When SETI tries to look for aliens, they always try to catch the echos of radio waves sent out from alien civilizations. But would an advanced civilization even bother to use radio waves? Are there hypothetical communication systems that are superior to radio waves? Or are radio waves truly the best way to go?
Kudos to Justin for mentioning entanglement. His idea about using quantum physics and more advanced, hitherto unseen technologies is right on spot.
I'll just add another option that I think is in the same spirit: tachyons. They are theoretical particles with a rather interesting set of properties:
- They travel faster than light. They can never slow down to light speed;
- Moreover, the less energy they have, the faster they go. When their kinectic energy approaches zero, their speed tends to infinity;
- Due to their FTL nature, they may also allow communication backwards in time.
Infinite speed makes for faster communication than sending regular particles through wormholes. Sending messages to the past makes it even faster than entanglement, though in sort of a cheating way.
If they were really advanced, the answer would probably be 'no they would not bother with electromagnetic communication'. Any electromagnetic communication would be spurious noise, some form of an anachronism. It really is, for interplanetary communications, quite limited and inefficient. In perhaps another century, humans could very well be remarking at our dependency on it, the same way we remark on our former dependency on the 'pony express' and snail mail.
It is to be expected that their physics text book is much, much thicker than ours.
With the advances that are being made in quantum physics, there is every indication they would use such principles as entanglement (principles that we are only guessing at), for instance. The notion that some will posit - that such communication is impossible - only slows down our discovery of it.
Edit See for instance Scientists Achieve Direct Counterfactual Quantum Communication For The First Time
Edit And another article Nil Communication: How to Send a Message without Sending Anything at All
I have absolutely no doubt that there are quantum fields that we can not even speculate on. We just discovered the Higgs field, for instance, a previously unimagined and unimaginable field previously. There is no justifiable reason to believe that it will be the last one discovered.
Even the Higgs field itself, if it could somehow be manipulated, could lead to some new form of communication.
As Einstein himself called it. 'spooky action at a distance'. Just because Einstein had no use for it, and could not comprehend such a thing, does not make it impossible.
An advanced alien civilisation would likely have a more advanced means of communication than radio waves. In order to become an advanced civilisation however, they've likely passed through a period where (like us) they've relied on radio waves for their own communication.
We as a species engage in archaeology to understand the past; we can hope that they might look at the radio spectrum as we do, looking for younger races. This of course assumes that their technical development has occurred in parallel to ours. It's possible that they've not discovered radio waves during their development, in which case they wouldn't think to look for them any more than we look for signals in gravitational waves, for example.