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Richard Feynman Side Hustles
- moralestapia 9mo agoThis would be cool if only it made sense.
- Supermancho 9mo agoI agree. It's not clear how adding a sensor "so that it adds back an oxygen molecule" works. shrug
- boxed 9mo agoBecause then it doesn't alter the side of the membrane where it does the reading (plus one minus one equals zero). That makes the measurement more accurate.
- moralestapia 9mo agoYou're not really making things clearer. What does "adds back an oxygen molecule" mean?
- boxed 9mo agoThat's an implementation detail no? Are you asking how to add an oxygen molecule, or how this makes the sensor better?
- moralestapia 9mo agoYeah, how do you add the oxygen molecule, and how do you know when you have to do that? Elaborate and you'll find the issue with this setup.
- margalabargala 9mo agoThe issue here isn't the setup, it's with people understanding it.
- aipatselarom 9mo agoEnlighten us, then, savant[1]. 1: as in, one with detailed knowledge in some specialized field (as of science or literature)
- margalabargala 9mo agoThere are a lot of explanations elsewhere in this thread. If you've read all of them and still don't understand, I don't know how to help you further. Mainly I take issue with the person I replied to implying "I don't understand the solution, therefore there must be some functional issue with the solution."
- jstanley 9mo agoHow do you add the molecule? Well, you're not just dealing with single-digit numbers of molecules. Have an oxygen tank with a flow meter for example, open the valve to release the required volume of oxygen. The ideal gas law tells you how many molecules you let out. How do you know when you have to do it? The sensor tells you how many oxygen molecules you consumed, as a proportion of the current flowing. So just let oxygen flow into the tank at the same rate as you're consuming it. Which you know because the device literally measures how much oxygen it is consuming. I think the real issue is that the explanation in the tweet is from a physics perspective rather than an engineering one, which means it reads like it was implemented with impossible magic.
- aipatselarom 9mo ago>open the valve to release the required volume of oxygen Mega LMAO. I can assure you this is not what's going on, at all. Also, if you release oxygen in gas form into the liquid you're going to run into a zillion other problems. One of the golden premises of measuring things is to avoid altering what you're measuring, lol.
- adrianmonk 9mo agoIt means you do an electrochemical reaction that releases an oxygen molecule, like the original explanation said. It doesn't really matter what reaction it is, but it could for example be electrolysis, where you split 2x H2O into 2x H2 and 1x O2. The point is this reaction is reversible. In one direction, you end up with fewer O2 molecules than you had before. In the other direction, you end up with more.
- throwway120385 9mo agoSpecifically, if you assume a partial pressure of Oxygen and of all other gases on the electrode-side of the diffusion membrane, then you'll only see a certain number of "ionization events" per time, and you're limited in how much electrical signal you get by how fast oxygen can diffuse across the membrane. This is likely driven by maintenance of a partial pressure within the membrane. However if you re-ionize the oxygen that you deionized, then the partial pressure is much closer to equilibrium, and therefore the partial pressures are only dependent on the amount of oxygen outside of the membrane instead of being dependent on both the ionization rate and the recovery rate through the membrane. It probably makes the calculation a lot faster and more closely dependent on the environmental presence of oxygen which is what you want.
- brk 9mo agoI think this was primarily about speeding up the measurement time. With just two electrodes you had to wait for the device to achieve equilibrium with the material being measured. If the concentration of oxygen on the probe side of the barrier was higher or lower than the material side you would get false measurements, particularly in low oxygen scenarios because you have oxygem trapped in the probe. By keeping the state of oxygen inside the probe constant and replacing consumed molecules you now can measure almost instantly.
- Panoramix 9mo agoYes but how do you do that? that magical third electrode sounds harder to make than the original problem. Edit: I think I get it now, it's a chemical reaction. By applying a voltage with some polarity to the 3rd electrode you can run the reaction in reverse. Still very hard to achieve because you have to make sure the reactions happen at the same rate with the same efficiency, which is far from trivial. This must be a very high end sensor for all this effort to make sense.
- direwolf20 9mo agoAn oxygen molecule does some chemical reaction on the sensor electrode that releases an electron, maybe it's made of iron and turns into rust. If you supply the same current to another electrode to do the opposite reaction, maybe one made of rust that turns into iron, it balances. The sensors must be consumable with a certain lifetime.
