Alien Cultures through the Galaxy
The famous "Drake Equation" attempts to tentatively give an answer but muddies the waters somewhat by failing to define "civilization" in reference to how many alien civilizations might presently be trying to communicate. We have an intuitive idea that civilization therein described means a civilization within a single solar system. But it could also mean any number of related solar systems which developed from a single home planet. If we acknowledge that colonization of the galaxy is possible (which project SETI cannot do) ... then ... another term must be added to the Drake equation ... fcol ... the fraction of planets where intelligent life does not arise but which are sending signals anyway. Then, of course, we have to get into the rate of colonization and then we find what no SETI investigator wants to hear. i.e. that there are communicating civilizations all over the place but apparently not in the electromagnetic spectrum ... or ... they've somehow masked their transmissions, i.e. they don't want to talk to us.
At the low end of the spectrum we have Enrico Fermi stating, "Where are they?", about the existence of extra-terrestrial beings. This a perfectly normal response to back-of-the-envelope type calculations which show that if there are any appreciable number of such civilizations ... then ... they should be here already. And also we have Tipler and Barrow's statement in "The Anthropic Cosmological Principle" that we may be the only intelligent species in the galaxy for the same reason as Fermi, i.e. if anyone were here, they would have seen them by now.
I will take what I believe to be a conservative view in regard to number of indigenous civilizations developing in the universe. I'll say that there are only 10,000 so far. Thus, I am taking the view that only one star in 20,000,000 develops an intelligent life form capable of communicating with us. But ... I will also take the heretical view that it is the norm that such a civilization will expand beyond its own solar system. This view is not acceptable in mainstream science because it results in calculations which become "uncomfortable". It is OK in the scientific mainstream to say that travel between stars is possible ... but ... one must now draw from this any inevitable consequences.
Another consideration is the lifetime of the civilization which is often morbidly placed at some short range. Thus, we are certain to cease trying to communicate with others outside the solar system within ... [pick your number of years]. Here, I believe the only responsible answer is to take our cue from the lives of individuals and state that only a small percentage will commit suicide and the rest will try to go on as long as possible. After all, if a civilization survives for 1,000,000 years, why would the inhabitants then decide to 'end it all'. Clearly, the lifetime of a civilization, barring a natural global catastrophe, is indefinite and ranges to the lifetime of the planet itself. In fact, the possibility of a global catastrophe would be another good incentive to migrate away from the home planet.
One last remark here. If the duration of a civilization is indefinite, over what span of time do the 10,000 original planets evolve? We must consider that the development of beings cannot occur until enough heavier elements have been formed to make planets, etc. So, I'll just guess that no intelligent life form evolved until about ... hmmmm ... let's say 4 billion years ago. So we have 10,000 civilizations developing starting about 10 billion years after the universe began (according to present theory).
Here are ten thousand planets with indigenous lifeforms
This is a rolloverimage. Each red pixel is one home planet. The thickness of the galaxy is ignored here so imagine them spaced out uniformly in that dimension.
That's quite a coverage. If we get liberal in our estimates, we couldn't render each as one pixel. There wouldn't be enough room at this resolution (468x397= only 186000 pixels for the whole image). The indication here is that given our being an average planet in the 10,000, we can expect there to be 5,000 which developed before us. What we need to know now is how the galaxy is colonized in general terms.
Let us consider that each home planet sends out two successful colonization expeditions to other solar systems ... and subsequently ... that new colony proceeds to send out two more expeditions after it has established itself in the new solar system (terraforming, populating, etc.). Then we have a rate which doubles every so many years. Let us further consider that there is another inhabitable solar system on average about ten light years away from any other (a reasonable estimate given what is known about our galaxy). Then,
which is about the total number of stars in the galaxy. Thus, after going only 380 light years, we'd have enough expeditions out to colonize the whole galaxy!? Obviously, the density of available stars does not support such a doubling rate ... unless ... each colony sends its expeditions on longer and longer journeys.
