And how do you detect ansible communications?
You're on the right track. You may not know this : your body and the world around you are fermions(electrons, protons, neutrons)which are WAVES as well as particles; originally called MATTER WAVES by Louis DeBroglie, the french physicist who first proposed the possibility of their existence(circa 1919). They were discovered in 1926 at the Bell Labs and thus E=mc^2=hw where h is planck's constant and w is the (matter) wave number, thus the foundation for Quantum Mechanics. Almost immediately though matter waves threw the relativists into the "ballistic" mode : De Broglie's formula for the speed of a matter wave crest is U = c^2/v, ie, they travel FASTER than the speed of light(c). So they tried to cover up this obvious embassassment with the group/phase cover story, and relegate matter waves to the "crazy aunt alice" category, referring to them only obliquely as "the wave function", hoping you'll think that means EM waves that travel at c. Is c^2 an area(mass as in mv^2/2)or line(Momentum as in mv)? If it's LINE then c^2 = 9 x 10^16 kps or covering one light year in 105 seconds(earth normal). Thus c^2/v means the overall GLOBAL(vehicle)velocity is 9 x 10^16 kps and the LOCAL(internal)velocity is 0 kps(15 minutes round trip to Alpha Centauri). Analog : completely at rest on a 800 kph jet. SETI can waste away their lives looking, but they are looking in the wrong place : Book of Revelation : and there was a WAR in heaven. Would it ever DAWN on them that warfare isn't confined to just we "apes with guns" as intelligent aliens refer to us? C-signal "slop" can be fatal in warfare, yes? Now, wanna know how "time" and "gravity" tie into matter waves?