In 1938 Orson Welles put on a radio show in New York City that dramatized the famous novel by H.G. Wells, _The War of the Worlds_. This novel is about an invasion of Planet Earth by intelligent beings from Planet Mars, with this invasion just barely being defeated. Several movies have been made of this famous novel, probably the first to present this now long-running sc-fi theme of our planet being invaded by aliens from outer space. However, whar was especially important about this particular radio performance 80 years ago is that many people turning on their radios and hearing ongoing reports of a Martian invasion of New Jersey is that many people believed it and a temporary panic ensued. Lots of people thought it highly likely that Mars was inhabited by intelligent beings who were a threat to us.
How things change. Now we have sent several vehicles to Mars, where not only are there not dangerously threatening intelligent beings, but we have yet to find any signs of even single-cell life, although the recent discovery of some actual water there may yet possess the possibility that some simple form of life is there, or perhaps was, although increasingly the search for probably only single-cell life to moons of Jupiter and Saturn, with no luck so far. If there are intelligent space aliens, they are on planets in other star systems. However, until recently, given over 100 billion stars in our Milky Way galaxy, various estimates of the probabilities involved had it as near certain there is life elsewhere in the galaxy, and also highly likely that there is intelligent life of some source, probably on multiple planets. And we have indeed discovered “exo-planets” around many stars (I note that my brother-in-law, Michael Werner, has long been a major leader of the search for these exo-planets using the Spitzer infrared telescope).
These calculations suggesting a high probability of intelligent life elsewhere triggered the initiation of the Search for Extra-Terrestial Intelligence (SETI) about a half century ago, sending out various messages hoping to get a reply from somebody out there. So far there have been no replies. This has begun to shift views to the point that now we have flipped to the opposite view of that held in 1938: now we have commentators suggesting that the probability of life is much lower than previously thought, that we arose from a very curious and special set of circumstances, these so weird we may in fact be alone in the galaxy, and even possibly in the entire observable universe.
A recent example is an article in the latest Scientific American (September, 2018): “Alone in the Milky Way” by John Gribbin (subtitle, “Why We Are Probably the Only Intelligent Life in the Galaxy”). He notes a sequence of supposedly “improbable coincidences” necessary for even simple life to arise, much less technologically advanced intelligent life like we are. Supposedly we are lucky that earth was formed late in the life of the galaxy, allowing us to accumulate lots of metals. Also, supposedly only a narrow band of the galaxy will support life: too close to the center too many “accidents” and too far not enough metals for building rocky planets. Then there is the matter of having a rocky planet just the right distance from a star in a Goldilocks position: not too hot and not too far. Gribbin notes that it only took a billion years from earth’s beginning to get single-cell lift, but much longer periods to get to more complicated forms, with the jump to multiple-cell organisms onl coming 700 million years ago. Then there is the matter of actually evolving beings as smart as us, with Gribbin noting that our ancestors nearly went extinct about 70,000 years ago. He says this string of events is so improbable that probably we are “alone in the Milky Way.” Many are now taking such arguments seriously, with Tyler Cowen at Marginal Revolution just a few days ago posting an estimatte of “the economic value of the [observable] universe” (about 60 septillion dollars, supposedly), with this estimate being based on the assumption of one planet per galaxy like ours with beings like us and economies like ours.
All this may be correct, but I have a suspicion that this is one of those swings that is going too far in the opposite direction of what was previously widely believed,in short, an intellectual fad. For starters, SETI has only been at it for about half a century. If some intelligent beings have heard us and responded, their message will need to get back to us, which means that the effective distance of SETI is only about 25 light years. The Milky Way is 100,000 light years across, so SETI has effectively reached only a tiny portion of our galaxy, tiny to the point of miniscule. I could poke at some other of the pieces of the argument, but will not go beyond this point here. My guess is that the probability of intelligent life in our galaxy is higher than Gribben estimates, although maybe not as high as thought several decades ago.
This said, I came to the bssic conclusion that we may be rarer than previously thought some years ago, indeed due to thinking about the non-response to our SETI transmissions. This led me to come to a similar ultimate conclusion as Gribbin does in his article: that if we are so alone and special, then this puts on us as a species a special responsibility to manage our planet and ourselves especially carefully. I definitely think this. Indeed, I came to this point at the very end of my 2011 book, Complex Evolutionary Dynamics in Urban-Regional and Ecologic-Economic Systems: From Catastrophe to Chaos and Beyond, at the end of a chapter contemplating the problem of climate change. I closed the main text of the book by quoting Nasssim Taleb from his book, The Black Swan:
“Imagine a speck of dust next to a planet a billion times the size of the earth. The speck of dust represents the odds in favor of your being born, the huge planet would be the odds against it. So stop sweating the small stuff. Son’t be like the ingrate who got a castle as a present and worried about the mildew in the bathroom. Stop looking the gift horse in the mouth – remember that you are a black swan.”
To this I attached a footnote, the actual last thing in the book (except for a mathematical appendix), which says (p. 211),
“A broader perspective of this involving planets is the absence so far of any signals indicating life on other planets by [SETI] that has going on for decades now…The apparent rarity of life such as ours, at least in our region of the galaxy, suggests that we may face a greater responsibility than we thought for the proper care and stewardship of our planet and its global ecosystem and noosphere.”