It is for this reason that the length of time needed for a new colony to develop enough to send out another expedition becomes irrelevant in the big picture. Whether it waits 1000 years to send out the next expedition or 10,000 or even 100,000, little difference in the final time of colonization is effected. Longer times for development only make the colonization procedure seem to start more slowly. In any case we need just 38 x (development years) + we simply add some amount of time to account for ...
The velocity of the expedition craft
To contemplate inter-stellar travel, a minimum velocity of 1/1000 of the speed of light is required. Stars in the galaxy have relative velocities on the order of a hundred miles per second so it will do no good to arrive at the destination solar system if that star goes whizzing by much faster than you can catch it. A more realistic velocity might be 1/100 or perhaps better 1/10 of light velocity. Much more than 1/10 gets into bigger problems than I think are worth solving, i.e. if you are willing to spend your lifetime traveling through space, what difference does "How long" make?
At 1/10 c, it will take a maximum of 10 x 100,000 light years (galactic diameter) = 1,000,000 years to cross the galaxy. Now add the above development time and we get ...
high speed colonization
(38 x 100,000) + 10,000,000 = 13,800,000 years
There are of course many other factors which might slow up or speed up colonization. Any colony or home planet might send out many more than just two expeditions. Why not one every 100 years after they are fully developed? It could be like dodge'em cars out there. Or maybe they get lazy and just kinda' peter out after going a few hundred light years. The point here is that if any civilization wished to colonize the galaxy ... and ... travel between stars is possible ... and ... there are many civilizations out there ... then ... the galaxy should already be totally explored and colonized ... and long ago ... just by the statistics of the situation.
We have (in this analysis) several thousand civilizations that developed in the last 4 billion years (before us) and it would take any one of them certainly less than 100,000,000 years to colonize the entire galaxy. So where are they? This is the question and line of reasoning not allowed at project SETI or in public discussion of the subject by "reputable scientists".
If the galaxy has not been already colonized ... then ... we must be in the statistically unusual position of being one of the first civilizations to develop ... or ... interstellar space travel is impossible (the SETI viewpoint) ... or ... there just isn't anyone out there at all ... or ... virtually all technological civilizations destroy themselves almost immediately upon gaining complete control over nature, i.e. the "Hollywood" position (it makes for conflict and therefore better stories).
On the Development of Interstellar Civilization
Any culture that reaches a point where travel to other planets is an option has necessarily gone through a "transition" from primitive animal behavior to advanced intellectual endeavors. Such transitions may take several thousands of years as evidenced by our own present experience. We are at the threshold of going to other planets and the case might be made that we are in the middle of our "transition".
Such transitions are marked by an extremely steep development curve preceded and followed by a much more gradual rate of learning. Some people imagine that there are an infinite number of basic principles to learn in existence. There are not. After the basics are learned (no matter how long that may seem to take) there is little else to do but fill in the gaps. Certainly, there will always be things to discover but not things of great significance. Hence, I have said before that the Earth as it will be 100,000 years from now will not be significantly different from the Earth as it will be one billion years from now. Whatever is possible will be known sooner rather than much later. There are only so many ways to arrange words to compose our thoughts concerning the causes of what we observe.
The End of Natural Selection
For any culture that has transitioned into a potential galactic colonizer, natural selection by primitive life and death struggle comes to an end. Such beings still undergo physical changes but they are by means of sexual selection, that is, conscious choices are made about which direction the species is to go in.
In the more advanced cultures of the Earth at present this is already occurring. In America we no longer worry about struggling with nature to survive. Rather, we pick our mates on the basis of looks and emotional-intellectual compatibility. You can see that the present trend is to the "caricature' of the human body. The differences between men and women are being accentuated to enhance sexual appeal which is leading into perhaps a dolphin-type existence where life is carefree and sexual relationships are of paramount importance. This will be an immature adult phase which may last for many centuries. It will gradually be replaced by a more sedate culture that is less concerned with emotion and more concerned with intellectual pursuits.
