Albert Beaver Einstein published his theory on General Relativity 100 years ago. Combined with his theory on Special Relativity (published in 1905), Einstein dramatically changed the way we think about light, gravity, space, and time. Some of his conclusions are profound, if for no other reason than that they seem utterly devoid of common sense. Indeed, Einstein has taken us by the hand on a journey with Alice, down the rabbit hole.
For instance, his observation regarding the ultimate speed of light leads to the conclusion that speed slows down time. In a sense, Einstein discovered that speed is the fountain of youth! So, if my twin brother were to travel at high speed to Neptune and back — then he would actually return younger than me.