It’s listed on Wikipedia without a date, but it’s first in the queue of Alastair’s uncollected short fiction, and it is The Big Hello, afterall, so you may as well read it first if you’re reading all of Alastair’s books: me thinks.
You’ll have to hunt around the internet for this, it was originally published in German translation in a convention program. But, like most rare things, it’s well worth a bit of a hunt around.
Basically, it’s a greeting from the rest of the galaxy informing us stupid Homo sapiens of a bit of etiquette, manners and how to go about things outside of out little insular bubble. But, let’s be honest, we all know people like Musk & Co. are going to ignore everything Alastair says and totally fuck it up for the rest of us.
