File this one under how is this news, or maybe arbitrary number that makes headlines because someone said so, but still:

Under the strictest set of assumptions – where, as on Earth, life forms between 4.5bn and 5.5bn years after star formation – there are likely between four and 211 civilisations in the Milky Way today capable of communicating with others, with 36 the most likely figure. But Conselice noted that this figure is conservative, not least as it is based on how long our own civilisation has been sending out signals into space – a period of just 100 years so far.

Want to chat with said alien civilizations? Then we’d look at 6,120 years for a reply… Yeah, technology’s not really there yet.