https://en.wikipedia.org/wiki/Arecibo_message
was repeated I’m sure most civilizations could figure out that it was a raster but if it is sent once the odds are awful. Past that what would they understand? If we sent it today we wouldn’t put Pluto on the planet list. Maybe 10k years from now there are a trillion people living on Ceres and it would be unthinkable to waste volatiles to fly to some dry spot like Earth and we’d again send a different message.
Figuring out the raster structure of NTSC television seems straightforward and even if they never figure out how color was encoded I think they’d still get a lot out of it even if their senses were different and they couldn’t “watch” TV. I am skeptical though that anybody would figure out how to decode the current ATSC signals, never mind the new ATSC 3 standard or 4G or 5G wireless signals that people stream TV over.
In order to know what they might do, let alone how, we would first have to know why. And their why is not going to be our why. Anybody's why is determined by what they are right up against. (This is why evolution immiserates, because it guarantees that we spend most of our time at the boundary of our envelope.)
I am sure that aliens who can build computers know about the halting problem but they probably formulate it differently. [1] I doubt they have 8-bit bytes. They probably, like us, skipped Indium Phosphide, Gallium Arsenide and such for Silicon, but I'm not so sure about that.
[1] Turing started out with a line of though that seems oddly disreputable now: we know most of Cantor's phony numbers (that we call the "reals") don't have names [2], but some of them, like π do. Is the difference between the named and nameless ones that we can program a Turing machine to print out the named ones?
[2] ... hence less "real" than the integers
(The one thing that they will have, even if to their distaste, is powers of 2.)
ETA: If Turing was trying to make a distinction between the finiteness of the symbol for (say) the square root of three, versus the infinitude of the process that must be executed to evaluate it, that would be not so much disreputable as nonsensical. He was fond of setting up straw men; let us suppose that this was one of them.
Or the alien life may consider us to be akin to scum on a pond and not worth communicating with.
PaulHoule•9mo ago
A ‘type ii’ civilization which could disassemble terrestrial planets could point a big-ass laser at us which we could see but maybe they don’t all (or ever) get that big. And they have to be motivated to do it.
If you want to visit another star you have to stop at the destination which is almost as hard as getting to speed but if you want to communicate a message which cannot be misunderstood you could bomb a planet with relativistic speed projectiles. Now maybe the average type ii civilization would not do that but maybe the fear that another one could so that might motivate a preemptive attack. It adds up to it being risky to attempt contact so why try?
Consider this message
https://en.wikipedia.org/wiki/Arecibo_message
to a star cluster 25,000 light years away. Even if somebody in that 300,000 star cluster has a telescope pointed in the right direction and the right time we could be long gone by the time they get a message back to us or maybe we forgot we sent it or now most of us live on another star…
rbanffy•9mo ago