If anti-gravity propulsion gets off the ground (pardon the pun) then size & weight suddenly becomes irrelevant and you can see todays seagoing cargo container ships & international travel drops in cost by 99%.
Colonizing space will become commonplace from that point on. Instead of costing $20,000 per pound to put an object in a 100 mile orbit it become $20 per pound!!
Then with the possibility of placing space based bombs in space then nowhere on earth is safe and warfare has to be re-written all over again!
Some have speculated or asserted flatly that ET's are not the only ones with
MOTHERSHIP SIZED CRAFT of a mile or 3 on an edge.
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