This is something of an aside on your first paragraph and lh712's. The theory of special relativity (and field theory in general) can be "derived" (as done in e.g., Landau, Lifshitz _Classical Theory Of Fields_) without empirical observation using concepts known to Galileo/Newton (if they count as "Medieval") - just with different assumptions/ideas about inertial frames. If you assume there is any phenomenon with a fixed observed speed in all "inertial frames" then you get special relativity with Einstein's gestalt-switch. After that it is, like so much in physics, a matter of thinking of an experiment to distinguish what matches capital-N Nature best.
Thinking otherwise mistakes a fundamental error that the only way for something to happen is how it historically happened. Reconciling observations forced relativity historically, but it could have been sussed out without those. That there were very fast but finite speed phenomena (which could motivate relativity reducing to Newtonian models) was seen in 1676 by Rømer with the speed of light and eclipses of Io, a Galilean moon of Jupiter. It probably could have been done with Galileo's telescopes in 1610. (That is just one example of a phenomenon with a very fast yet finite speed to suggest other experiments to test that "hypothetical relativity".)
TBH, this all relates to teaching "physics without calculus" and that sort of thing. Is the most clear presentation/derivation that which mirrors the history of our muddled yet ever demuddling ideas or that which starts from our most thoroughly demuddled ideas, best notations, etc.? The momentum is certainly the historical approach, yet there are notable exceptions.
Well, exactly, and I think that that is in line with what I originally wrote, and which is that you need the general relativity principle (by general I don't mean the general relativity but the concept of the equivalence of inertial frames) and the theory electromagnetism. (By the way, I am familiar with the Landau--Lifshitz textbook.)
(1) The relativity principle is exactly what you refer to yourself. You can't apply "Landau--Lifshitz"-like arguments without it. (And I don't think these principles count as medieval knowledge.)
(2) I mentioned electromagnetism, because you need some clue for the concept of an absolute speed that is same for all inertial observers. This is very counterintuitive from our everyday experience, and counterintuitive from the point of view of somebody living in the time of "Galilean" or Newtonian mechanics. Theory of electromagnetism is the only thing that I am aware of, that is nearly (by a stretch) accessible at the level of "medieval" knowledge, from which the concept of constant speed follows. (Historically: Maxwell's completion of previously inconsistent equations of electromagnetism yielded a wave solution propagating with the constant speed of light. This was interpreted in terms of the ether originally, but it is a strong hint in itself for Einsteinian principle of relativity; and a reasoning along the lines you alluded to can them be applied, at least in principle.)
Yeah. My point was mostly to expand upon your original post - sorry if it sounded like I disagreed. You say the same in your original "iteration of speculation and observation". Everything else is about what "derive" and "knowledge" might mean (I agree "medieval" usually means pre-Renaissance and Galileo is modern-era), how much empirical "proof" is in "derive", etc. However, all you need for "possible" is "the idea", some "consequences", and ways to test.
So, to push back a tad on your more recent "only thing that I am aware of" and to maybe explain my above point better, I do think there was enough information/ideas in the abstract in Galileo/Newton/Leibniz' times to suggest the idea. Leibniz himself pushed back hard on Newton's absolute space/time (long before Mach). For Leibniz, it would have been counterintuitive space/time vs. counterintuitive fixed speed. So, that pushback itself could have been enough of a "clue" in your terms -- in some alternate timeline -- to drive a speculation-observation cycle starting from different inertial concepts - with Galilean moon eclipses then enough a clue that fast speeds existed to fool our slow-speed intuitions. (And all this in the "modern era".)
So, I continue to think it "not impossible" that the relativity principle could have arisen before any EM theory at all -- it just didn't. That matters for these kinds of speculative questions about what information horizons support what developments. A single "fast enough" fixed speed is is not that wild & crazy. The modern world has a zillion obscure physics theories like that (mostly just because so many more people work on that stuff, but that's a probability thing, not a possibility thing, and I suppose also partly inspired by how physics turned out - so not truly independent). History is littered with things that could have happened, but didn't.
