Humans are getting closer to being able to manipulate gravity, yet the question is can we trust mankind and their war mongering tendencies? Hell I don’t; how about you? But as I speak I have a brother who is a US Marine, with a flight contract, who is temporarily re-assigned to guard the Syrian-Iraq Border. Being able to manipulate gravity might come in handy, lifting a car off the ground, which has a suicide car bomber in it, then turning off the machine and letting it fall to the ground. In fact the idea is so tempting that surely it will be used in human conflict; that is to say the killing of our own species. Unfortunately it is for that reason that such a wonder technology should be well guarded and agreed upon in advance to how it will be used.
Once such a technology exists you can image its destructive power in the wrong hands such as an International Terrorist picking up a bus 100-feet in the air and letting it drop if their demands are not met? Or a nation which wishes to serve its political will taking a giant rock up to 100,000 and towing it over to a neighboring nation state for which they have a disagreement? Those are not such pretty thoughts, yet ones which should be consider as we advance our technologies to be used in aircraft, transportation building.
If you consider building a building without using dangerous cranes or saving people in a burning building by lowering them safely to Earth you can see the advantages. No more traffic, cars can fly. No in-efficient aircraft as they fly to where they want to go and lower into place, saving fuel to climb and land. No more worries about launching satellites or putting colonies in orbit, as they could float up effortlessly and easier than launching a balloon. Mining the moon would be easy too or snatching an asteroid and putting it into geo-sync for needed materials. We could launch a space ship the size of an Aircraft Carrier and go visit our neighbors around the solar system and discover all that we quest to learn. Leaning of other worlds and life of all types.
Here on Earth we could pick up large ice cubs and put them in drought stricken or dried up lakes to provide water for our people and those areas of the world, which have surpassed their water supplies due to population increases. The potential for such technologies can save fuel, save pollution, provide water, help with materials we need and make transportation safer. Now then we must also be considering it unfortunate uses due to the fact that humans are still a warring species and they may use such technologies for things, which are not so noble. Think on this.