson-Morley, because they need to learn what classical physics predicts and why it is wrong. This is confusing, but it helps teach them how to do science.
After reading this sequence I felt like I could say one or two things about QM, but I didn’t actually understand anything. I couldn’t look at a particle in a box and predict where it could be. I couldn’t explain x-ray diffraction, double-slit experiments, blackbody radiation, or why the heck we find certain cosmic rays at the surface of our planet where they shouldn’t have been according to classical physics. The whole sequence seems totally disconnected from experiment, which is a major fault IMO.
I’m a quantum physics student by the way.
The point of the quantum physics sequence is not to teach quantum physics, or else it would be a textbook requiring difficult math that most people can’t understand without an unreasonable amount of study. In terms of the science, it is there to teach you how to make sense of quantum mechanics once you’ve learned the difficult math behind it, because the way it’s taught in universities makes it extremely unlikely the truth will bubble up in a given person’s head on its own.
But that’s still not the point of the quantum physics sequence. In fact, there are many reasons why Eliezer wrote it, and most of them have little to do with quantum mechanics and are really about rationality. That’s why instead of explaining quantum mechanics in detail, it explains exactly enough to allow readers to see for themselves the explanation that makes sense and how scientists get it wrong.
Going over famous experiments does not require difficult math. For instance, the photoelectric effect can be entirely summed up by KE = hf—w. It’s easy math, but it has important results.
What “truth” are you talking about here?
What’s wrong with teaching about the experiments after giving Eliezer’s non-confusing explanation?
Nothing except that this may take enough time you may have to cut mechanical things, so you’d probably want to have them done concurrently.
Are people downvoting that because you think doing things at the same time won’t actually save time? But it will! Philosophy takes time to soak in. Feed it to them in bite-sized chunks while they’re learning the math, and they’ll get it; but try to do it all at once in the beginning—make it a blocking process—and you can’t wait for the soaking-in.