r-bryan

Why does a carpenter cut the end off a 10-foot board to get a required 9ft-2in, thereby wasting 8% of the input and incurring dumpster charges? Suppose the architect's design specified the cutlist, to be transmitted to the board "factory", which would cut boards to the required lengths, tagging them with RFID serial numbers indexed to the design, stacking them so the first ones to be used are on the top, and truck to the site without passing through Home Depot?

Check out this 156-page tome: https://arxiv.org/abs/2104.13478: "Geometric Deep Learning: Grids, Groups, Graphs, Geodesics, and Gauges"

The intro says that it "...serves a dual purpose: on one hand, it provides a common mathematical framework to study the most successful neural network architectures, such as CNNs, RNNs, GNNs, and Transformers. On the other hand, it gives a constructive procedure to incorporate prior physical knowledge into neural architectures and provide principled way to build future architectures yet to be invented."

Working all the way through that, besides relearning a lot of my undergrad EE math (some time in the previous century), I learned a whole new bunch of differential geometry that will help next time I open a General Relativity book for fun.

Methinks Zawinski's Law of Software Envelopment finds some empirical support here.

Oh FFS why is print-vs-debug being debated as either/or? Both can be valuable, depending on the circumstances. It's clearly both/and.

Well dang, we are not restricted to git as the only place we can put historical metadata. You know, discursive comments, for starters?

I once worked with a company that provided IM services to hyper competitive, testosterone poisoned options traders. On the first fine trading day of a January new year, our IM provider rolled out an incompatible "upgrade" to some DLL that we (our software, hence our customers) relied on, that broke our service. Our customers, ahem, let their displeasure be known.

Another developer and I were tasked with fixing it. The Customer Service manager (although one of the most conniving political-destructive assholes I have ever not-quite worked with), actually carried a crap umbrella. Instead of constantly flaming us with how many millions of dollars our outage was costing every minute, he held up that umbrella and diverted the crap. His forbearance let us focus. He discretely approached every 20 minutes, toes not quite into entering office, calmly inquiring how it was going. In just over an hour (between his visits 3 and 4), Nate and I had the diagnosis, the fix, and had rolled it out to production, to the relief of pension funds worldwide.

As much as I dislike the memory of that manager to this day, I praise his wisdom every chance I get.

Yeah, basically the oil companies pumping up fossil fuel to burn, but we get a single use of it as plastic before it goes to the incinerator.

A little stoichometry suggests that, ignoring oxygen, hydrogen, and energy input, the cited worldwide market for C2H4 would be satisfied by just about 1 gigaton of CO2. So if "we need to process gigatons of CO2 annually", that ethylene's gonna pile up.

Earth escape velocity is 11.1 km/s, which is Mach 32 at sea level. They have some more engineering to do, maybe even invent something better than carbon fibers.

"Always be yourself. Everyone else is already taken."

OK, but I'd rather prevent/cure the dementia.

I can highly recommend Epsilon (emacs-like) from lugaru.com.

Be an engineering mentor for your local high school robotics club. From personal experience, I can guarantee that you will come upon aspects of engineering where you are a rank newbie, yet wish you had even a little competence. It's exhilarating when external and internal motivations coincide to push you to develop new skills.

There is an unfortunate fallacy here. Your notion "the real world" conflates the physical world with a social milieu. The physical world is (at this scale) immutable, so of course we must conform to it and update our science-like models.

But there is no absolute requirement to conform oneself to a social milieu. A social milieu changes. It can be altered. It supports a vast number of models. And milieus overlap so densely that one can just go play somewhere else.

Disclosure: I used to be a Lisp bigot, but I got better.

This scenario is very reminiscent of the leadup to the Innovator's Dilemma. The dinosaurs grow taller and fatter seeking and thriving on the juicy foliage higher up the tree, while the scrappy little mammals claw away at its soft underbelly.

Nobody's going to fabricate semiconductors in their garage. But couldn't someone make a modest profit without first investing $2.0e10, like Intel? Or is it just that the profitability scale is such that if you had an extra $2.0e7 to invest, you're better off buying Intel stock?

I dunno. Don't we have yet to resolve where the curly braces belong, or emacs vs vi, or mac vs pc, or red sox vs yankees, or at least what materials to use for the staff bikeshed?

The author missed Symbolics Document Examiner and its partner, Concordia, dating from around 1985. Disclaimer: I led the implementation team.

As Carl Sagan might have said, "To build a platform from scratch, you must first create the universe."

I don't see why zero-growth has to be zero-sum.

If not all the "labor" inputs are eaten up by society-wide subsistence, some value will continue to accumulate, somewhere. To the degree that owners allow the workers to retain any of their "surplus value of labor," everybody's lot will continually improve.

The book _Writing on Both Sides of the Brain_ (Henriette Klauser) got me unstuck. Ignoring the left-brain/right-brain stuff, imagine that you have a creative, let it fly part and a critical editor part. Constant criticism from the editor can slow all creativity to a stop. Instead, tell the editor, "I promise you'll get your chance. For now, sit down and shut up." Then create in peace, but follow through on that promise.

Cool. Now solve it for a circular fence on the surface of a sphere. In fact, solve all four cases {exterior, interior of sphere} X {exterior, interior of fence}. Spherical trig can only make the solution(s) even more heroic, right?

Maybe it was ObjectStore (read about it on Wikipedia). Pretty clever, I thought.