As I have pointed out elsewhere, there are only three basic motivations possible to sentient beings in existence.
Since we need no longer worry about number one (we hope), we begin to concentrate on number two. When we have got our fill there, we will be concerned with just being ourselves ... and because we are by nature curious we can expect that nature to be expressed by expanding outward into the galaxy to see what is there ... to collect data ... just to see because we wish to know. That is our final identity.
If the Galaxy has already been Fully Explored ...
Where are they?
The conjecture of greatest probability is that some UFOs seen here on Earth are from other planets. If this is not so and the entire phenomena is a psychological aberration, then one must accept that one of the presently believed to be improbable possibilities is true. Perhaps there really is no one out there.
If we are presently being visited some conjectures can be made about their behavior and appearance. I will consider only the most commonly sighted "beings" ... the so-called "grays".
Because they are small some have conjectured that they come from a planet with a lesser gravitational field. I believe this to be false. More likely, they have simply paired down their physical existence to supply them just with what is needed to get around. They have no need to wrestle physically with anything so that over millenia sexual selection would presumably produce smaller bodies. There is less maintenance as well. They have no hair because it is a dirt collector whose only practical present use (on Earth) is involved in the attraction of the opposite sex. Hence, if an advanced culture is no longer dwelling on sex (as we are), it would be a desirable thing to lose. Also, they have no kinds of disfigurments at all. It would be difficult to imagine an advanced alien wanting to get a tattoo of a spaceship on his chest.
They talk little seeming to communicate by telepathy. This is undoubtedly impossible. Rather, they probably know each other so well that each knows what to expect from the other and all can see what is to be done without verbal conference. The merest nod or look is sufficient to get the message across.
Their brains are large to accommodate more information. Their eyes are large to see in greater detail (perhaps into the infrared which would be desirable in darkness). Their eyes are solid black not because they don't have pupil or iris as we do but more likely have a covering analogous to "sunglasses" protecting their large eyes.I'm quite sure that if I had very large eyes, I would be uneasy in any environment where foreign objects could hit me (dust, mosquitoes, fingers, etc.). Perhaps they only take them off when they go to bed (if they go to bed).
The prevalent attitudes
Though the presence of extra-terrestrials is the most likely hypothesis, it is unacceptable to mainstream science because it cannot be observed on cue ... and ... even if it were verified nothing would change since they clearly have no intention of communicating directly with us. Hence, it is better to pursue other matters which can potentially lead to fruitful developments. Whether they are real or not, the best plan is to "go about one's business".
I regret that I personally have no "sighting" to report in my 55 years of living. On one occasion in the 80s, I was at the Hudson Valley Mall in Kingston NY when a woman in the parking lot pointed to a formation of lights in the distance. I looked at them and observed what appeared to be, about 2 miles distant, about a dozen lights in the formation of a chevron and must have been possibly as much as a half mile long (an impossibly huge craft). I replied to her that they were undoubtedly the formation of powered hang gliders trying to generate UFO sightings which I had read about in the papers. I examined the speed at which they were "wheeling" in an arc and decided that the inside light was traveling at greater than the stall speed of a hang glider and that the outside light was traveling within the maximum speed of such a glider. (I had seen these craft during the day on many occasions but not in formation.) I couldn't find any other marker in the sky to check for an occlusion so couldn't rule out its being a solid object. Nor could I hear a sound which I attributed to the distance and possible temperature differences which could curve the sound upward.
I regret that I did not stay to observe the "thing" for as long as possible as I am sure I would have scoped out something to show that they were separate objects. Instead I left to do other more interesting things ... still ... they kept such straight lines ... a perfect chevron wheeling in a broad arc without pilot error. Very masterfully done. It is easy to see why people could get duped ... but ... perhaps not all of them.
More than likely ...