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Worldbuilding

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    $\begingroup$ This makes sense to me, but IMO it could be worded a bit nicer. $\endgroup$
    – Ekadh Singh - Reinstate Monica
    Commented Sep 20, 2021 at 1:06
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    $\begingroup$ Re: "once the gravity beneath your satellite is neutralised, what keeps your satellite in its orbit?", there's not actually a problem with that. Either the effect is one way (the satellite emits a 0.5 g field but is attracted by other gravity fields as if it only had the mass of the satellite, in which case it orbits as a normal satellite would) or it's bi-directional (the satellite both emits and is gravitated upon as if it had enough mass to possess a 0.5 g gravitational field and orbits as a moon would). $\endgroup$
    – GrumpyYoungMan
    Commented Sep 20, 2021 at 3:14
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    $\begingroup$ @GrumpyYoungMan if you are in, eg. low earth orbit and the local gravitational field suddenly drops by half a G, you're now travelling at over escape velocity. If the satellite is now a gravity source (rather than reducing or nullifying it) it will fall towards the earth because it will no longer be travelling at an orbital velocity sufficient to keep it up given the strength of the local gravitational field. This is why you need magic, in order to handwave away all these issues. $\endgroup$
    – Starfish Prime
    Commented Sep 20, 2021 at 10:10
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    $\begingroup$ I think the problem about neutralising the gravity beneath an orbiting satellite would be better framed as: If you need a powerful rocket to keep the satellite in orbit, is that going to take more energy than lifting whatever you're lifting without altering gravity? It might be that keeping the satellite in place becomes difficult and expensive, but the whole thing still works out cheaper overall (ignoring your point about conservation of energy, of course) $\endgroup$
    – SpoonMeiser
    Commented Sep 20, 2021 at 11:42
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    $\begingroup$ Turning gravity off reminds me of this Asimov gem en.wikipedia.org/wiki/The_Billiard_Ball $\endgroup$
    – SeanR
    Commented Sep 20, 2021 at 12:49