P.S.: and apologies for "mistakes a fundamental error". I of course meant "makes a", if you wanted any evidence that I was not an LLM. ;-)
Thank you for your reply! Yes, I fully agree that meaning of "derive" and other related concepts are non-trivial. (And I actually changed my own "working definition" between my two posts; while in the first one I was leaning more towards theories anchored by observation, even if indirectly, in the second one I slipped into more mathematical/philosophical perspective. The second part of my first reply makes sense only from the first kind of perspective, because in that part I imagine that the observed reality, even at the medieval level of knowledge, might perhaps necessitate a particular kind of underlying theory, from which the relativity principle would then "fall out". That was the only way I could think of at that moment how SR could have been "derived" without further observations.)
Your points about Leibniz are very interesting, and while I find that line of thought fascinating I must admit my own lack of knowledge of the historical context. In any case, thank you for pointing out that idea!
Another lesser known wrinkle along these lines is that if more of Aristarchus of Samos' work on heliocentricity had been developed into a "calculational framework" for planetary motion by a contemporaneous Ptolemy competitor (a la Copernicus in 1543), various relativity ideas might well have started in 270BC instead of 1600 AD.
Aristarchus was already WAY ahead of a few games - making a guess that "absolute rest" was illusory and tiny stars were similar to giant Sol. If not for Archimedes' serious star power, we might not even know of Aristarchus' heliocentric ideas! Relativity ideas of various kinds are short intellectual hops from "the absolute rest of your intuition is illusory".
Aristarchus and his supporters just had to assert The Stars were very distant -- far enough for there to be NO PARALLAX! Various "coincidences" all conspired to suppress Aristarchus' plausibility, like: A) Just HOW DISTANT stars are/local galactic stellar density &| B) poor human VISUAL ACUITY relative to C) Earth ORBIT vs. Sun LUMINOSITY (parallax baseline) & maybe existence of Moon to vent atmo &| D) VERY SLOW (3 millennium) development from near prehistoric glass (1500BC) to grinding lenses for human eyes in the 1300s AD leading to Galileo's telescopes & etc. If ANY of (A)..(D) were about ~10x better (ALL of which are imaginably so), the day that universe changed could've been much earlier. Heck, even if Aristarchus just had a really good spin doctor like a major religion pushing the plausibility of "Sun=A close Star", that might've been enough.
Archimedes almost invented the underlying ideas of integration and limits and all that, too. Close but no cigar, but (had that been in hand) analytic geometry and differential equations are short steps away. I mean, Newton surely noted the equivalence of gravitational and inertial "mass" (charge vs. kinematics) which is the weak principle of equivalence of GR, after all. Like I said - "littered". ;-) There are probably whole books written on the topic (or adjacent topics) of "All the Things Humanity Nearly Figured Out Earlier" that have a more historical bent than the usual "sci-fi tilt".
Something Dan does not observe in his article (perhaps Jamie does elsewhere? edit: or even Dan elsewhere) is that the same problem which makes the memory latency benchmark unrealistic (or at least misleading) often impacts hash table lookup benchmarks as mentioned at https://github.com/c-blake/bu/blob/main/doc/memlat.md and probably many other benchmarks. Essentially, CPU work prediction/speculative execution has become so good that much care is often required to measure latency rather than reciprocal throughput. This all started in the 1990s (or probably earlier with Cray), but I guess there's been an ongoing educational failure/oversimplification tendency.
Of course, throughput at one "level of work" is often latency at a higher level (like command-to-command execution, for example). So, "what matters" might be throughput or "latency". It all depends. :-) People often fiddle with such semantics to market methods, products, ideas, ... and marketing is often at cross purposes with understanding.
