Terwin

Either you have: a) a flashlight that applies less pressure than direct sunlight on a white piece of paper or b) you have the main component of a perpetual motion machine In either case, you have not really given enough information about your magi-tech tool to answer any of your questions. If anything, I would expect your force-gun to have a range of perhaps a couple cm under water as it uses all of its force to push against the water in question(which would then pull you along with the generated flow) Even in air, I would expect the range to be less than a meter, as it pushes against the air(which has mass, and is thus a valid target by your description), so in-short you have a very high-tech fan/propeller blade that breaks the 3rd law of motion(action/reaction), making it much less useful for providing propulsion(unless you are blowing air into a sail).

How quickly can you get > 3 million of these heater/tank units to New York during a power outage? How long will those tanks last when most of those users have little idea how this thing works? And those will do nothing to prevent pipes from bursting unless you have one for every kitchen and bathroom in the city in addition to the > 3M needed for 1/residence

Are you willing to shut off your heating for a week or two in the middle of winter in sub-freezing temperatures? (no wind, minimal solar) How about turning off your cooling systems in the middle of summer when it is consistently 110+f during the day and 90+f at night for a week or more? (possibly some wind, too hot for solar) Would you be be ok eating meat from a freezer that has been shut off an unknown number of times for unknown durations before it even gets to your door? Without very stringent laws and a significant loss of quality of life(and lives in general) you will not get demand varying to meet supply any more than we already get with variable pricing. Variable power supplies may be a viable supplement when your have an adjustable supply that has a capped annual output(like hydro that no longer gets enough annual in-flow to handle annual demand), but they can never be more than a supplement to support short-falls in the existing base power. Grid-scale energy storage is completely unrealistic for anything beyond power smoothing and allowing for plant ramp-up time, both of which are measured in seconds or minutes, not days and weeks like you would need for covering variable power supplies.

Are you suggesting that zero-boiloff technology has advanced to the point that we can store an unpowered, liquid hydrogen fueled vehicle in an unair-conditioned garage in a southern state for days without a need to vent? That should make storing cryogenic hydrogen all the way to Mars pretty simple in comparison.

Nuclear plants Are cost-prohibitive in the US because the department of energy is both authorized and encouraged to tighten safety requirements any time nuclear becomes cost-competitive with any other power generation system in common use(like when fuel prices spike for existing plants of other types) And they cling to their no-threshold metrics in spite of the substantial and confirmed evidence against them. If the department regulating nuclear power were not incentivized to block future development, it would be much more affordable (but that could undermine the stock value of important donors) CO2 and nitrogen are frozen at MRI temperatures. You need something that can get much colder than those can. You suggest that a hydrogen fueled motorway is not full of ignition sources? How about the enclosed garage where the car is stored over night or while the family is away on holiday? Does hydrogen have a strong scent like spilled petrol does to warn away from turning on the lights?

A few points: Renewables are not 'free once set up' and you would need grid-scale storage of hydrogen. Hydrogen storage is notoriously difficult even for short-term usage(like single-use rockets) Hydrogen quickly destroys any container that holds it through embrittlelment, and is hard to store long-term because it can slip between the atoms of the storage container. Hydrogen is highly flammable and can explode when mixed with air. In short, even using 'cheap' petroleum sourced hydrogen is completely untenable for consumer use. Hydrogen is a (very bad) storage medium, not an energy source. Even in rocketry, hydrogen is only used by the government and only because it is easier to throw money at the problem instead of finding other solutions. Evidence: MRI machines could be cooled by hydrogen just as well as very expensive helium, but hydrogen just causes too many problems to be cost-effective.

That is only if you go slow.(like 0.1c or less) Sort of like going over a speed bump at 2mph vs 60mph. The first you might barely notice, and the second could break your axle or your spine. Every body is at the bottom of a well, and if you have no inertial dampeners, then zipping past ceres at near-light speeds might break bones and break off pieces of your ship just due to the rapidly shifting gravity. Fly past a real planet and you can get everyone smeared against the starboard wall of their current room as the ship gets jerks to port because of the the 'gravity pot-hole' created by the planet. And if any other ship uses the same sort of drive, then they might well fling your ship into a star anyway, just because you are unanchored to local space while they are moving in a different direction..

Except the corporations with the most money to spend on AI will not want any of those pesky ethics or morals you mentioned.

The resources themselves never run out, but you can only harvest it so quickly based on how rich it is. Think of it as having a limited number of useful mining sites in the biome for that resource. The mines never run dry, but you can only build so many of them before you run out of veins.

Don't forget Sturgeon's law. Only the best of the best survives the dust-bin of history.

Without magical inertial dampening(probably an instant reverse gravity effect to counter any impacts, or just a low-level warp effect that dampens inertia directly), you risk having your entire crew being turned to goo any time you pass too close to a nebula at warp speed(or pass through any other significant change in the density of the interstellar medium). This sort of effect would be needed for any sort of super-luminal travel that passes through real space.

99.86% of the mass of our solar system is in the sun. The remaining 0.14% is orbiting the sun using the net orbital momentum of the starting material. When you only need to orbit 0.14% and you are pulling in particles from thousands of au away, a tiny amount of initial momentum is all you really need. Light pressure from distant stars may well be all it takes. Anything not in the orbital disk will collide with something in the disk and either move closer to the disk, or closer to the sun/escape velocity. Only things with very few chances to interact with the orbital disk will be notably eccentric (like long period commets), as many interactions (collisions or gravitational interactions) will get them lined up with the disk.

When a photon hits a particle, the particle can absorb the photon, thus increasing the energy level of the particle(such as an electron). If a particle is in an excited state(such has having recently absorbed a photon), then it can emit a new photon as it returns to a lower energy state. (this new photon will often be at a different frequency depending on the particle that emitted it) If you are talking about a photon 'disappearing' during something like the double-slit experiment, then it does not disappear, it was never there, that location was just inside the probability area where the photon might have been.

True, any sorts of details that might help non-US interests in developing similar rocket capabilities might be illegal for SpaceX to share. Might be why there are lots of FOA requests and it has not been released: the US gov says 'No'

Kind of makes you wonder if 'dark energy' is just the consequence of a plank-length type limitation on gravitational waves, limiting the effect of gravity at longer ranges much like the plank length prevents the 'ultraviolet catastrophe' with very short EM waves. Then that might suggest that 'dark matter' is a consequence of something akin to emission spectra, but with a spectra specific to our galaxy/universal constants/etc. Then again, that may not provide any testable predictions, making it a rather useless interpretation.