Use rotating beam of light to bend timespace and travel in time
Circulate laser beams to create enough gravity to replicate the frame dragging of a rotating black hole, and create a minute time loop. Use it to send information to the past.
The suggested size of the time loop would be on the order of size of human-hair, and the use of the number of lasers on the order of 10 thousand.
Source: video -- about this idea of Ron Mallett, Prof. of Physics, University of Connecticut. (alt link)