My favorite theory is that there's been at least one Bracewell probe in our solar system since the 1920s. https://en.wikipedia.org/wiki/Bracewell_probe https:/

My favorite theory is that there's been at least one Bracewell probe in our solar system since the 1920s. https://en.wikipedia.org/wiki/Bracewell_probe https://en.wikipedia.org/wiki/Bracewell_probe https://en.wikipedia.org/wiki/Long_delayed_echo https://en.wikipedia.org/wiki/Long_delayed_echo http://folk.uio.no/sverre/LDE/ http://folk.uio.no/sverre/LDE/