I forgot to mention who this Bob Lazar guy is, so I had to do this as it would be a shame not to.

This man is a physicist who claims he worked at S4, which according to Lazar is a secret facility in Area 51. (He was talking about Area 51 before it was officially admitted that this place exists.) He stated on tape that a bunch of scientists including himself were hired to reverse engineer saucer-shaped aircraft. He said that the materials and techniques used to build those things were not known to mankind which is why they were hired to reverse engineer; the government didn't know how those things were built.

He also stated that the 'engine' was basically comprised of thermonuclear reactors (which were 100% efficient in violation of the first law of thermodynamics) and gravity wave generators (he said that before the existence of gravity waves was known). The reactors would power the gravity wave generators which would then produce gravity waves in order to distort spacetime and travel huge distances instantly, making intergalactic travel possible. He also talked about ununpentium being used by the reactors as a source of energy for such craft. The guy made some crazy claims without a doubt, however he sounds so very credible! It's weird!