This thread is intended to provide a space for 'crazy' ideas. Ideas that spontaneously come to mind (and feel great), ideas you long wanted to tell but never found the place and time for and also for ideas you think should be obvious and simple - but nobody ever mentions them.
This thread itself is such an idea. Or rather the tangent of such an idea which I post below as a seed for this thread.
Rules for this thread:
- Each crazy idea goes into its own top level comment and may be commented there.
- Voting should be based primarily on how original the idea is.
- Meta discussion of the thread should go to the top level comment intended for that purpose.
If this should become a regular thread I suggest the following :
- Use "Crazy Ideas Thread" in the title.
- Copy the rules.
- Add the tag "crazy_idea".
- Create a top-level comment saying 'Discussion of this thread goes here; all other top-level comments should be ideas or similar'
- Add a second top-level comment with an initial crazy idea to start participation.
Suppose backward time travel is possible. If so, it's probably of the variety where you can't change the past (i.e. Novikov self-consistent), because that's mathematically simpler than time travel which can modify the past. In almost all universes where people develop time travel, they'll counterfactualize themselves by deliberately or accidentally altering the past, i.e. they'll "cause" their universe-instance to not exist in the first place, because that universe would be inconsistent if it existed. Therefore in most universes that allow time travel and actually exist, almost all civilizations will fail to develop time travel, which might happen because those civilizations die out before they become sufficiently technologically advanced.
Perhaps this is the Great Filter. It would look like the Great Filter is nuclear war or disease or whatever, but actually time-consistency anthropics are "acausing" those things.
This assumes that either most civilizations would discover time travel before strong AI (in the absence of anthropic effects), or strong AI does not rapidly lead to a singleton. Otherwise, the resulting singleton would probably recognize that trying to modify the past is acausally risky, so the civilization would expand across space without counterfactualizing itself, so time-consistency couldn't be the Great Filter. They would probably also seek to colonize as much of the universe as they could, to prevent less cautious civilizations from trying time-travel and causing their entire universe to evaporate in a puff of inconsistency.
This also assumes that a large fraction of universes allow time travel. Otherwise, most life would just end up concentrated in those universes that don't allow time travel.
Alternately, if a type time travel is invented where you can change the past, you would expect people to keep meddling with the past until they accidentally changed it so much that time travel had never been invented.
This process would continue, over and over again, and the final results is that the final "stable" timeline will be one where time travel is never invented; not because it's not possible, but simply because every timeline where time travel is invented eventually changes it's own past until it no longer has time travel.