I just tried a tar file of a git clone of the linux kernel sources where the most recent commit is 72c395024dac5e215136cbff793455f065603b06 (early Feb of this year). zstd -19 got a slightly smaller size (3582930348 bytes vs bz3 -b 511's 3597411687 bytes or 0.4% advantage to zstd). More significantly 4-core zstd decompression was 2.05 seconds vs a whopping 297 seconds for bzip3 -dj4 - 145x or over 2 orders of magnitude slower (about as much time to decode as to encode in the first place). bzip3 1.5.3 compiled with gcc-16.1.0. Granted, the .git objects are all compressed already and uncompressed tar-ball was only 5426667520 bytes, but even so...A lot of people care about fast(-ish) decompression. Maybe I did something wrong? Maybe `rm -rf .git` first would be a better benchmark?
The "scatter line plot" in TFA is all same shade of red on white with no year labels. This seems like a missed visualization opportunity. Using some kind of color scheme/gradient to represent the 1979-2026 years in a way that can show long-term "trend". (A 50 frame movie at, say, 5 fps with same axes or maybe "all years" as faded background as the current year pops around in bold is another possibility, but a scientific paper format doesn't let people do .mp4s.) I know I've seen multi-colored "scatter lines" in IPCC reports. Seemed worth asking rather than doing it myself.
Don't forget head, tail, mount, strip, touch, etc.
My GF when I was first learning these names was convinced the Unix principals did all this quite deliberately and "finger" was her headliner argument. Evidently, even in 1971 someone complained: https://blog.robertelder.org/intro-to-pinky-command/ (relevant to that source, Usenet/Net News/mailing lists may be another social network which never exactly died and even today LKML, zsh-workers, etc. are main communication avenues).
I don't know what @winding means, exactly, but at best this seems highly misleading. Nim had babel packages by around 2010 (when it was called Nimrod and there was a Tower of Babel name scheme) and then nimble packages since 2014 or so. Also, literally 30 seconds on https://nim-lang.org (click on Documentation) and you get to https://nimble.directory/ , search for index and get to adix which has all sorts of efficient Table variants.
There has never been much prog.lang. benefit from being "in the stdlib/core" in Nim (unlike Python or Go, say). The benefit is more "software distribution" for the dependency allergic, but the Nim culture is much less micro-deps than seems in vogue lately. All that said, I think having a more batteries core distribution is valuable - just less than you might guess - and practically that needs delegation.
And knowing the magic keyword search `adix` to arrive at a prerelease library that you yourself wrote. That not's exactly an endorsement for discoverability. Unless I'm missing something, Nimble is essentially stateless. You have no sense of how many times or how recently a library has been downloaded. These are important proxies.
> There has never been much prog.lang. benefit from being "in the stdlib/core" in Nim (unlike Python or Go, say) … more batteries core distribution is valuable - just less than you might guess
Yeah, I don't think this is the community's strong suit. It strikes me that Araq is tired of explaining himself (but doesn't care to consolidate discussion into ADRs), so when a well-meaning, would be contributor like the parent-poster comes along they get shot down and we lose them.
I only said anything at all because the implication was not "missing minor nits about whatever your favorite proxy for 'will rely' is" but rather "nothing at all". FWIW, the keyword was "index" and the result was adix, and I only meant the package system & "a" directory were discoverable. Exact keyword search systems indeed make discovery harder, but that is some whole other complaint. There are always many complaints.
There are a million ways to define both "top 10 language" and "weak std lib", but the C stdlib is not great and C++'s was bad enough to spawn Boost. And I'm sure many firms all but say "do not use" parts of many top10 stdlibs. In any event, we don't disagree that Nim's stdlib being stronger would be better or that poor delegation or unconsolidated discussion are problems. We disagree on very little, including I'm sure that there is more to a PLang than its stdlib.
What is present/missing in any stdlib (or really in almost anything period) is also often much more subtle and subjective than simple sales pitches one hears. To be concrete, there are "useful" (to someone) things in the Nim stdlib not in either Python's or Go's like std/critbits, std/pegs, ropes, packedsets, intsets, editdistance, etc. Nim stdlib substring search behind "xyz".find() is layered to let you, if you want, pre-build a `SkipTable` (the way regex engines let you pre-"compile" regexes). Subtle in diversity of both kind and granularity and subjective as in "who cares?"
