[ben_w]

I think they'd be very helpful for anything involving an airless body, e.g the moon. At least as a bootstrap — when we get going, we might want to do megastructure-scale electromagnets so humans can survive the gee-forces.

(We can't do megastructure-scale electromagnets right now: while they would work and China has a big enough industrial base, nobody on Earth is in the mood for anyone talking about building a 1000km diameter electromagnet significantly stronger than Earth's magnetic field).

[henearkr]

Yes, and also there is a limit to what we accelerate within Earth's atmosphere, as it tends to burn up from friction.

So yes, the simpler machines on Earth are mainly useful at first as a bootstrap, and after that it would rather be from the Moon or Mars as a hub, with huge electromagnetic railguns.

Between Earth and low orbit, maybe some version of a space elevator could finally see the light?

If we follow this kind of blueprints, prioritizing electromagnetic tech instead of fossil fuels, we can successfully bootstrap some amount of space-based industry without trashing too much Earth's liveability.