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I am not versed in general relativity but I see a problem with your scheme. Let us take the ensemble of distant stars as our inertial frame. Whenever a body has acceleration $\textbf{a}$ w.r.t. inertial frame it experiences an inertial force equal to $\textbf{F}_{inertial}=-m\textbf{a}$, where $m$ is body's mass. Now suppose that the large mass $M$ in your ...

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I think your right. Due to equivalence principle, to the free-falling body it will seem like it has no acceleration, as opposed to a body standing on ground which is equivalent to the ground pushing the body so that it will accelerate upward, and hence experience the normal force from the ground. Because the acceleration due to gravity will depend only on ...

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Primary question: This is very similar to the old question of what would happen if you fell into a black hole. You are correct that you wouldn't feel the acceleration due to gravity per se, but you'd still need to worry about tidal forces. These have complicated geometric dependence - they're negligible near the center of a planar mass $M$, and for a ...

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It's unclear what you mean by "nuclear engine", but the main similar notion is a nuclear thermal rocket. Although it derives its energy from nuclear reactions, it uses this to heat gas (usually hydrogen) to very high velocity for propulsion. There is still matter being expelled. More common in space travel is the radioactive thermal generator, which uses ...

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Every action has an equal and opposite reaction. So to propel ourselves "forwards" we must propel something else backwards. In ground vehicles we push against the ground. Since the ground is practically in immovable object this is very efficient. In airplanes we propel outselves forward by propelling air (and a small ammount of combustion products) ...

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