I stumbled onto a great, succinct source of relevant information on Ukraine. The Visual Capitalist. Their visual representations of many subjects are quite good.
This weekend I’m going to a tech conference for the first time in at least two years, maybe three. The Western Winter Workshop. Indian Wells is pretty nice this time of year.
I absolutely love the fact that a group of academics from Sweden and Penn State have done a serious mathematical analysis of the probable number of Dyson spheres in our galaxy. From the abstract:
Dyson spheres are hypothetical megastructures built by advanced extraterrestrial civilizations to harvest radiation energy from stars. Here, we combine optical data from Gaia DR2 with mid-infrared data from AllWISE to set the strongest upper limits to date on the prevalence of partial Dyson spheres within the Milky Way, based on their expected waste-heat signatures. Conservative upper limits are presented on the fraction of stars at 𝐺 ≤ 21 that may potentially host non-reflective Dyson spheres that absorb 1–90% of the bolometric luminosity of their host stars and emit thermal waste-heat in the 100–1000 K range. Based on a sample of ≈ 2.7 × 105 stars within 100 pc, we find that a fraction less than ≈ 2 × 10−5 could potentially host ∼ 300 K Dyson spheres at 90% completion. These limits become progressively weaker for less complete Dyson spheres due to increased confusion with naturally occurring sources of strong mid-infrared radiation, and also at larger distances, due to the detection limits of WISE. For the ∼ 2.9 × 108 stars within 5 kpc in our Milky Way sample, the corresponding upper limit on the fraction of stars that could potentially be ∼ 300 K Dyson spheres at 90% completion is 8 × 10−4.
Bottom line, there could be as many as 300,000 advanced civilizations in the Milky Way that have constructed barriers around their star to harvest energy. How cool is that? And why haven’t we heard from them? My suspicion is that the speed of light is indeed a barrier (no free FTL lunch), and interstellar space is very, very large.