That PDF document was produced by some historical interviewers, not Symbolics. Your comment roundly criticizes Symbolics for someone else's work. Only in the words it contains does it have anything to do with Symbolics documentation!

Unable to discover the affiliation of its authors (not stated in the document itself), I can't tell where it did come from -- although it is hosted by several sites around the world, not just MIT. It shows internal evidence of font character code corruption, typical in the 2001 era of moving a document from one kind of system to another, or even just trying to change font-set. Note the prevalence of capital U's where an apostrophe belongs, and the clipped text in the second "competitive wheel" diagram. In fact, the diagrams show all the signs of being pasted in from an incompatible system: that wheel diagram is no longer circular, and the egregious box-and-pointer diagrams show the character misplacement typically exacerbated by PDF encoding.

None of that would have issued from Symbolics Press.

I may be a little defensive on the issue of paying attention to docs -- why else would I make a thoughtful response to a down-voted comment from someone with a history of them? At Symbolics, I was pleased that my technical writer colleagues shared the same title of MTS as us developers. I led the small team which developed Symbolics' document development system Concordia, and its document formatter -- which btw was contemporary with TeX and drew upon Knuth's published paragraph and equation layout algorithms. Also I personally inspected every pixel of every character (and all the pixels between) in every font used in Symbolics documentation. In a side-by-side comparison, Symbolics docs would look superior to something from 1986 TeX. One might see how even Prof. Knuth himself wished that Computer Modern had had the attentions of a professional font designer.

Finally, the paper itself explained that such in-house efforts were all of a piece with the rest of the company's engineering ethos.

DIY appendectomy? Fine, suture self.

As a mentor for a high school robotics club, I have learned the freeing joy of tinkering, as opposed to the engineering I have done my whole career. It's great to work with foamcore, X-acto knife, glue gun, little motors and electronics, and create something crappy and amateurish and _successful_.

No, suggests my experience. For me, after somehow squeezing through DiffEq, I met complex analysis, taught by the math department. I started the semester, got way behind, dropped it. Did that a second time. The third time my advisor wouldn't let me drop it, and I ended up with a gentleman's D (the only D in my life, aside from like handwriting in 3rd grade). The very next semester I took pretty much the exact same material from the EE department. I got it, I loved it, and aced it completely.

But 50 years later, I still have those gonna-flunk dreams.

Without getting all quantum about it, it seems to work by configuring the graphene as one electrode (or both) of a capacitor. As the graphene flaps in the breeze (actually Brownian motion, I assume), the changing geometry will change the capacitance. If there is a charge on the cap, then the voltage would flap too, inversely (Q = CV). A changing voltage would tend to push about a current (i.e. charge motion). If their diodes somehow have a negligible forward voltage drop, then brief moments of higher voltage on the flappy cap would push increments of charge onto the storage cap (the one to the right of the diodes) until the storage cap voltage rose to equal the peak flappy voltage (minus the diode voltage drop). When the storage capacitance is greater than the flappy graphene capacitance, the stored energy will be greater than the tiny increments (energy = 1/2 CV^2). Then every so often the storage cap could be switched to drive some load.

So why would there be a charge in the flappy capacitor? Well, a bias voltage is applied by this battery in the circuit. Ahem, before invoking any principles of thermodynamics, I'd like to see some detailed measurements, or even careful theory, of the current out of the battery and back into the battery, particularly w.r.t. the instantaneous voltages (P = VI), to prove that the time-average power delivered by the battery is precisely zero, or at least far lower than that putatively transferred to the load (light bulb in the animation). Otherwise it's behold, we found a high-resistance path for our battery to run a light bulb.

There is some precedent for semiconductor thermal magic in the Peltier junction. It makes one end colder and the other end hotter by applying electric watts to it, with no moving parts aside from the electrons and holes recombining, or something. But nobody sees thermodynamics being violated or extended there.

But here the magic is to take away thermal energy from one place, the flappy graphene (thereby cooling it) and moving the energy to the light bulb (thereby heating it). It seems you could then use any old heat engine to extract work by letting the heat flow from the resulting hotter place back to the colder place, getting "limitless power" for free from your perpetual motion machine. Conceivably it's a sort of heat pump that gets some multiplier above the battery power. But I think the burden of proof is on the Arkansas folks to explain how this can be. If I had more energy (no pun intended, really) right now I'd try to find the paper that the press release is based on, to see if there's a little more truth there.

Meanwhile, I doubt it.

Unless I'm creatively remembering, Dave Moon's EGC (Ephemeral Garbage Collector) in Symbolics Genera in 1985(?) had three generations.

I can recommend _The Happiness Hypothesis - Finding Modern Truth in Ancient Wisdom_, by Jonathan Haidt, as relevant here.

The book was suggested to me by a CBT practitioner. It languished on my shelf for several years because it sat adjacent to a bit of new age fluff, and I thought the subtitle sounded like it was another bunch of lost-wisdom-of-the-ancients drivel. I thought wrong: one should not judge a book by its cover.

The book is serious -- Haidt is a social psychologist at NYU Stern School -- yet eminently readable. It pulls in relevant aspects of the "ancient wisdom," evaluates them in the context of contemporary research, and shows where they can help us today and where they are outright plain wrong.

I can't say it has changed my life yet, but it has helped settle the inchoate bits that I have taken from the Enchiridon, Meditations, etc., into a useful way of thinking about the world and my place in it.

Now on to William Braxton Irvine...

Hatred. Stupidity. Devotion. Greed: The four horsemen of the new Apocalypse. --Salman Rushdie (I forget which book)