Apropos of this post, I read this story a few days ago and have been thinking about time travel ever since. If I understand the article correctly (which, after several rereadings, I am pretty sure I do not), the theory is not dissimilar to what Superman was up to when he flew circularly, counter-orbitwise, around the earth to turn back time and undo both the earthquake and Lois Lane's demise. How funny if that turns out to be the key to time travel - way to forecast, DC Comics! But for my time-traveling money, the time travel hypothesized in the article has two serious drawbacks: its availability only to "distant future generations" and its inability to go further back in time than when it was created. That's all well and good for those distant future generations, but how does it help me visit ancient Egypt? And I'm not sure whether it's depressing or encouraging to imagine distant future generations thinking of the early 21st century as analogous in any way to the world we now consider ancient.