Maybe in the interval from when a species achieves sentience to some level where they leave this plain of existence altogether is not so great that they endeavor to spread throughout a large material area but rather before this massive undertaking is accomplished they have ascended. So, that is to say, one possibility to consider is that other intelligent beings may have already come and gone many times over without any perceptible (to us) trace of their existence.
Billy Brown wrote:
> Judging from the posts I've been seeing on certain threads recently, it
> looks like it is time to revisit this topic. Old-timers who've had the
> debate a dozen times already may want to skip this thread.
> The question at hand is this: "Given what we know about human history,
> human technology, and the nature of reality, how do we decide whether some
> novel idea about possible alien civilizations is plausible?" Or, to put it
> another way, "What is and is not predictable about alien civilizations?"
We have only our own against which to judge.
> There are several big mental pitfalls that you have to avoid when
> approaching this subject. Most people manage to get stuck in at least one
> of them, and consequently never say anything that is even remotely
> plausible. They are, in no particular order:
> Unrealistic Technology Expectations
> This idea comes in two closely related forms: "Future technology will be
> just like current technology" and "Future technology will be just like old
> science fiction." Wrong. This kind of thinking leads you to ignore even
> old, modest technologies like robotics and genetic engineering. If you
> want a realistic picture, you need to deal with the prospects for
> nanotechnology, AI, and superintelligence in a realistic manner. If you
> are going to dismiss them, you need to explicity say so (and supplying a
> justification for doing so would also be a good idea).
> Short Time Horizons
> We aren't talking about a few hundred years of event here. Or even a few
> thousand, or a few tens of thousands. Unless you think there is some
> special reason why technological civilizations have just now become
> possible, you need to deal with time spans of at least tens of millions of
> years. This is one of the reasons why most of us don't find scenarios that
> include technological roadblocks or galactic Prime Directive treaties to be
> very plausible.
> Insufficent Appreciation of the Effects of Diversity
> AKA "maybe not everyone will want to invent nanotechnology". It doesn't
> matter if 99.9999999% of all sentients spend all of eternity contemplating
> their navels. If I had the technology of 100,000 years hence, you can be
> sure my personal projects would be visible from distant galaxies. Simple
> evolutionary processes will give you a universe dominated by active
> explorers, even if almost everyone starts out being a homebody. This means
> that if you want to hypothesize a universe full of advanced civilizations
> you need to think really, really hard about explaining why they haven't set
> up shop here.
> Exaggerated Respect for the Immensity of Space
> The galaxy is big, but it isn't infinite. A single expansionist species
> with sublight travel could easily colonize every single system in it in
> less <10^6 years. Suggesting that we are surrounded by aliens, but they
> don't happen to have visited us, is equivalent to sugggesting that a
> particular lot on Manhatten Island might remain vacant for the next million
> Exaggerated Sense of Mortality
> AKA "maybe the aliens did thus-and-such, then died off..." What exactly do
> you think could have killed them? Most of the ideas I've heard wouldn't
> kill of modern-day humanity, let alone spacefaring aliens. Remember, even
> without nanotechnology, a single surviving colony could repopulate an
> entire species in a very short amount of time (instantly, form a geological
> perspective). If you use a realistic technology projection, and keep in
> mind that some small fraction of any population is going to be prepared for
> even fairly extreme emergencies, it is hard to imagine any event that could
> kill of a spacefaring species. Certainly, any disaster that big isn't
> likely to leave any intact planets in the galaxy.
> Billy Brown, MCSE+I
If there are an infinite number of alternate realities, maybe the truly advanced aliens have left us in this one to either observe or ignore us.
I think it is correct to consider what would be termed an actual "paradigm shift" in the nature of intelligence and civilization considering what might be termed as ultra-tech, as they say, to any sufficiently lower tech society magic.
Considering those aliens that might have ascended, that might be so, or those that attempt to do so are erased by those that already have. This is not such a pleasant alternative.
We might consider a wide variety of perceptual changes as technology becomes ultimately capable.
Whatever may be the case, until such time as the aliens are well verified and more or less come forward for themselves or not, those that would like the idea of alternate intelligences can feel good that there are millions upon millions of galaxies, each with millions upon millions of stars, each possibly with habitable planets per the Drake equation, that might foment intelligent life as we know it.
Interesting thoughts to consider, thank you for these. Have a nice day,
Ross A. Finlayson