A device known as the EM Drive is in early proof of concept testing, with the space agencies of the US, China, and Europe busily at work. A form of thruster that relies on microwaves without a reaction mass such as that provided by chemical fuel, the EM Drive -- if valid -- could make a trip to the Moon a matter of hours and Mars a matter of a week or two.
The much derided concept of Cold Fusion has re-emerged under the name Low Energy Nuclear Reactions (LENR), with a clutch of avid experimenters and inventors claiming positive test results, attracting support from investors and institutions, and getting patents filed and approved. If successful in yielding a practical technology, LENR would provide an abundance of cheap, clean, reliable energy capable of replacing most forms of heat and electric power generation and the internal combustion engines used in transportation.
More speculatively, Mexican theoretical physicist Miguel Alcubierre has proposed that negative energy could be used to warp spacetime around a spacecraft so as to make faster than light travel possible. As he and other physicists have refined his calculations, the "Alcubierre Drive" has gone from virtual science fiction to something that might one day be within reach.
These developments have several things in common: serious interest by NASA; a grounding in current theoretical physics, even if on contested reasoning that would lead to major revisions if experimental verification is accepted by the physics community; and, I would bet, most of those actively involved in the work believe that UFOs are real and of alien origin.
That EM drive took (and still takes) physicists by surprise, and its design must be terribly frustrating, because it doesn't leave a way back out to some kind of acceptable explanation, outside of a purely QM model. :^) It's an absurd situation, not least because there appears to be no plan to test it in space. A test bed should be orbited, pronto! :^) Gwynne Shotwell of SpaceX stated not long ago that they're doing work on nuclear propulsion, a system that has never shown practical feasibility and was abandoned in the 1970s (it can't get itself off the ground, it only works in space). Seems like EM drives (radio frequency resonant cavity thrusters) would be cheaper and better and easier to recycle after each use, but hey, the mighty Elon has spoken, the smoke has gone up on each side of his face and everything. :^D