Clone Of The Long Now

This is in a sense a coffin, in that it preserves your remains.

At the moment of your death, a diploid nucleus is removed from your body and placed in a microscopic chamber filled with a droplet of liquid nitrogen and surrounded by a Peltier device which cools the very small chamber to seventy Kelvin or so. The device includes two high temperature superconductors, one with a transition temperature somewhat above the boiling point of liquid nitrogen (YBCO is superconductive below ninety, SmFeAs(O,F) below fifty-five) arranged so that only if the first one is superconductive but the second isn't, then the current flows to the Peltier device (i.e. logic gates and a transistor or something). All of this is a solid mass with no moving parts and creep is reduced to a minimum.

Power is provided - how? I don't know. I have various thoughts, involving varying temperatures during the day, lunar tides, continental drift movements.

A funeral is held somewhere a long way from subduction zones, faults and hot spots. A granite memorial is erected with deeply incised Pioneer-style Rosetta stone instructions and an explanation of what to do with the remains if found. This is replicated on a platinum or other durable plate within the chamber.

The human race becomes extinct, ice ages come and go, sea levels rise and fall, asteroids hit the planet and all the usual shenanigans you get through geological time.

Finally, many millions of years from now, an extraterrestrial civilisation finds the monument or a new tool-using species evolves. If there are still primates on the planet, the nucleus can be desfrosted, placed within an ovum and your identical twin is reborn geological epochs after your death and the death of your species.