If time travel was ever possible, then why hasn't someone from the future come back to visit us?
I've been dreaming about going back to the early 1960s and patching things up with one of my first loves, and then later buying some MicroSoft stock, and enjoying the Easy Life.
However, that got me thinking - if time travel ever became possible, then why hasn't someone from the future come back to warn us of impending catastrophe, in an effort to avoid mass loss of life or environmental disaster?
Would it even be ethical? A time traveller would in effect end up playing God and manipulating things and generally just messing up the natural evolution of things.