Why You Can't Travel Back in Time and Kill Hitler. (SLio9) io9 takes on the Hitler's Time Travel Exemption Act trope, from a classic episode of The Twilight Zone to Desmond Warzel's Wikihistory. [more inside]
The concept of time as a way to measure the duration of events is not only deeply intuitive, it also plays an important role in our mathematical descriptions of physical systems. For instance, we define an object’s speed as its displacement per a given time. But some researchers theorize that this Newtonian idea of time as an absolute quantity that flows on its own, along with the idea that time is the fourth dimension of spacetime, are incorrect. They propose to replace these concepts of time with a view that corresponds more accurately to the physical world: time as a measure of the numerical order of change.
I will always have been back. The precise nature of time travel in the Terminator universe has been the subject of griping from philosophy-trained bloggers and whole anthologies by academic philosophers. Despite valiant attempts, including this thorough assessment from M. Joseph Young's exhaustive Temporal Anomalies in Time Travel Movies , there has never been a truly satisfying unraveling of the twisted Terminator continuity. The knot has now been cut.
Rules for Time Travelers [Spoiler? alert.]
These subjects still fascinate me after a lifetime of interest: faster-than-light speed, alternate time streams, parallel universes, time travel, antiparticles moving backward in time, time loops, and the recurring themes of paradox -- all serious but astonishing ideas of science. Something about them inspires infinite possibilities. Am I not alone?
Time Travel, or, the art of causing events after they've already happened. [requires java, more inside]