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?
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.
https://www.forbes.com/sites/chadorzel/2016/05/04/the-real-r...
P.S. It's really funny to see forbes as a source of science.
I'm happy there are at least some universal constants like absolute zero or the max possible temp or planck length.
And as for anything FTL, I hear it breaks the rules of causality and that seems to be a big no-no and is indeed impossible.
The physics we have at any given time is tested through experimentation, and has proven effective and accurate to some degree. Within those parameters it's verified.
So skepticism of current physics makes sense to a point, we know it's not complete, but we also know that in a massive range of many complex and sophisticated tests it turns out to be precisely accurate. That's got to count for something.
Testability is a strength not a weakness, it means we know for sure what the limits of our understanding are. Outside the domain of science we have no such heuristic, so we have no idea whether or to what extent anything we think up bears any relation to reality whatsoever.
Do you have an alternative?
So far the only quantum communication we've done over distance is via photons, which are still photons.
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.
Genuinely curious - why does that worry you?
If the universe is neutral or friendly to civilizations, then we should expect to find someone out there in fairly short order. The universe is so large, even if there’s only a one in several billion chance of a particular solar system birthing a civilization, there should be a few others besides us already in the Milky Way.
If there’s not anyone else, the best case is that we are simply the first (this is my personal bet). Worse scenarios include civilizations simply fail and die after some time, or that one “predator” civilization kills off any other civilizations it finds before they can become a threat.
This would be odd given that 95% of the stars to ever be created in our universe have already been made. https://nautil.us/issue/104/harmony/the-universe-already-mad...
To think that with billions of stars, each with at least one planet, intelligent life only happened on one planet (the Earth) means intelligent life is super rare, even if life in general happens on many planets.
This means if we get hit by an asteroid or don't get passed the Great Filter, the only ones who "think" about this universe and give a meaning to it will be gone forever.
The rough idea is that the galaxy seeming insanely quiet could potentially imply that it's rare for life to reach a level which we can easily detect; space-faring, multi-planetary, capable of astro-engineering, etc.
If that is the case, it might be that there is a "Great Filter" which tends to knock these civilizations back into their stone age, or kill them outright. Maybe it's nuclear weapons, or grey goo, or biological experiments that break containment, or an AI that decides to kill its makers, or even just conventional wars that stunt their growth, etc. Generally, some kind of technological development or societal event that leads to that civilization going/staying dark to the galaxy.
The potentially worrying question is: have we passed the Great Filter? Or is it still somewhere in our future? There are any number of things that might kill or stunt humanity in its crib, before we spread out far enough to be able to persist.
And even then, how long is it going to be before a nuclear holocaust on Earth would no longer effectively cripple humanity, even if we've colonized the solar system and could nominally survive it? Or imagine AI-infused grey goo that spreads throughout the solar system.
There may also be more than one Great Filter.
1. it offers no testable predictions
2. it explains everything, yet explains nothing
I’d go further and say they require such a being, despite us having reason to believe such a being is not compatible with our understanding of how the universe actually works.
Just as the existence of an all powerful eternal being doesn’t seem compatible with what we know about what’s possible in the universe, I have severe doubts that a simulation of the fidelity we observe in our existence is practical to build in our universe.
It certainly isn't. You can't simulate three atoms using two atoms. There's no reason another universe has to abide by the same rules as ours, though. It's not something anybody should actually worry about but it's about as scientific an idea as string theory is.
That's not necessarily a ringing endorsement ;)
At least string theory has lead to some very powerful and productive mathematical techniques, if little in the way of actual physics.
If we can invoke other universes, then we're kissing Occam's razor goodbye and we're in magical fairy land territory.
As a biologist I'd love it if they found life (that was totally seperate from Earth life) somewhere else in the solar system, but if we do it's one less great filter.
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.