But if a civilization were circling a dying sun, for instance, that might be the way they would choose to have a chance at immortality.

My very favorite episode of ST:NG is a variation on this theme, except it involves direct memory transfer, from a probe left orbiting the swollen star into the mind of Picard, who lives an entire life as one of the extinct.

One might consider that every one of us who writes, composes, or creates art of any kind is launching a 'time probe': a palpable physical object that transcends the creator's lifetime. "Inscribed matter," indeed.

I recall a moment of wonder I once had, in a museum which had placed a carved stone pillar from its Egyptian collection deliberately within reach of the visitors, without protective barriers. You could touch the small bird some anonymous craftsman had carved more than 2000 years before and wonder if, while carving it, he thought about who might see and touch it, centuries hence.

It's a leap of faith, whether by an individual or a civilization, to send an artefact forward. You can never know if it will be found, and if you'll be remembered.