I hope there's intelligent life somewhere in the universe as there's bugger all on earth..
It might get to our nearest star, Proxima Centauri, in a little over 4 years, and then another 4 years to receive a reply assuming there's a planet hosting intelligent life in the system, but I suspect 20,000 light years away may take a little longer, I'd guess about 20,000 + 20,000 years or so.. Trappist1 would be 39 +39 years give or take a second or three according to the published data...
"It would mean, that extraterrestrials over at Trappist-1, for example, would be constantly bombarded by the light." - No - a quick flash once a day, perhaps as the earth rotates and they'd only notice it if they had infra-red sensitive eyes of incredible sensitivity..
Is that the standard of MIT graduates/professors these days? We're doomed, (hence the icon)... I know this is to be taken with a pinch of salt but the old saying "people may think you are stupid, but why open your mouth and remove all doubt?" seems to apply here.. This has got to be clickbait, surely? It's the sort of bogus science that is seen every day in the media with their arts graduate 'science' correspondents..
Is it me or is the biological infestation on our little piece of rock getting dumber? Personally I blame leaded petrol/gas..