A question I always had is wouldn't all sufficiently advanced civs use quantum communication which we wouldn't be able to detect with our usual SETI-style methods?
Quantum or not, any type of propagating and interacting particle or force can be used for communication. We primarily rely on electromagnetism but neutrinos, gravitational waves, charged or neutral particle beams etc. could be used as well. All of them have unique states that can be used to encode information. Spin, charge, neutrino flavor phases, etc.
As for entangled pairs, which I presume you imply by quantum communication, it really isn’t a hidden dimension with magical properties of superluminal communication, it just implies that two particles can have shared/correlated quantum states (assuming you can keep coherence). The coherence requirement basically means that the longer a particle is exposed to the normal world, the bigger the chances of some kind of stray interaction with other particles or forces, that will break entanglement. Further, for using this for anything, we’ll need to store the local particle for the duration of flight of the emitted one. That is also a technical problem of some magnitude if the distances are light years.
The short answer is that we don’t even come near to monitoring all “propagators” let alone all possible encoding schemes for these, for SETI.
Probably, but before getting to that stage, they most likely used similar EM waves to transmit signals. We must be able to detect at least some of that radiation, but still nothing. The galaxy is insanely quiet, which worries me.
On the other hand, it could be that they advanced to the age of using EM waves not too long ago, which means their signals are still on the way and we'll probably detect those in the future.
It's less that the galaxy is quite that's disturbing, as like you said it's possible EM based communication is only used for a relatively short amount t of time.
The fact that the universe seems to be totally natural, without any intelligent interference is more concerning. No megastructures or evidence that our solar system has been visited.
lokimedes|4 years ago
As for entangled pairs, which I presume you imply by quantum communication, it really isn’t a hidden dimension with magical properties of superluminal communication, it just implies that two particles can have shared/correlated quantum states (assuming you can keep coherence). The coherence requirement basically means that the longer a particle is exposed to the normal world, the bigger the chances of some kind of stray interaction with other particles or forces, that will break entanglement. Further, for using this for anything, we’ll need to store the local particle for the duration of flight of the emitted one. That is also a technical problem of some magnitude if the distances are light years.
The short answer is that we don’t even come near to monitoring all “propagators” let alone all possible encoding schemes for these, for SETI.
jasonlaramburu|4 years ago
https://www.forbes.com/sites/chadorzel/2016/05/04/the-real-r...
hulitu|4 years ago
P.S. It's really funny to see forbes as a source of science.
wumpus|4 years ago
So far the only quantum communication we've done over distance is via photons, which are still photons.
behnamoh|4 years ago
On the other hand, it could be that they advanced to the age of using EM waves not too long ago, which means their signals are still on the way and we'll probably detect those in the future.
ofTheFountain|4 years ago
The fact that the universe seems to be totally natural, without any intelligent interference is more concerning. No megastructures or evidence that our solar system has been visited.
jjulius|4 years ago
Genuinely curious - why does that worry you?