Making an "Earth sandwich" is a curious practice found in Generation A by Douglas Coupland which was originally proposed by Ze Frank:
"I’d taken a slice of boring white bread from its bakery bag and had slapped it onto a small patch of yellow sandy dirt. I was standing up to photograph the slice of bread using my mobile phone. Why would you have been doing this? I hear you wonder. Excellent question. I was making an “Earth sandwich.” What is an Earth sandwich? Fair enough. It’s when you use online maps to locate the exact opposite place on the planet from you, and then hook up with someone close to that place. Then, after you mathematically figure out exact opposite GPS coordinates to within a thumbnail’s radius, you put a slice of bread on that spot, then connect via cellphone and simultaneously snap photos: two slices of bread with a planet between them. It’s an Internet thing. You make the sandwich, you post it, and maybe someone somewhere will see it, and once they’ve seen it, you’ve created art. Bingo.
Why do I blog this? this sort of ludic practice automatically found its way to my list of locative-technologies-repurposed-for-other-aims. Perhaps some sort of new and extreme ritual from the 21st Century (definitely the kind of ideas that Coupland document/describe/invent). Let's wait for the iPhone app, I am pretty sure someone out there would be willing to develop it.
Such idea sounds weird but I am convinced there would be some curious possibilities in interaction design, a sort of long-distance location-awareness if you want. Much of the focus in human-computer interaction research and product development revolves around the notion that location-awareness makes sense at the urban level (or national). The granularity is generally low, A gets a message that B is nearby (neighborhood/in town) and acts accordingly.
However, the Earth sandwich practice/meme is interesting from the long-distance viewpoint. Are there situations (casual or professional) where it's pertinent to know where others are? Should the granularity be different than current mobile social software? I guess so although I don't really know a precise use case. Maybe diaspora and families spread across the globe may be curious about it.