6 ms·
Candle Flame Oscillations as a Clock
- efavdb 1y agoVery cool. I've always wondered what the shape of a flame is and how one could use physics to derive it. anyone have any leads for this?
- nh23423fefe 1y agoseems like a very complicated simulation problem. i'd be surprised if you could derive from first principles. you need to model the atmosphere as environment, heat flow, wicking action, chemical reactions, fluid dynamics under gravity. Then model human perception to turn the spectral radiance into a perceived shape.
- IAmBroom 1y agoOr take a candle onto the ISS. Which they did.
- cpldcpu 1y agoThe third reference from the article provides some pointers (see also references there). https://arxiv.org/pdf/1803.10400 https://arxiv.org/pdf/1803.10400 But its not trivial at all, its a complex fluid dynamics problem. I stumbled upon all the "coupled candle oscillators" literature when I was looking for a shortcut to a semi-physical candle model. But there is no easy way out...
- efavdb 1y agoThank you! And appreciate the TLDR.
- kridsdale1 1y agoLook up some YouTube videos of candles or lighters used in zero-gravity. It’s a sphere. The candle shape on earth is caused by the weight of the air.
- waiquoo 1y agoFaraday did a whole series of lectures about a single candle, essentially covering a surprising amount of physics and chemistry. Super simple and fascinating: https://www.gutenberg.org/ebooks/14474 https://www.gutenberg.org/ebooks/14474
- NKosmatos 1y agoI was today years old when I learned that the frequency of a flicker candle flame is ~9.9Hz :-)
- JKCalhoun 1y agoThat is awesome. And I am so sad an individual that my first thought was of a software plug-in that would use this frequency to generate realistic candle-flicker effects.
- alnwlsn 1y agoTo continue this tangent, legend has it that some of those battery powered tea candle lights actually reuse the chip from cheap music playing trinkets. If you replace the yellow LED with a speaker, you might hear beepy christmas music or happy birthday. I've never found one myself (most of them have a better candle simulation chip than that), but they are apparently out there.
- cpldcpu 1y agoThis was 10-15 years ago. In between they used dedicated ASICS: https://cpldcpu.com/2013/12/08/hacking-a-candleflicker-led/ https://cpldcpu.com/2013/12/08/hacking-a-candleflicker-led/ And more recently simply microcontrollers: https://cpldcpu.com/2024/01/14/revisiting-candle-flicker-leds-now-with-integrated-timer/ https://cpldcpu.com/2024/01/14/revisiting-candle-flicker-led...
- kridsdale1 1y agoWhat a testament to the might of the global electronic supply chain that entire computers are cheap enough to be in disposable candles. Single use Vape-pens too. Some of those have displays and Bluetooth. Insane.
- epcoa 1y agoJust to offer an alternate perspective. While technically a PIC12 is a computer since it has I/O, tiny storage, a PC and an ALU - it’s hard to even think of it in the same category as what most think of as a computer. IMHO the takeaway is more what the bare minimum it takes to be a computer, which isn’t much. (In other terms, a PIC does not meet the DOOM threshold). PICs are so old and rudimentary that they started out as peripheral controllers for “real” computers in the 70s. It turns out you can do some useful embedded stuff with a basic chip, but even the newest of these are on 30 year old semiconductor tech at this point. That may sound jaded, on the other hand I do find mass production of modern level integration and speeds to still be marvelous. And as an EE, the “white” LED in the candle is more interesting than the uC!
- jkingsman 1y ago> Todays candles have been optimized for millenia not to flicker. Where can I learn more about that? My google fu is failing me.
- cpldcpu 1y agoThe self-trimming wick is the trick. Before that was invented, people had to use special scissors to trim the wick and avoid uncontrollable large (and flickering) candle flames. https://en.wikipedia.org/wiki/History_of_candle_making#Industrialization https://en.wikipedia.org/wiki/History_of_candle_making#Indus...
- IAmBroom 1y agoNot just flickering; smoking badly as the underheated, unburnt parts roasted outside the flame. Weirdly, the trick wasn't in changing the wick material to burn better, but changing their shape so they curled over (and remained marginally in the flame until burnt) instead of just sticking straight out: rectangular instead of circular braided string.
- Terr_ 1y agoInventions like those fall into my weird mental category of "I should investigate and appreciate these just in case I ever get stranded back in time."
- ck2 1y agoMy mind is blown candles flicker at a fixed rate Are we absolutely sure we're not in "the matrix" ?
- fallat 1y agoThe beginning of an alternative-universe candle computer that could've been used in the past.
- amelius 1y ago> as it mainly depends on gravity and diameter of the flame So cannot be used on a ship. Bummer. Our sea-faring ancestors wouldn't be happy with this clock.
- pinkmuffinere 1y ago> cannot be used on a ship. TIL there’s no gravity on ships. That’s why they float.
- tecleandor 1y agoSpace-ship, maybe? :P :)
- aidenn0 1y agoThere's lots of gravity in space too.
- jplrssn 1y agohttps://en.wikipedia.org/wiki/Marine_chronometer https://en.wikipedia.org/wiki/Marine_chronometer
- vunderba 1y agoFrom the article: > A fascinating fact is that the oscillation frequency is rather stable at ~9.9Hz as it mainly depends on gravity and diameter of the flame. This reminds me of when I first heard about Dolbear's law by which you can get an approximate measurement of the air temperature using the number of chirps per minute from a cricket. https://en.wikipedia.org/wiki/Dolbear%27s_law https://en.wikipedia.org/wiki/Dolbear%27s_law
- Scaevolus 1y agoCombining the two, you can make a thermometer using three candles, a cricket, and a webcam.
