On 22 February 2018 at 05:18, Jeff Zeitlin <xxxxxx@freelancetraveller.com> wrote:

Canonically, TL9 is essentially distinguished by the achievement of gravity
control technology, which (also canonically) includes both attractive and
repulsive control. This gives us floating cities (or at least floating
Imperial Palaces), air/rafts, GCarriers, et multae ceterae.

As a side note to your question, I'm not sure I'd allow floating cities *at* TL9 (i.e. as soon as it became available), air/rafts, Gcarriers, yes. Then maybe a small palace at TL10, floating cities a bit later. Not sure it's canonical but it makes sense to me.

Anyway, to your point although I suspect it's well above my pay grade...

Arguendo, assume that the laws of physics do not admit of repulsive
gravitational manipulation. No floating palaces, no air/rafts or GCarriers
as we know them. You get attractive gravitational manipulation, and some
ability to do it directionally, and with controllable range. 'Blocking'
isn't possible, so no "anti-gravity screens (or walls)".

What are the effects on planetary construction,

Planetary construction? When did that come in in Traveller? I've always thought Magrathea style technology would be TL20+

ships, vehicles, und so
weiter?

Presumably not being allowed repulsion would preclude train type vehicles using that as their technology, but could you come up with something, maybe along the lines of a maglev but upside down. You have an overhead rail which the train is attracted upwards to, but doesn't quite stick to and is jimmied to allow forward or reverse motion. Or is that blindlingly obvious? Presumably you could have individual cars or trams etc that did the same.

I think my bigger question might be, is the floating city 'repulsed' from the ground, or 'attracted' to heights by negating gravity? I thought it was the latter. But the other question is why do you want to do away with floating cities anyway.... they're so coool!

Ships presumably would still allowed artificial gravity as an attractive force and you could still play gravpong with plates in the deckheads as well as decks. If this can be done small enough and directionally enough, would you get a weapon that would literally floor someone? (Not repulsing them but essentially dragging them towards you but too quickly to avoid falling over.)

Don't know if these thoughts help.

But you've reminded me of an email I meant to send this morning... :-)