Engineering makes it possible. Nothing makes it happen.
Wondering what it is??.......well, its something you would never have heard or seen before.
The idea is based on the simple Archimedes principle. A large spherical structure is build and the air inside is evacuated i.e a vacuum is created. The structure is designed such that the weight of the air displaced is greater than the weight of the structure.
So it starts floating in air when evacuated.
Conventional blimps use hydrogen mixture to create lift, making them dangerous and expensive to maintain. We on the other hand use vacuum, making it much safer and much cheaper.