Nothing is impossible…
“Kaku deals with such far-fetched ideas as invisibility and teleportation in a completely scientific manner. He divides impossibility into three classes: Class 1 for concepts our present technology can’t make manifest, but which don’t actually violate any known physical laws; Class 2 for concepts beyond our technology that also challenge our interpretation of those laws; Class 3 for concepts that outright defy known physical laws and would demand huge changes in our understanding of how the universe works.
Surprisingly, the third section is the shortest. Only two of Kaku’s topics are impossible in this sense. Perpetual-motion machines and precognition, the staple of storefront psychics, come much closer to true impossibility than constructs familiar to us through cinematic special-effects, namely Class 2’s time travel, faster-than-light spaceships, and parallel universes.”
