lambdatronics

>already a fairly radically super-human speech center >We're asking a speech center to do an awful lot of tasks that a speech center is just not able to do

Exactly!

>We need more parts.

Yeah, imagine what happens once we get the whole thing wired up...

>a way to generalize the compute graph as a learnable parameter.

Agreed. Seems analogous with how human mental processes are used to solve the kind of problems we'd like LLMs to solve (going beyond "language processing" which transformers do well, to actual reasoning which they can only mimic). Although you risk it becoming a Turing machine by giving it flow control & then training is a problem as you say. Perhaps not intractable though.

>What would it even mean for a particle to have an "action" (whatever that is) that is not minimized?

The particle doesn't have an action. The trajectory of a particle is what the action is defined in terms of. One way to think of it would be "it's a measure of how much the trajectory deviates from the one dictated by Newton's equations." Pretty much like what you said: "I can always find a measure that something else is always a minimum of."

About what a trajectory with non-minimal action would look like: it would be an arbitrary violation of the equations of motion for the system (ex: free particle moving in a zigzag instead of a straight line at constant velocity). Moving in a straight line at constant velocity is what Newtonian mechanics prescribes, and that trajectory will minimize action for the corresponding Hamiltonian.

Cool! I had been meaning to try my hand at a to-do app ever since I read "Getting Things Done" a few years ago, and I finally spent a couple weekends on it this month. The tree structure is 100% the way to go, and it's surprisingly uncommon as you note. It's been a fun & educational project so far. It's only SQLite file & some Python functions, no polish whatsoever. Probably will never get to the level of what you have, so hat's off!

I see what you did there with the Dr. Horrible reference! :D

IIRC sodium ion batteries have traditionally had trouble with rapid degradation due to the large size of the sodium ion, which disrupts the carbon electrode via swelling during intercalation. So I would be worried about the number of cycles they can last.

Thanks stuart8ol for all the detailed answers in this thread. I learned several new things today (use of compressors for fuel cells to increase power density, logic of airplane sizes). This is the stuff I come to HN for! Also cool to see you using H3X motors - I remember their launch here, I was excited for them.

Good luck decarbonizing aviation!

> But the trade off should not be "if there is any risk at all, then no"

I'm a kitesurfer and I'm with you 100%. I'm glad kiting is not banned in most places. Kiters die every year -- I knew someone who was killed, and I've had a couple close shaves. In fact, today I was kiting and witnessed a kiter get rescued by the Coast Guard. It's understandable that society would want to have some say due to the externalities (loss of productive members of society, cost of rescues, risk to bystanders, etc).

IMO it's not the case that 'no risk is acceptable' -- it's just that the risk tolerance for various things seems really arbitrary & out of proportion to reward. For instance, if we didn't accept any risks as a society, we'd ban alcohol & tobacco along with kitesurfing, skydiving and motorcycles, but we don't.

The paper says that this is only half of a solution: "Our investigation here has focussed [sic] on the fundamental Li-NRR performance at the cathode. Further developments towards a complete ammonia electrosynthesis system will require investigations of appropriate anode reactions while eliminating sacrificial solvent oxidation. A feasible initial strategy is to couple the Li-NRR with the H2 oxidation reaction, which has already been demonstrated but requires improvements in stability and activity. A more-desirable anode process is H2O oxidation, which presents larger challenges because of the potential interference of water with the Li-mediated process and vice versa."

This system involves ethanol as a sacrificial hydrogen donor: "The amount of ammonia produced in the 96 h experiments (3.9 ± 0.1 mmol) was around four times higher than the amount of ethanol present (1 mmol), indicating that it is not a completely sacrificial reactant but can also operate as a proton carrier."

First you want to displace natural gas for fertilizer production. But yes, if the energy efficiency is good enough and the electrolyzer costs are very low, it would make more sense than electrolyzing hydrogen and then running that through Haber-Bosch. Remains to be seen if either of those criteria can be met.

Probably not just yet. I calculated downthread that the productivity is something like 16x less per unit area than a hydrogen electrolyzer, so that would need to be improved to make it cost-effective probably. Also they don't mention the energy efficiency, only the "current efficiency" so I would assume the energy efficiency is also poor. Sounds like there's much to be done still.

Probably refers to "Coulombic efficiency." Ie, it takes 4 electron transfers to turn 2 H2 + N -> NH4, so that gives you a conversion factor between Coulombs of electrons (1 Amp of current is 1 Coulomb per second) and number of NH4 molecules produced.

Yeah, someone would have to get access to the paper to see if they state the energy efficiency. I assume that b/c they don't mention it, it is abysmal. There's pressure to put good results into the abstract.