I travel in back in time... all the time.

Donnie Darko any one?

How do you know if black holes are lethal? Has any one ever been in one?

We cant judge space physics with the physics that we know.

Don't even get me started about event horizons.

Black holes exert a gravitational pull that tends to rip matter right off a orbiting star, spinning at such high speeds into the event horizon that a funnel of x-rays shoots out... yeah I think that makes them pretty lethal.

We all know what happens when you bend space time, though.

Well, space-time coordinate of one of those space-time manifold charts (covering the space-time manifold) is one object that you certainly can "travel" back and forth(remember Godel formal PDE's solution for Einstein equation ). However , what realy counts and play the role of the Newtonian time in general Einstein relativity is the unique proper-time of a given event !(this can not be back!). Note that still remains a problem to "adjust" colectivelly the proper time of several geodesics associated to the motion of several particles moving in the back ground of a given relativistic gravitational field (The twin paradox has not been fully understood !).Let me explain better : In the Einstein framework , one gives a certain energy-momentum configuration (the "Sun") (mathematically a tensor of rank two in relation to the Local dipheomorffism space-time manifold group) in the (tensorial bundle) of space-time manifold :a object from the beginning possesing solely a differentiable topological structure and after that (and if compatible with the manifold topology-Chern /Gauss theorem constraint, Riemann completeness ,etc..), one determines the topologically compatible local metric structure of the smooth space-time by means of the famous Einstein Equations.If everything is smooth from a geometrical point of view , one starts the prediction of the "falling" bodies trajectories in this gravitational field throught the solution of the Boundary-Value Sturm liouville like problem associated to the geodesics non linear equations (you should know the beginning and the final point of the falling body trajectory into the space-time ,not the initial point and its "initial velocity" as in Newton Equation).Now one can make further steps on the Einstein program by exchanging the mater-energy Einstein's source by boundary ad-hoc conditions simulating point sources -delta sources-(not dipheomorffism covariant) ,like the Schwartz-Schild solution for Einsteinian particle motions around the Sun), and thus leading to a rich mathematical universe ( astronomical and astrophysical/cosmological observable ?)