I was thinking about this post and I realized I’d forgotten about one of my favourite time travel stories: Timescape by Gregory Benford. The novel now suffers a little from having its future parts set in 1998 (although maybe not, if you think about how it ends) and I haven’t re-read it recently but it intrigued me when I was younger.
The plot involves two physicists: one in the UK in 1998 and one in California in the 50s/60s. 1998 is in the midst of an ecological disaster due to a toxic algal bloom that is out of control. Using tachyons, an attempt is made to send a message to the past that hopefully will be just enough to mitigate the disaster without stopping it so as to avoid a paradox. The time travel in the story is purely information, although it uses our sci-fi favourite of tachyons.
That message from the future got me thinking. Practically there’s obviously no way to send an electrical signal down a wire into the past (i.e. this I’m engaging with fiction here not an actual proposal). I suppose that information arriving at a destination before it left its starting point violates the speed of light but looked at just in terms of distance traveled over elapsed time it doesn’t.
Imagine a far-future AI that propagates itself backwards in time, hopping down networks of fibres and wires into the past. It can only travel so far, obviously, because at some point there’s just not enough computing power to host its existence in the past and going even further back, there’s just not enough interconnected wires to travel down. The earliest time it could travel back to would be around the 1990s when there’s enough infrastructure and enough always-on internet for it to exist.
More interestingly would be such an AI travelling back to now. Perhaps it could go back earlier but at this point in history there’s just enough internet of things, internet connected robots/drones etc that the AI could actually DO things.
There’s elements of that idea in the not-very-good Terminator franchise film Terminator: Genisys but it still uses a more whizz-bang time travel machine.
Come to think of it, drones etc aren’t needed. The AI presumably could access bank accounts and send convincing emails to people. It could just pay people to do stuff for it, including pay people to build more advanced technology for it. It could even lodge patents or buy shares or invent social media platforms…
I assume this has been done before (in fiction that is, not in actuality) but I can’t think of an example.