It’s neat to think of time capsules as time travel. We know of at least two possible methods of time travel into the future for human beings, namely cryogenics

It’s neat to think of time capsules as time travel. We know of at least two possible methods of time travel into the future for human beings, namely cryogenics and rocket travel at some appreciable percentage of the speed of light. Time capsules are a form of time travel for our thoughts and ideas. I wonder if there might be methods for creating personal time capsules that don’t depend on a historical record of their existence. For instance could you determine the rate of erosion of a particular river, then drill a hole into the rock and encase a bottle-sized time capsule within it. At some point centuries hence when the rock wears down enough, the capsule would become visible or dislodged, perhaps to be found downstream.