You said it was a "logical fallacy" to even ask the question.

Bingo.
AI, if it advances along the lines that have been laid out for it, could very reasonably reach the point where it can replace humans in most jobs.

Maybe some hitherto-unsuspected new type of jobs will pop up that AI can't do. But we don't know that.

Even if AI and robotics can't do all jobs, if it replaces a high fraction of work without replacing that with other work that people will pay for, our current economic paradigm (as the grandparent post phrases it: "if you don't work, you don't eat") fail if there is no work available.

And your authority for making that pronouncement is?
Many things that have never previously happened in human history have happened.

This is a logical fallacy. It's like asking, "What if we were to build an immovable object that could stand up to an irresistible force?" It's a contradiction.

You apparently don't know what a logical fallacy is. "In my opinion this won't happen" is not the definition of a logical fallacy.

You go on to say "don't even think about it even as a thought exercise."

Man will never fly. It is a logical contradiction. This atomic bomb will never go off, and I speak as an expert on explosives. Everything that can be invented has already been invented. Humans will never fly to the moon; it is impossible. There is a world market for maybe computers.

And what we have now is the end of development; there will never be anything better.

And therefore we can't even ask the question.

You are totally misunderstanding the problem.

Your implicit assumption here that it is possible for a person "to do whatever is necessary to obtain that basic living standard." But the question is: once AI becomes good enough that it can do every job cheaper than a human, how do humans survive?

You say "why should someone else work harder so that I don't have to?"-- but it's not another human that is working harder. It is a mechanism. And that mechanism is cheaper than you are.

And it's not that you don't "have" to. It's that work no longer exists for you to work at.

if, as you say, the truth is "if you don't work, you don't eat", what happens when there is no work to be had?

Nevertheless, hydrogen fuel is routine in spaceflight.

Propellant leaks are a problem to be dealt with in all fuel types; not just hydrogen.
Liquid oxygen: https://spacenews.com/propella...
Kerosene: https://spaceflightnow.com/202...
Methane: https://spaceflightnow.com/202...
Hydrazine: https://www.teslarati.com/spac...

OK, you make good points-- you can get the error down with multiple measurements. Outside my capabilities as an amateur, but I'll accept your assessment that it wouldn't be a problem with observations by a qualified celestial navigator.

Yeah? Name one.

At extremely low efficiency.

Back to electrolysis.

Not sure what your thinking is here. Hydrogen stages for rockets have been in routine use for well over sixty years. By now it's a well-developed technology.

But orbital boosters can afford liquid storage at -253C; they only need to store the liquid hydrogen for a few hours, and the cube-square law means that the 150 tons of hydrogen needed for a rocket takes a lot longer to boil off than a hundred kilograms in a car. Liquid hydrogen would be an absurd choice for a car.

The killer problem with hydrogen is that it is so hard to store. The density is low, so although it has high energy per unit mass, it has terrible energy per unit volume. High pressure tanks, low temperature tanks, storage as liquid, storage as adsorbed hydrogen on metal (typically platinum or palladium)-- all of these are unsatisfactory in one way or another for vehicles.

May be good for stationary applications, where you can afford huge tanks, but it's simply not a good choice for vehicles.

I think this point needs to be emphasized more. The fossil fuel (read: oil) industry really doesn't want a replacement for petroleum-powered cars; they make trillions of dollars selling oil. They want to push hydrogen vehicle research as a replacement for petroleum not because it's going to work, but because it's not going to work, and they don't want a solution that works.

I'm not sure why you say most people won't adopt electric. Batteries are well down the learning curve, and the electricity distribution system is well developed and even more widespread than the gasoline distribution system. We power all sorts of things with electricity; cars are just one more.

Am I missing something here? The earth rotates fifteen degrees per hour, which is a quarter of a degree per minute (of time). That comes to fifteen (angular) minutes in one time minute, or one nautical mile every 4 seconds.

Correction noted; thanks.

Pretty much all concrete uses aggregate. Fly ash is just one specific form of aggregate.

Using fly ash in concrete is not new, though. https://www.fhwa.dot.gov/pavem...

Only if you have a reliable clock as well. You can't measure longitude with just a sextant.
(and I'm dubious about getting longitude to within a nautical mile. That requires exquisite timing.)

Birds are very complex.

No, that's the way bibliographic citations work.

The way quotations work is, a quotation is the work of the person who wrote it.