It turns out that once you go looking for stories about doppelgangers, you can't stop finding them--it starts to seem like it's statistically unlikely that you won't bilocate yourself at some point.

Goethe saw himself once from eight years in the future, wearing a fancy suit. Goethe also recommended treating people as you would like them to be, and maybe that comes from this. If you see yourself time traveling back from the future wearing a fancy suit, what's to stop you from moving forward through time into that same fancy suit? Doppelgangers are usually harbingers of death or other unpleasantness, but maybe sometimes they're just from a future closer than others.

It turns out that you can make a brain think it's seeing a doppelganger by stimulating the temporoparietal junction, which is the spot where your brain mostly distinguishes your self. Scientists stimulated a woman's brain right there at the end of the Sylvian fissure and she felt another presence there mimicking her posture. Things got even creepier as the stimulation got more intense--too creepy for the experiment to continue. It could be that the temporoparietal junction is responsible for our sense of self, I suppose, but I find it just as likely that that's where our time travel switch is located.

I flew to Florida through strangely quiet columns of clouds, each its own contained thunderstorm. Each was unmoving and silent and seemed to be hiding an armchair for giants on just the other side. In between them we flew over a rainbow, which seemed just as distant as they do from below. By the time I pointed it out it was gone.

Coming home I found myself unexpectedly trapped nowhere near a window, each jolt of the plane magnified by not knowing just where the ground was.