We apply physics and mechanics and electrical engineering, and it can transform someone's life, from one day being able to hear nothing to then being able to hear voices and people and sounds and, really having a transformational impact.
The waves were predicted as part of Einstein's General Theory of Relativity nearly 100 years ago. It was the theory of the physics behind the workings of our world and the universe.
Thirdly, I would never have thought it possible that another human being could occupy my waking and sleeping thoughts to the exclusion of almost everything else.