Its Alcubierre drive space ships coming out of warp and obliterating their destinations.

Think of it metaphorically. This approach moves the weight of the heavy energy storage (gasoline or hydrogen or batteries, etc.) from the moving vehicle to the ground. Then, the energy to move the vehicle is conveyed to the vehicle with massless, essentially lossless photons/electrons/radio waves, much in the same way that an electric train is powered.
Super idea.

I have always wondered, when reading of "sails" being pushed through space by solar wind, laser beams, and now a radio transmitter, how do the occupants get back home again. Haven't puzzeled out how they turn around, or engineer a reverse gear.

Maybe we are looking as exhaust from highly time dilated space ships, the actual exhaust being in the gamma ray region.

Perhaps it could be some SETI signals that are being broadcast out in the universe in the hope that some "extraterrestrial" intelligence would find it. No different than what we are doing.

Oh deary me, immature speculation written large...just where is scientific impartiality...

The best possible way to beam light is with something like a laser, but even there the spot size far from the source depends on the diameter of the objective lens. This is why the lasers used to measure distance to the moon have their beams expanded using a telescope in reverse. But even with a planet sized "lens" the range where most of the power gets to the spacecraft would be limited. After that the efficiency would be poor.

Given that they are 3 billion years old, perhaps past tense throughout the article, would be appropriate. Modern electronic communication transmissions also use compressed information pulses. So maybe if these pulses were 'uncompressed' it may be found that they contain information, that is, if they are not purely natural events, like pulsars.

Random wideband em radiation in any form is to be expected from an Electric Universe. All visible (and many invisible) phenomena in space can be explained by plasma discharge. Nothing else, except an electricity supply is needed. Who the heck needs gravity to make x-rays, radio, UV and of course light? What a waste of space is the Standard Model, so far!

It would make sense. There is no faster-than-light drive. Einstein was right. The only way to go interstellar is using light sails as proposed by Stephen Hawking, et al. Multiple civilizations come to the same conclusion and build the same kind of craft. We see their gasp at immortality as the civilizations flash into existence, reach their zenith and decay into extinction. This happens on millions and billions of worlds and this is the result. I guess we should get building one...