Given a bit string, is it possible to assign it an immutable time stamp that is verifiable as correct without assuming a (one or more) trusted time-stamping authority? A time-stamp is correct if it is within delta milliseconds of the creation of the (instance of the) bit string, for some fixed but small delta. The creation time of a bit string is chosen by its creator / owner (but it is immutable once stamped).
To start off the discussion, I suspect that there will be a need to connect to some sort of physical information source (a la atomic clocks, resistor noise, radioactive half-life etc.) and make some clever use of it.
If it is not possible, I would like an argument that exposes the fundamental barrier. If it is possible, I would like an exposition of the main idea and links to papers or patents for details.
I apologize if my question has a simple answer that my novice mind has missed.
Thank you for considering my question and I appreciate your spending any cycles on a stranger's query.
Update 1: When I say that the creator of the bit string may choose the timestamp, I mean that they can choose when to timestamp the bit string. If they decide to do so at some time t, then the bitstring must be time-stamped to show time t (within delta). It does not mean that the creator can choose any timestamp in the past or future. Such arbitrary stamping must be impossible in the scheme, of course.