You drift apart.
You leave and after meeting some of the critters out there you realise that your humanity is not as valuable as you were taught to believe.
Your intelligence is really just an ability to play status games with big apes of African savanna. Why would any machine even try to pass Turing test?
Don't ask me! I am busy preparing for honey-gathering contest with bees.
You visit Uegzihls of Beta Tauri and maritime Kranns of Alpha Aquarii. You meet Nee-gued with feet in opposite direction so that one who tracks it gets to the place where it came from not where it went. You face Übermenschen from Canis Major able to cook a beef stew using pure force of will.
You meet cunning Wlurfs and gentle, reclusive Mips of Al-Sharatayn.
You ask them how does it feel when your mind had evolved in predator/prey arms race rather than in in-group competition for mates as ours did. And you get no answer. Wlurfs can't speak. They can't communicate even among themselves. The best they can do is basic sexual display.
What a lonely and deadly existence!
If SETI sent them a message with Pythagorean triangles to signal that we exist and that we are capable of abstract thought what would they make of it?
Wlurfs would ignore the maths but they would get a pretty good idea of human weak points. Even a slightly dumb Wlurf would come up with at least a dozen of ways to hunt us down.
Mips, on the other hand, would make sure that the signal won't reach them ever again.
But even so, what about intelligent grasslands of Zarlia? And what about intelligent crystals from Cetus Junction? Spend few weeks among them and you'll wish to give Wlurf a tummy rub.
And don't get me even started about the notorious intelligent gas from St.Pauli!
In the end, the races may differ but after couple of eons in vacuum, where meeting a hydrogen atom is a notable event, an individual becomes as strange to the rest of their species as any alien you may encounter north of Aldebaran.
Hear what grandpa says: The real problem with the twin paradox is that once the space-faring twin returns home he'll find out that his brother has in the meantime morphed into semi-intelligent foam filling the oceans of their native planet. Or into megacorporation that seems to produce nothing but gravel. Or something. You cannot tell in advance.
My mother-in-law used to work for a hedge fund. After she retired she settled at her causal patch in Nebraska. Million or so years later she was found dead in the kitchen. Investigators said that her bank account had become sentient. They said it wasn't a pretty sight. Now go figure!
TO BE CONTINUED
Martin Sústrik, March 27th, 2016