“They argue that the most plausible use of such power is driving interstellar light sails. The amount of power involved would be sufficient to push a payload of a million tons, or about 20 times the largest cruise ships on Earth.
“That’s big enough to carry living passengers across interstellar or even intergalactic distances,” added Lingam.
To power a light sail, the transmitter would need to focus a beam on it continuously. Observers on Earth would see a brief flash because the sail and its host planet, star and galaxy are all moving relative to us. As a result, the beam sweeps across the sky and only points in our direction for a moment. ”
(appended because the only SETI post i remembered putting up....)
Could fast radio bursts be powering alien probes?
paper https://arxiv.org/abs/1701.01109
https://phys.org/news/2017-03-fast-radio-powering-alien-probes.html
“They argue that the most plausible use of such power is driving interstellar light sails. The amount of power involved would be sufficient to push a payload of a million tons, or about 20 times the largest cruise ships on Earth.
“That’s big enough to carry living passengers across interstellar or even intergalactic distances,” added Lingam.
To power a light sail, the transmitter would need to focus a beam on it continuously. Observers on Earth would see a brief flash because the sail and its host planet, star and galaxy are all moving relative to us. As a result, the beam sweeps across the sky and only points in our direction for a moment. ”
(appended because the only SETI post i remembered putting up....)
and Centuri Dreams does an in depth look...
http://www.centauri-dreams.org/?p=37307