- HPsquared 1y agoMaybe you could also use the spinning fan from the computer that makes all these calculations, as another frequency reference. Although I'd want that particular calculation to be done in constant time, to avoid potential instability or hunting oscillation.
- legohead 1y agoWhile visiting a friend in Russia I was perplexed by the candle in his flat - it had zero flicker, was stable and unmoving. Eventually I learned how they heated the flat, with water flowing through pipes and heat radiation - so little to no air movement.
- pjerem 1y agoIsn’t it like this mostly everywhere ?
- viraptor 1y agoNo, central heating + radiators are somewhat region specific. For example Australia runs almost entirely on split system reverse aircons and electric heaters.
- pixl97 1y agoI've never had a house heated with pipes in the US.
- quesera 1y agoCirculating hot water radiators are pretty common in older cities/neighborhoods in the US. But I suspect the Russian example was radiant heating in the floor slabs, which will cause less air convection than hot water pipe radiators.
- gdbsjjdn 1y agoIn northern North America forced-air natural gas is pretty for single family homes. You have a gas furnace that blows heated air through ducts. It's supposed to be relatively inexpensive compared to electric baseboards, presuming you have all the natural gas infrastructure (or a big tank outside).
- adaml_623 1y agoI will Google but wanted to point out that I have no idea what "electric baseboards" are. It's funny how different houses are around the world. Even in similar latitudes/climate.
- vorgol 1y agoVery interesting article from the same guy where he reverse engineers the randomness of a flicker LED. https://cpldcpu.com/2013/12/08/hacking-a-candleflicker-led/ https://cpldcpu.com/2013/12/08/hacking-a-candleflicker-led/
- chrisweekly 1y ago> Now, it’s a curious thing that we try to emulate the imperfections of candles. After all, candle makers have worked for centuries (and millennia) on optimizing candles NOT to flicker? This reminds me of teenage me circa 1990 exploring electric guitar distortion and having an interesting conversation w/ my dad, who'd done a pretty serious paper on eliminating audio distortion as part of his CSEE degree from MIT.
- ahartmetz 1y agoI want to know the precision of that clock!
- fwipsy 1y agoAgreed, I kept reading through to the end for this. Arguably the most interesting part of this article is "Candle flickering is surprisingly regular and precise" but then they don't actually tell us how precise... Author! We demand satisfaction!
- deleted 1y ago[deleted]
- segfault99 1y agoIn the late 1980s I did an electrical engineering internship in a coal-fired power station over summer vacation. The gas furnace igniters ran continuously, but how do you detect presence or absence of burner flames against semi-apocalyptic background of ignited pulverised coal dust being air-blasted into the furnace? Have a little window and photosensor pointing at the burner flame and FFT. No spectral component spike at xHz (IIRC x ~= 13? -- it's a burner flame, underlying dynamics not same as for candle wick) --> ringing alarms, flashing lights.
- makeworld 1y agoWhat was the preferred way of doing FFT at that time?
- ants_everywhere 1y agohasn't the preferred way been Cooley-Tukey consistently since 1965? https://en.wikipedia.org/wiki/Cooley%E2%80%93Tukey_FFT_algorithm https://en.wikipedia.org/wiki/Cooley%E2%80%93Tukey_FFT_algor...
- segfault99 1y agoBingo. We certainly learned about Cooley-Tukey in undergrad back then. That power station was 100% Hitachi Heavy Industries turnkey. The control rooms had Hitachi mainframe and some minicomputers running proprietary real time OS (I guess). These were the days when the video controller for a colour industrial process control raster display CRT was a waist-high cabinet. So you'd transduce the flicker and then transmit it via analogue current loop to a rack in the control room annex, convert back to voltage, A/D it... and crunch the FFT on one of the control room computers. Something like that. Cheap distributed compute just wasn't a thing at the time.
- ants_everywhere 1y agothis is so cool, thanks for sharing :)
- ygritte 1y agoWhat a wonderfully hacky project! Noob question: How were the diagrams created?
- beeforpork 1y agoI love this. This is why we need science: a very interesting and curious fact is examined. Experiments are done and a toy is built based on the findings. It is all totally useless, excepts that human knowledge is brought forward and it is also fun. This is important. It is the reason why we are here. Life would be dull without these kind of highlights in my day. And for this, public funding is needed, because it makes people happy, and happiness is an important persuable goal of many public bodies. And because goal directed research (which is often dull and predictable) of stuff that can be financially exploited is funded anyway, non-publically.
- busfahrer 1y agoOnly tangentially related: In the Quake source code, they have strings to represent the intensity over time of a flickering light source: https://github.com/id-Software/Quake/blob/bf4ac424ce754894ac8f1dae6a3981954bc9852d/qw-qc/world.qc#L336 https://github.com/id-Software/Quake/blob/bf4ac424ce754894ac... // 3 CANDLE (first variety) lightstyle(3, "mmmmmaaaaammmmmaaaaaabcdefgabcdefg"); They range from a to z and progress through the string with time, so the candle starts out at medium "m" intensity for a bit before it goes dark ("a") for some time, etc.
- xorbax 1y agoTangential, but very interesting.
- docsaintly 1y agoI have recently become quite fascinated with how much of what we use daily relies on the laws of physics always working the exact same way. This is a wonderful example of that.
- bkitano19 1y agoyou might like https://en.wikipedia.org/wiki/Noether%27s_theorem https://en.wikipedia.org/wiki/Noether%27s_theorem