this post was submitted on 21 Apr 2024
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Big brain tech dude got yet another clueless take over at HackerNews etc? Here's the place to vent. Orange site, VC foolishness, all welcome.
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A lesswrong attempts to explain physics using Information Theory!. This irritates me.
No, you can't, because you're still presuming that gases do expand, i.e., that merely connecting two containers is enough to mix their contents. Otherwise, you're saying that if you fill one bottle with orange juice and another with vodka, and then forget which is which, you've made a screwdriver.
Then it gets weird and confused, talking about a box divided in two parts, with green particles on one side and pink ones on the other.
Forgetting where things are doesn't give you psychoflexitive powers!
And from the comments:
No. If you don't incorporate quantum mechanics (or at the very least take some results of quantum mechanics as valid), you will get statistical mechanics very wrong rather quickly. Your results for the thermal properties of gases will get worse the more you calculate. You'll convince yourself that magnets are impossible. Etc.
For all that Yud has been praising the Feynman books ever since HPMOR at least, he doesn't seem to have inspired his fans to actually read the Lectures on Physics.
This is how The Sequences teaches you to think. Construct a thought experiment and use your feelings about how things "should" work to come to a conclusion.
Now i wonder how many of ea forums regulars are homeschooled
What the heck did I just read because it appeared to be a proof that hourglasses can't possibly work if you look away from them for a moment.
Hourglasses work by inverse Weeping Angels rules, doncha know?
I should also have mentioned the part where they say that the entropy of the "uniform distribution over (0,x)" is the base-2 logarithm of x. This is, of course, a negative number for any x they care about (0 < x < 1), and more strongly negative the smaller x becomes.
Argh. These people just don't know any math and never call each other out for not knowing any math, and now I have to read MIT OpenCourseWare to scrub the feeling out of my brain.
I think there is in fact a notion of continuous entropy where that is actually true, and it does appear to be used in statistical mechanics (but I am not a physicist). But there are clearly a lot of technical details which have been scrubbed away by the LW treatment.
The fact that the naive continuous version of the Shannon entropy (just replacing the sum with an integral) can go negative is one reason why statistical physicists will tell you not to do that. Or, more precisely: That's a trick which only works when patched up by an idea imported from quantum mechanics.
yea i did try to read the lecture notes and got reminded very fast why i don't try to read physics writing lol
This sounds like the setup to a Greg Egan book.
Object permanence is calling…
Another problem: They claim to derive the idea of pressure by having proved that the number density (particles per volume) is the same on both sides of the partition. But this is only the right condition for equilibrium if the temperatures are equal on both sides. This is what happens when you don't check your revolutionary new method against the ideal gas law....
A related issue that I doubt they've ever thought through: In statistical mechanics, the probability densities are defined on phase space, meaning that they're functions not just of position, but also momentum. They wouldn't be the first to get confused about this, helped along by oversimplified illustrations of "high entropy" and "low entropy" states that ignore the momentum part. But when you're reinventing a subject, it helps to avoid students' misconceptions about it.
Well it’s one thing to see someone tie red strings on a corkboard to try explain gases, and it’s another to see people in the comments buy into the idea. But then again, we are in the presence of acausal roboticists