Richard Feynman Side Hustles

https://twitter.com/carl_feynman/status/2016979540099420428

68•tzury•1h ago

Comments

moralestapia•1h ago

This would be cool if only it made sense.

Supermancho•1h ago

I agree. It's not clear how adding a sensor "so that it adds back an oxygen molecule" works. shrug

boxed•1h ago

Because 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•1h ago

You're not really making things clearer.

What does "adds back an oxygen molecule" mean?

boxed•1h ago

That's an implementation detail no? Are you asking how to add an oxygen molecule, or how this makes the sensor better?

moralestapia•54m ago

Yeah, 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.

throwway120385•1h ago

Specifically, 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•30m ago

I 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.

comrade1234•1h ago

This 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•5m ago

I 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•52m ago

To 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•9m ago

I 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?

0-_-0•42m ago

Had to read it 3 times but it makes sense

celsoazevedo•1h ago

If you want to read the replies without an account:

https://xcancel.com/carl_feynman/status/2016979540099420428

https://nitter.net/carl_feynman/status/2016979540099420428

vonneumannstan•1h ago

So 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?

sd9•1h ago

I don’t know, can you do it?

spicyusername•59m ago

Nope! There are consulting companies all over the place filled with bids and not filled with Nobel laureates!

Ergo...

reactordev•53m ago

None that offer that level of work life balance though…

brk•50m ago

You 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•46m 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.

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