A micro short story of Ted Chiang: http://www.concatenation.org/futures/whatsexpected.pdf Given the assumptions in the EPverse, this technology might be just around the corner. There are already QE communications, and together with relativistic motion you can set up a negative delay loop. The message in the story might be a warning from a near-future Firewall trying to stave off a cognitive disaster... ...or just prevent the atemporal hyperintelligence that is now dominating the world of one year ahead from deep in the future from reaching much further. As long as the bandwidth from the future back to the present is low, such entities can't do much harm. But they are most interested in safeguarding the invention and eventual spread of negative delay devices.