# Far future: how long will engraved stainless steel tablets last? And why?

Last night I read this fascinating Wikipedia article, "Timeline of the Far Future":

https://en.wikipedia.org/wiki/Timeline_of_the_far_future

Some human creations have very long but ultimately finite lives. For example:

• The Pioneer 10 Plaque will be unreadable in 800,000-8 million years due to interstellar erosion (which apparently is poorly understood).
• The Voyager Golden Records are expected to be unintelligible in 1 billion years.
• The "Memory of Mankind" stoneware will probably be unusable in 100,000 years

Etc.

Let me add one more thing to the list, but preface it by saying I'm not a Scientologist and am aware they're a destructive cult and have bizarre beliefs.

However, I recently finished Janet Reitman's "Inside Scientology" and it discussed the fact that the Church of Scientology has taken their founder's work and engraved them on steel tablets and placed in them in titanium capsules (with with inert gas I believe). These capsules are buried in various mountain bases in the continental US.

Their purpose is that his words will live forever...more likely, the Church will eventually fold and they'll go to some future foreclosure tax auction. But if one of those capsules did remain in its buried vault, how long would it last?

The Memory of Mankind project seems to have similar (though actually noble...) goals, but I was surprised to see a limitation of 100,000 years. Would engraved stainless steel last longer than MOM's engraved ceramics?

And what drives the destruction? I can understand when something is in the hostile region of deep space like Pioneer 10, and obviously some day when the sun goes red giant, these things may be destroyed, but if either MOM or Scientology's silly texts are sitting in a vault in a mountain, what is there to destroy them?

• Some interesting points. Note that $4.3\times 10^9$ years is about the age of the Earth, so plate tectonics is not needed to explain why we don't see older rocks. Indeed, many of the Earthly (as opposed to meteorite) samples are just under the assumed age of the Earth. – Selene Routley Oct 11 '17 at 1:32