Maybe They Left For Earth In 1815

Interesting, and if they detected the Industrial Revolution we might catch the departure ceremonies of their flight here:

According to a paper Siemion authored last fall, a five-year campaign by the first phase of the SKA could allow scientists to survey more than 10,000 stars. When completed, the SKA could detect signals as faint as those emitted by aircraft radars on Earth from every star within almost 200 light-years.

200 lightyears makes our tiny human window into our 20B LY observable universe less tiny, but the coefficients in the Drake equation may be larger than is generally thought because the power of the weak anthropic principle means technological civilization can be dependent on an arbitrarily unlikely series of events (given a universe of infinite size), and thus technological civilizations could find themselves looking around for signs of others that may also have spontaneously arisen nearby, but not finding any such events within their lightcone because such events might only happen in a very small proportion of such (finite) lightcones.   And if as seems increasingly likely we live in a “multiverse” of constantly branching quantum probabilities, the abundance of intelligence may be minimized in much the same way that entropy is conserved (because events that increase entropy are just vastly more likely than events that decrease entropy) — the number of paths leading to parallel, simultaneous intelligent civilizations must be a function of how arbitrarily unlikely a single such civilization is to arise during a given period of time and space, which is something we can’t yet know today — but this will take us a tiny step closer.