Doppelgängers

I see doubles of people quite often. Not all the time, just enough to notice it. It always catches me a bit off guard, to see someone who pings so many of the subtle cues we use to identify someone -- their walk, their smile, the way they move while talking -- show up in the wrong context. I rarely see a doppelgänger in the same city someone lives in.

In this case, walking down the street with Dante (pseydtonne) to get a used copy of Grevisse, we were passed by an older Kendra. Probably in her 30s, but the same hair, facial structure, body type, walk, and even the same glasses (from when she rarely wears glasses). The match was downright creepy, although the flawless French is rather dramatically off.

I've noticed I tend to see doubles in batches, so I expect more over the next few days. I had a run of them when I first moved back. It might be I will see many Indiana and Montreal doubles while at StrowlerCon next weekend.

Greater and Lesser Infinities [Ask the Interweb Brain]

A question for my math-geek readers: are there infinities of differing sizes? I remember being quite certain there were at some point, but I am quite sure I am mistaken as to why. (I remember someone telling me that despite the intuitive obviousness of 0-infinity being smaller than 1-infinity, the truth is those are the same size.)

So, without necessarily trying to explain why in great detail, can someone confirm whether there are infinities of different sizes?