Gribbin concluses (p. 99) that, “And if our planet is so special, it becomes all the more important to preserve this unique world for ourselves, our descendants, and the many creatures that call Earth home.”
Barkley Rosser
“…that if we are so alone and special, then this puts on us as a species a special responsibility to manage our planet and ourselves especially carefully.”
I might take the opposite view, suggesting that such a statistic indicates that we are an accident that should never have happened and that the sooner we let our planet return to its natural condition the better, so that the universe is no longer flawed by this one accidental anomaly.
In our fossil record there is a mass wipe out of species every 26 million years. One of these freed our furry mammal ancestors from hiding in the night from the dinosaurs. As such it seems like the process of evolution on earth has been radically speeded up.
The fossil record only goes back 260 million years because there were no species that could preserve before that. Presumably the same thing that subjected earth to repeat comet showers may have been hitting it from the beginning.
Perhaps if evolution on our planet depended mostly or only by random drift mutation it would have taken much longer than the ten billion year life of our sun for intelligence to evolve.
* * * * * *
If intelligence evolved without sufficient metals to support industrial development and science the humanoid races must live forever in hunter/gather mode. Probably — by normal distribution — a significant portion of humanoid populated planets exist in permanently primitive conditions.
If we discover such, what kind of help could we send — assuming this discovery happens a century or more from now when we could send robotic assistance? We would have to study them first. Perhaps we could send out AI robotic scouts to do the whole thing for us — give the limits of interaction imposed by the speed of light.
* * * * *
Did God do a sneaky by including silver and gold in His table of elements — purposed to speed up economic development? We take the two so for granted.
The fact that they aren’t already here is evidence technological civilization has been rare, but perhaps not that it will be.
Bill H.
Well, I do think that human civilization has produced some good things, so I do not particularly see anything desirable about us going extinct or there not being any other intelligent life anywhere else. Of course we have other species who are quite intelligent, see dolphins and elephants and bonobo chimpanzees and quite a few others. It is just that they have not developed high technology.
DD,
I have not previously heard of any regular 26 million year cycle of major extinctions. I do not think there is such a thing.
Lord,
An alternative and very likely explanation is that the speed of light really is a limit, no sci-fi jumping into hyperspace. In that case, well, it takes a really long time to get from one star to another, so why would some alien species spend the huge time and effort to get to our solar system, especially given that we only atarted sending out SETI messages a half century ago?
The fact that they aren’t already here is evidence other life forms have observed our behavior and have quarantined our planet.
BR
Mmm; maybe, maybe not.
https://upload.wikimedia.org/wikipedia/commons/thumb/6/6b/Phanerozoic_biodiversity_blank_01.png/450px-Phanerozoic_biodiversity_blank_01.png
“Nemesis is a hypothetical red dwarf[1] or brown dwarf,[2] originally postulated in 1984 to be orbiting the Sun at a distance of about 95,000 AU (1.5 light-years),[2] somewhat beyond the Oort cloud, to explain a perceived cycle of mass extinctions in the geological record, which seem to occur more often at intervals of 26 million years.”
https://en.wikipedia.org/wiki/Nemesis_(hypothetical_star)
More fun: imagine that some earlier arrived (than us) hitech civilization out there somewhere, long ago sent out an AI robot fleet to help develop any humanoid species trapped on a planet without sufficient metals to develop technology and science to develop technology on their own (trapping them in tech ignorant hunter/gathering). Imagine that that fleet showed up on earth.
What would it do? What would we do. I would guess that since the fleet probably received continuous updates that it could probably move us shall we say “light years” ahead of where we are — if it wanted to.
DD,
I just wasted my time checking on this stuff. There is a paper in 2015 making the 26 million year cycle tied to supposed comet cratering. I then saw other papers tearing this to shreds. I do not know how that incompetent wacko paper got published. There is more evidence for 140 million ,62 million, and 31 million year cycles than 26, but even for those the evidence is weak. Eyeballing the actual pattern of extinctions shows no cycle whatsoever to me. Looks like a bunch of random exogenous events, especially for the “Big Five” extinctions over the last 450 million years, the last of which was the one that wiped out the dinosaurs 65 million years ago.
As for Nemesis, note it is strictly hypothetical. It was hypothesized back in the 1980s by a guy named Muller. Since then there has been a serious search for it. Nobody found it and everybody has pretty muc given up on it, with even Muller retracting his theory. This is a dead theory. The alternative for a cause for a periodic mass extinction from comets is crossing the galactic plane, which our solar system is beginning to do for the next couple of million years or so. However, there is no evidence tying this to any of the observed major extinction events.
The rest of what you post is basically sci fi, fun as it might be to think about such stuff. Look it may be disappointing if indeed the speed of light really is a hard limit, pretty much ruling out any serious interstellar travel, but this is no worse than losing the belief people had 80 years ago that not only was there life on Mars, but it was seriously intelligent life. We may just be stuck by ourselves effectively, even if there is a lot more highly intelligent life out there than Gribbin thinks.
Colonizing the galaxy might take a million years, even without FTL, that is whether there is life there or not, and earth would have had an oxygen atmosphere for over a billion years. Colonization may not be that attractive, but would it be that unattractive? Will we sit here the next million years waiting for signs of someone elsewhere?