Over the past two decades, a combination of techniques and studies have so far found 925 planets in 713 systems (presumably excluding ours) in a bubble centered on Earth roughly 300 light years in diameter. Considering the Milky Way is 250,000 light years across, that's a tiny fraction of one galaxy out of 170 billion. I won't post any links. You can verify the numbers easily enough.
There are a lot of estimates out there, but the median guess is that there are a couple of billion Earth-like planets in the Milky Way alone, meaning roughly the same size, water/oxygen environment, Goldielocks Zone, etc. Just 20 years ago, we could put any number here, but using statistical reasoning (take it for what you will), we now have a fairly reasonable assurance of some kind of validity.
A number of years ago, a fellow by the name of Drake came up with a back-of-the-envelope equation as a talking point for a symposium. The idea was to somehow quantify the idea of possible life in the Universe. Some of the variables were fairly well agreed upon, others were just plucked from the air, but no matter how you sliced it, you got a pretty big number for an answer.
This led to the Fermi Paradox. You have probably heard of Enrico Fermi in high school physics, but you may not know his paradox:
- The Sun is a young star. There are billions of stars in the galaxy that are billions of years older;
- Some of these stars likely have Earth-like planets[2] which, if the Earth is typical, may develop intelligent life;
- Presumably some of these civilizations will develop interstellar travel, a technology Earth is investigating even now;
- At any practical pace of interstellar travel, the galaxy can be completely colonized in a few tens of millions of years.
In other words, why aren't we up to our Blessed Assurances in extra-terrestrials? Another question that arises is how likely is it that Earth is a colony of some other civilization?
Aye, there's the rub.
Without empirical data, i.e. some 'authority' offering us plebes indisputable 'proof' that we are not alone, then we cannot reasonably say without a doubt that we are not alone. However, given the statistical estimates based on observation that fall out of the data we have, it is unreasonable to assume that we are alone. We have found life in virtually every possible habitat on Earth, so why wouldn't life take to pretty much every habitat we observe in the Universe?
There is a growing minority that believes some combination of the following:
- the Universe is teeming with life;
- we are a legacy of some other civilization;
- we are being visited by other civilizations;
- we are actively engaged in contact with other civilizations.
The first premise I find hard to resist. Everything we have observed about life on Earth argues that the Universe produces life as a normal function of its existence. Given the umpteen trillion possibilities that we can reasonably assume to exist, we cannot possibly be the only result achieved. Whether all results have the ability to recognize each other, much less contact each other, remains to be seen. After all, we are still debating whether we are the only sentient beings on Earth. India just recently declared dolphins non-human persons and chimpanzees can learn and manipulate human language. We can't even agree on what constitutes intelligence.
The second point is a bit more contentious. There is a growing body of evidence that human civilization is a legacy of some past advanced society. Even if we dismiss myths such as Atlantis, there are still profound questions about the genesis of monolithic structures that predate anything approaching recorded history. There are hundreds of submerged structures, roads and cities all over the planet that exhibit advanced architecture and are obviously part of some earlier time when the Earth's coastlines were radically different.
There is also the mystery of our DNA. A large chunk of our genome is referred to as 'junk DNA', but a significant number of researchers question that designation. Others speculate that it serves some as yet unknown purpose. Still others say that it encodes data from a more ancient civilization waiting for us to discover how to read it. Much of this involves belief, which still requires a leap of faith. In other words, there is no surety, at least on the level of 'generally accepted' reality.
The third proposition is that we are being visited by other civilizations. Here we step firmly into the UFO argument. I think it is unreasonable to deny that there is a phenomenon called UFOs. I personally have had three experiences with aerial events that I still cannot explain with 'normal' means. There are also a great many respected and intelligent people who have witnessed these things, from astronauts to beat cops, and are presumably sober and professional in their descriptions.
Furthermore, the observed behavior of many UFO sightings show some kind of intelligent control, since they seem to do things and go places that exhibit premeditation and reaction to environmental conditions. Whether they are man-made, powered by ETs, or just dolphin technology remains to be seen. Too many of the reported sightings of beings inside the objects smack of religious delusions for my tastes.
I must conclude that they exist and that many of the phenomena exhibit intelligent control, but I reserve judgement on who or what that intelligence might be.
The final proposition is the most controversial: that some groups on Earth are not only in contact with, but are actively involved with extra-terrestrial societies. It would seem that the former Canadian Defense Minister believes this to be true. One assumes that he is a sober and reasonable man based on his title, but I also apply the "Weiner Filter" to any and all public officials.
From von Danekin to Linda Mouton Howe to Richard Hoagland, lots of people speculate on this particular idea, and (in the case of Hoagland) present a lot of evidence worth pursuing, to boot. Yes, the evidence warrants further investigation, but it is a bit premature to dive head-first into the "contact" camp without some evidence that meets 'reasonable doubt' tests.
What we can reasonably conclude is that there is a large and growing body of evidence that the Universe is full of life and likely other civilizations. We can also see plenty of evidence throughout the solar system that appears to be manufactured architecture, even massive spacecraft, that deserve much greater investigation, and not just swept off the table as 'tricks of light and shadow'. Far too much of it cannot be explained by generally accepted phenomena and methods.
There is a huge body of research on ancient myths and legends across hundreds of human societies that show remarkable similarities despite the common belief that far-flung humans had no contact in ancient times. Wallace Thornhill, Joseph Campbell and Joseph Farrell have, among many others, presented compelling arguments linking ancient myths to real phenomena.
What it comes down to is that we must approach these ideas with open minds. That doesn't mean unqualified acceptance, as is expected with religious beliefs, but sober and thoughtful consideration of the facts, and support of those efforts that seek to prove or disprove the conclusions.
Among those who believe that ancient human societies had no contact with each other, they posit that the distances and natural barriers between societies was greater than the technology of the time could overcome. Thus, they were unable to exchange ideas across great distances, such as the Pacific Ocean.
In the same way, those who argue that Earth cannot be in contact with other civilizations because of the vast distances and natural barriers that exist between star systems. Cosmological Pacific Oceans, if you will.
Yet, there are petroglyphs in California that bear ancient Chinese symbols. There are ancient Chinese records that show drawings of prickly pear cacti. There are Egyptian mummies that test positive for cocaine, and pyramids in Central and South America. There are symbols, such as the swastika, that span ages and continents. Obviously, there is an error somewhere in our currently 'accepted' history. It is thus reasonable to assume that if there are other civilizations, that we could have had contact at any point in our history, and the knowledge has been lost, hidden or suppressed for whatever reasons, and certainly undiscovered.
And that is the point. Clear thinking means that we may come to conclusions based on the evidence at hand. In fact, we must make conclusions in order to function with any amount of effectiveness. However, we must be open to new evidence, even if it contradicts what we have already concluded, no matter how seemingly fantastic it is compared to what we previously believed. All knowledge is open to new evidence, otherwise there is no use to calling ourselves 'thinking' beings.
Nor can we even call ourselves alive.
As J.B.S. Haldane famously said, "Now my own suspicion is that the Universe is not only queerer than we suppose, it is queerer than we can suppose."