- fuzzfactor 9mo agoYes. Zinc can do this too. But I like silver, its oxide has decent conductivity. One of the common arrangements on a basic two-electrode sensor is to have one gold electrode to make contact with the electrolyte, and the electrolyte provides conductivity to a sacrificial silver electrode. With electrolyte exposed to the atmosphere through an oxygen-permeable membrane. As oxygen makes its way through the membrane, it is consumed by the silver at a steady rate and equilibrium is achieved relative to how much oxygen is in the atmosphere. This generates a steady current which is amplified to move a needle on a gauge, where there are knobs to adjust the meter until it displays the correct amount of oxygen during calibration against a known concentration. And must also be calibrated to display zero when there is no oxygen. Eventually even if the membrane never gets fouled the oxidized silver builds up in the electrolyte chamber and response deteriorates so maintenance is needed. Remove the membrane, polish the silver, put in fresh electrolyte, new membrane, and re-calibrate. Adding a third electrode opens up a number of further possibilities. One of them is the option to use an additional inert gold or platinum contact or a salt bridge as electrical reference against the original gold or silver as the sensor. Plus using a more complex circuit than a plain amplifier, apply controlled responsive current to the sacrificial silver at the same time. So rather than directly amplifying the current produced by different concentrations of oxygen existing in the electrolyte (and waiting for it to equilibrate), instead with 3 (or 4) electrodes the ionic silver concentration in the electrolyte can be maintained electronically in a steady state, and as oxygen permeates, the current required to replace the consumed silver is designed to make a dfferent kind of meter move the needle the same way as above. In this way the oxygen concentration in the electrolyte varies to a much more limited extent compared to waiting for it to be depleted from a high amount to zero before the meter will bottom out. This can be equivalent to constant-ion electrochemical titration. Disclaimer: I always like to handle things like this like lives depended on it, because lives depended on it.
- comrade1234 9mo agoThis way you're measuring change in oxygen concentration. As more oxygen comes into the compartment in order to equalize with the outside you consume and at the same time produce more oxygen. You measure the change in rate of oxygen consumption/production. It is always consuming/producing oxygen but the rate changes with the concentration. At least that's what I assume.
- spott 9mo agoI think of it differently. Before, you measured diffusion rate of oxygen and inferred oxygen concentration from that (the concentration outside the chamber is always greater than the concentration inside). Dirty membranes etc all changed the rate of diffusion, which caused issues. After you measure oxygen concentration directly (the concentration inside and outside the chamber are always the same).
- speak_plainly 9mo agoTo use an analogy with some metaphors: The sensor is like a sealed room with a screen window that only lets in oxygen. To get a reading, every molecule that enters is smashed to create a tiny spark of electricity. However, because the oxygen is destroyed to create that spark, it creates a suction effect, causing more oxygen to rush into the room to fill the void. This creates a major flaw: if gunk builds up on the screen, it slows down the flow of incoming oxygen. The sensor, which only counts sparks per second, is tricked into thinking the oxygen level outside is low, when really the window is just dirty. By adding a third electrode to replace the oxygen every time one is smashed, you maintain a perfect balance and eliminate that suction. Because the room stays full, the sensor no longer relies on the speed of the oxygen rushing in; it simply measures the steady state of the oxygen already there. Even if gunk gets on the window, the sensor won't be starved of a reading. It might take a few extra seconds for the levels to settle, but the final number will be 100% accurate because the sensor is no longer emptying its own room to get a count.
- Coeur 9mo agoI still don't get it. The outside is dirty, right? He said in his post "You dip this probe into beer, sewage, or canned food a-stewing". So when you say "when really the window is just dirty" I don't get it - yes it will always be, because that's what it is placed in, no?
- speak_plainly 9mo agoA dirty window only ruins the reading if you are measuring the speed of the oxygen passing through it. The three electrode design stopped measuring speed and started measuring balance. Unless the gunk is a total airtight seal (which is rare on the scale of an oxygen molecule), the sensor will eventually reach the right answer, whereas the old version would fail.
- Coeur 9mo agoSo dirt as a factor that clogs up the sensor does not play into it at all? It's all just about moving it into different environments to measure?
- 0-_-0 9mo agoHad to read it 3 times but it makes sense
- aorloff 9mo agoTrust me, if we all understood Richard Feynman the first time he said something, the world would be a very different place.
- moralestapia 9mo agoThat's very cool and edgy but (Richard) Feynman didn't say this.
- deleted 9mo ago[deleted]
- rcxdude 9mo agoThe current is measuring the rate of the reaction. With the two-terminal design the rate of the reaction is proportional to the rate of diffusion of the oxygen into the area where the reaction is taking place, which is related to the oxygen concentration around it but also can be affect by other things. With the third electrode, the current is proportional to the concentration of oxygen in the area around the sensor directly, which will equalise with its surroundings much more consistently than the rate of diffusion. (A quick google brings up this document which describes the principle. No idea if this is the company in the story: https://semeatech.com/uploads/Tech_Docs/AN%20161205.pdf https://semeatech.com/uploads/Tech_Docs/AN%20161205.pdf )
- celsoazevedo 9mo agoIf you want to read the replies without an account: https://xcancel.com/carl_feynman/status/2016979540099420428 https://xcancel.com/carl_feynman/status/2016979540099420428 https://nitter.net/carl_feynman/status/2016979540099420428 https://nitter.net/carl_feynman/status/2016979540099420428
- vonneumannstan 9mo agoSo do you have to be a god tier Nobel Laureates to get this kind of gig where you just learn about a business and then offer random suggestions that might or might not help them and charge obscene fees for the privilege?
- deleted 9mo ago[deleted]
- spicyusername 9mo agoNope! There are consulting companies all over the place filled with bids and not filled with Nobel laureates! Ergo...