Yes, all that and more is all available in all the ecosystems of anything "popular", but that brings you back to "trust proxies", like "prerelease" numbers, a very weak one, IMO. E.g., I have never used a neovim with a version >0.13, but it's been a trooper; one man's 0.7 is another's 7.0. TRUST IS TRICKY! A count of distinct reliers for some values of "distinct" and "rely" or various update patterns would be better (have their own issues, of course, but at least measures "company" as in "what misery loves", LOL).
There is a python3 variant in this thread [1], but if that is not "standard enough" (as someone else may have mentioned bash itself is not POSIX), this awk would also work { Warning - this awk is 1000s of times faster than the bash. So, you really probably want that sleep { and sure 100s of times faster yet may be possible. } }:
#!/usr/bin/awk -f
BEGIN {
# Split on spaces so multi-byte utf8 works
nText = split("♥ P E A C E ♥ F O R ♥ A L L", tmp, " ")
for (i = 0; i < nText; i++) text[i] = tmp[i + 1]
color0 = 12; color1 = 208 # xterm-256 color cube range
nColor = color1 - color0 # Could be a pretty gradient
w = ENVIRON["COLUMNS"]; if (w == "") w = 80
h = ENVIRON["LINES"]; if (h == "") h = 24
freq = 0.2
for (t = 0; 1; t++) {
x = int(w/2 + w/4*sin(t*freq) + 0.5) # x pos ~ sine
color = color0 + int((nColor*t)/h)%nColor # cycle colors
ch = text[t % nText] # cycle chars
printf("%*s\033[38;5;%dm%s\033[m\n", x, "", color, ch)
fflush()
# system("sleep 0.1") # awk has no builtin sleep
}
}
As to "bug reports", the T-shirt published script also fails with LC_ALL=C for me as mentioned else-thread.
FWIW, I think ancient practice to reach for `bc` instead of `awk` or even the arithmetic built into shells often annoys. The only reason I keep `bc` installed at all is to compile Linux kernels. Someone had some patch set to Linux to eliminate this very dependency many years ago now.
That Matrix visual was actually specifically mentioned as an inspiration in the video by the designer being linked to/discussed elsethread (e.g. https://news.ycombinator.com/item?id=48830326 )
For anyone that cares, this is a slightly less stupid Python version:
#!/usr/bin/env python3
from os import environ; E = environ.get
from math import sin
from time import sleep
text = "♥PEACE♥FOR♥ALL" # The text to sine-scroll animate
nText = len(text) # Number of utf8 chars
freq = 0.2 # Frequency scaling factor
color0 = 12 # xt256 Color cube segment 12..<208
color1 = 208; nColor = color1 - color0
(w, h) = (int(E("COLUMNS", 80)), int(E("LINES", 24)))
t = 0
while True:
x = (w/2) + (w/4)*sin(t*freq) # x pos via sine value
x = max(0, min(w - 1, int(x + 0.5))) # bound to tty width
color = color0 + ((nColor*t)//h)%nColor # cycle colors
ch = text[t%nText] # Get char & Use xterm-256 color escs
print("%*s\033[38;5;%sm%s\033[m\n" % (x, "", color, ch))
t += 1
sleep(0.1) # original used bc shell outs to rate-limit
Thinking otherwise mistakes a fundamental error that the only way for something to happen is how it historically happened. Reconciling observations forced relativity historically, but it could have been sussed out without those. That there were very fast but finite speed phenomena (which could motivate relativity reducing to Newtonian models) was seen in 1676 by Rømer with the speed of light and eclipses of Io, a Galilean moon of Jupiter. It probably could have been done with Galileo's telescopes in 1610. (That is just one example of a phenomenon with a very fast yet finite speed to suggest other experiments to test that "hypothetical relativity".)
TBH, this all relates to teaching "physics without calculus" and that sort of thing. Is the most clear presentation/derivation that which mirrors the history of our muddled yet ever demuddling ideas or that which starts from our most thoroughly demuddled ideas, best notations, etc.? The momentum is certainly the historical approach, yet there are notable exceptions.
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