robryk @robryk@qoto.org

@billseitz @mcc

If they drop _codepoints_, then they amusingly will treat strings differently depending on whether they specify e.g. accented characters via individual codepoints or using combining codepoints for accents.

@mcc

Sometimes the information isn't there. E.g. "I want to tell if this UTF-8 string contains Japanese or Chinese pictographic characters" is sometimes unanswerable.

@grimalkina Do you mean https://www.nature.com/articles/s41593-019-0502-4?

@cstross

I think iPhones themselves contain barometers.

@johncarlosbaez I'm confused. The system as described only delays images of satellites by a few days, but at the same time tells everyone explicitly what was redacted those 3 days later (you can run the same comparison on the published images and compare the results with previously published alerts). So this only makes sense if what is protected are images of events, and only for a short time. Do I misunderstand?

@niconiconi any divisions present? If not it's really bizarre, because casting down to u32 could be pushed off to the very end.

@falsevacuum or rather the electron (if they aren't all the same one, why are they identical?) :)

@mcc this sounds similar to the reason why some types have an into_parts method and a corresponding from_parts "constructor".

@_thegeoff

I've found a bit more on how that works and it's amusingly simple (tl;dr with a good timing source one can very precisely integrate frequency over time by just counting): https://spie.org/publications/spie-publication-resources/optipedia-free-optics-information/tt61_541_laser_interferometer

The thing I'm still missing is how one gets two closeby frequencies _at orthogonal polarisations_ out of a laser.

@_thegeoff

Sadly, this transformation changes everything far enough that IMO beats do not map to much of anything interesting in the original configuration.

To see that this mapping changes things very significantly, notice that a base frequency and a few harmonics map to something that has no base frequency, but is rather a mixture of a few unrelated frequencies and their common harmonic. This IMO means that interesting relationships between frequencies are not preserved.

If we talk about beats specifically, then the frequency difference "on the audio side" here is a nonlinear function of the frequency difference "on the light side", so even if we were to consider some hypothetical creatures that have very short averaging timescales in vision (so that they can perceive beats at differences e.g. as small as a few MHz[1]), this map to something weird on the audio side (the minimal frequency difference will not be constant over the range we're considering).

[1] This does not necessitate them having awareness of such short time intervals btw.: a human, with help of an FM radio receiver, can do something equivalent to detecting beats with frequency differences of small hundreds of kHz. A creature could have sense organs that can do something similar without their conscious processing having to run at higher speeds.

(BTW. This sounds like a potential worldbuilding idea for a short story.)

@munin @SwiftOnSecurity

> It doesn't - nor can it.

> The shape that is in my mind is unique to me, and will be different in many respects to the equivalent shape in yours -

I'm confused -- how is this related to how well the model (either the one you have or the one you managed to communicate to someone) matches _reality_?

When someone tries to describe a model they have and I don't fully trust it's correct, I desire more precision in what they're saying so that I can evaluate it better. I could try to understand it fully first and then evaluate it, but that might take a lot more time and effort than us both figuring out the model's wrong in some way by having me choose pieces to ask more precision about.

@munin @SwiftOnSecurity

> Communication isn't about precision of words; it's about describing the shape you have in your mind in a way that allows others to create that shape for themselves -

Why would they believe this shape matches reality without precision (or at least ability to call up precision)?

@_thegeoff wait, but didn't this map frequencies to (some multiple) of their inverses?

@_thegeoff wait, but didn't this map frequencies to (some multiple) of their inverses?

@dougmerritt @johncarlosbaez

I don't think children are likely to start with that worldview based on anecdotal evidence: I don't know anyone who initially considered Zeno's (Xeno's?) paradox to be intuitive (@timorl , did you?). When I first learned of it (sometime in primary school) it seemed contrived to me.

@_thegeoff

IIUC you interfere two frequencies that are closeby and thus you can read out the value by looking for a non-zero-frequency envelope in the output. I haven't read enough to know how that works: do they use nonlinear material to literally create a MHzish signal, or do they sample the output light at a MHzish frequency.

(This gives you better tolerance wrt stray light, but I don't know if this is the only reason.)

@johncarlosbaez

Is instantenous speed a central example here? I'm asking because I'm surprised to find it's not an intuitive notion: I don't remember fellow classmates struggling with it (and I do remember struggles with abstractions such as a function that happens to be linear. I will probably ask my 6~8yr old "nephews" in the coming days; suggestions on concrete questions that show the difficulty are very welcome.)

@bert_hubert @johncarlosbaez

Solid state physics had lots of such, ttbomk basically at any time. (I'm not sure whether y'all would call it fundamental physics though; it's in large part about creating models for situations where we already think we have good, albeit intractable, models.)

@_thegeoff btw I've realized that heterodynic(sp?) interferometry is a thing, but haven't managed to dig up how it works exactly (in particular, what's the nonlinear mixer that can accept light and can emit RF, or how does it work without that).