- reactordev 9mo agoNone that offer that level of work life balance though…
- brk 9mo agoYou definitely don't have to be god tier anything, you just need to know at least a little more than the companies you are consulting for. This kind of work has been my primary income for the last 4 years or so. Nowhere near on the same level as Feynman, but I know enough about enough other things that I get a lot of reputational referrals.
- zxcvasd 9mo ago>you just need to know at least a little more than the companies you are consulting for. sometimes (i'd argue often, actually), you don't even need that. simply having an outside/fresh perspective and the fact that you aren't part of any of the existing groups/silos is valuable.
- rdiddly 9mo agoProbably true, but to get the job in the first place you probably need some sort of showy, impressive credentials.
- deleted 9mo ago[deleted]
- Fricken 9mo ago[flagged]
- Uhhrrr 9mo agoIt is a neat story about Richard Feynman. What about it reads as "Nazi" to you?
- deleted 9mo ago[deleted]
- beeflet 9mo agoI don't recall this "richard feynman" guy ever publicly supporting trans rights
- zahlman 9mo agoThe complaint is about it being a post on X. Some people around here really do think that way about Elon Musk.
- amazingman 9mo agoWhile I don't agree with the "this shouldn't be on HN" part, people thinking Elon is a Nazi isn't exactly unreasonable. He literally sieg heil'd an audience at Trump's inauguration. Twice. Call it trolling or whatever you like, but he did it and the outcomes for such an act are ... predictable.
- antonvs 9mo agoThe way people continue to use X is a perfect example of Arendt's banality of evil: that moral wrongs can be enabled by ordinary people, acting through conformity, careerism, convenience, and thoughtlessness. They don't have any deep ideological commitment or overt cruelty, they just don't care enough. They justify themselves with claims such as "it's the way things are," "not my role," "everyone does it", or that it doesn't really make a difference. But if everyone on X that doesn't explicitly support fascism and Nazism stopped using it, it would make an immediate difference. X would turn into something more like Truth Social.
- thr0waway001 9mo ago[flagged]
- rustyhancock 9mo agoPeople are giving such bizarre examples for why it helped. Just think of a thermometer. If it removes heat as it measures it (consumes oxygen) then it will measure everything too cold if the system can't replace the heat that's removed (this is like having an insulated thermometer). If your thermometer replaces heat as it removes it it solves this issue. When is this an issue for a thermometer? If your thermometer is too large in terms of heat capacity for the objects you're measuring the temperature of.
- ekaryotic 9mo agomany of the older analog low impedance multimeters drew so much current that they affected the circuits they were trying to test, requiring a high impedance digital multimeter instead. it's a similar problem, and i'm sure the physicist was aware of it, but didn't like to admit it.
- mattmcal 9mo agoI had to read this twice to understand it. Stated succinctly, it sounds like the company's sensor measured the rate of flow of oxygen through the sensor, which would give a reduced reading if the cross section is obstructed. Feynman's sensor, by contrast, directly measured the concentration of oxygen in the sensor, which gives the same result every time once the sensor is at equilibrium with the environment.
- EvanAnderson 9mo agoI feel like the company might have been Yellow Springs Instrument (YSI, now a division of Xylem). The dissolved oxygen sensor (the Clark electrode) was invented by Dr. Lee Clark at Antioch University (Yellow Springs, OH) and commercialized by YSI in the 1960s. A friend of mine worked at YSI from the late 60s thru the 80s on biosensors (glucose and lactic acid, using the Clark electrode as the basis) and worked directly with Dr. Clark. Carl Feynman was born in 1962, according to what I'm reading, so if he was 14 that would have put this story in the time period early in the commercialization of these sensors. Some good background: https://derangedphysiology.com/main/cicm-primary-exam/respiratory-system/Chapter-422/principles-oxygen-measurement-clark-electrode https://derangedphysiology.com/main/cicm-primary-exam/respir... https://www.anaestheasier.com/the-clark-electrode/ https://www.anaestheasier.com/the-clark-electrode/ I'll have to hit my friend up to see if he knows anything about this. I'm certain he'd get a kick out of reading this, if nothing else.
- IAmBroom 9mo agoSay hi to Dave Chapelle while you're there! ;) Serious question: Is Dr. Clark the guy who invented the modern soda can pulltab, too? Someone who lives in YS invented it, and made a kajillion dollars by solving the problem of dangerous, sharp-edged pulltabs littering ... everywhere.
- waynesonfire 9mo agoSaw this twitter response, > Do you have a similar speaking cadence as your dad? I can almost hear this in his voice. I experience the same. Wonder if Carl asked chatGPT to write it in Richard Feynman style? :/ I troll; Regardless, it made me happy to hear Richard in Carl.
- getpost 9mo agoOff-topic, but I was interested to read Carl's Twitter bio[0], "I’ve spent a lifetime switching my Special Interest every year or two. By now I’m surprisingly knowledgeable in a lot of fields— a skill now obsoleted by AI." That hits a bit close to home! [0] https://x.com/carl_feynman/ https://x.com/carl_feynman/
- timschmidt 9mo agooof. right in the self-image.