Shout in a Crowd,
How to Survey Galactic Civilization
Dreamed 2014/4/15 by Chris Wayan
for Nick Cowan of Amherst
Only now, after decades of dreamwork, do I discover what I've been up to on the nights when I have dreamnesia.
I dream that I've been testing how many inhabited worlds there are in the galaxy by trying the same trick on every planet I visit in shamanic dreams. I'm always wearing a local body of course, so I can mingle. What I do is find a crowd--a fair, an audience waiting to hear music or a play--even a political rally or protest. Then I shout "Hello! Do you speak English?" and then "Ni hao! Ni shuo zhongguo hua ma?" For nearly all Terrans have spoken either English or Chinese in a recent lifetime, if not this one. The populations speaking those two tongues are just so big.
Typical reaction: the vast majority hear someone babbling nonsense, but about 1 in 1000 has a visible shock of recognition, often unconscious, but strong.
I've conducted about a thousand such tests over the decades. The number of people reacting to Earth tongues suggests that reincarnation is common, but not restricted to Earth! Since Terra's population is massive compared to most inhabited worlds (the majority are low tech and thus low-pop; our population boom is unsustainable, so in deep time it'll be rare/short)... such a low percentage of reactors implies at least a quarter million currently inhabited worlds capable of massing a crowd; at least several million, total.
That assumes an even distribution of souls among them, which of course is unlikely. People may usually reincarnate locally; and even adventurous souls will likely go where there's a reasonable fit, not try to be people with, say, no humor or hair-trigger tempers (like, say, Terrans?)--unless they really need to. Or already are humorless, sigh!
But smart critters mostly evolve a recognizable spectrum of emotions; they're too useful. So most critters are compatible, and diffusion is broad.
Conclusion: number uncertain, but not a billion civilizations, nor a hundred. Mind you, that's current civilizations. Way more worlds are habitable, even inhabited, but cityless.
NOTES NEXT MORNING
A quarter million Milky Way civilizations, huh? And that's civilizations. Large, smart critters have lived on Earth 10,000 times longer than cities, fairs, temples, theaters. So my dream implies several BILLION (109) planets with advanced life in this galaxy alone.
EIGHT MONTHS LATER
Just heard a lecture at the California Academy of Science in San Francisco, by Nick Cowan of Amherst, on the narrowing estimates for life-bearing exoplanets. Now that we're actually seeing planets, it looks like this galaxy has 10-50 billion Earths or super-Earths; 10-50% of red to yellow stars will have one in the right temperature zone. Many will be tidelocked (one side always day) but many with more solar input than Earth are shaded by perpetual cloud over their noon-spot; worlds with less sunlight than Earth might still get enough in that high-noon zone; this effectively widens the range of acceptable orbits.
World-seas are a risk, and if you get one, with no land to weather and suck up CO2, climate's unstable and may eventually, as the sun heats, boil off your seas. But red suns change slowly. And subduction of water probably is stronger on high-grav worlds, so seas may not be outrageously deep.
Cowan doesn't mention this, but a planet's history of collisions can alter its water content a lot, too. Earth may already BE a super-Earth, so to speak--bigger than optimal, but the collision creating Luna would have stripped proto-Earth of excess water & gas that might have made it a second Venus or a hot worldsea. Even if not, and Earth really is right in the middle of the healthy size-range, Cowan ignored worlds smaller than Earth (understandable since we can't detect them yet). Yes, in our solar system there's a big mass-gap between Earth/Venus and Mars (8:1), nearly as big as between gas giants and rocky worlds (14:1), but there's no reason to think mini-Earths are rare. And if worlds down to half Earth's mass are viable (and I'm sure they are) that might triple his already high figure. If worlds one-fourth Earth's mass are (and I think THAT very likely) perhaps ten times as many--most stable stars would have at least one suitable world; some may have two.
Of course, not every planet with the right mass and temperature will flower. Radiation levels, chemistry, geology and even geography matter (the waterworld problem). And good worlds have lots of off days; Earth's only had intelligent critters for the last few percent of its history.
But in this galaxy, the rough number of worlds with smart megafauna does seem likely to be a few billion to many billion, with maybe a million civilizations--pretty much what the dream concluded! Like I said--funny mix of shamanism and low-tech science.
So the next time YOU hear a crazy shouting nonsense in a crowd... don't be sad. Not all us crazies are lost souls. Some are just shamans doing a low-budget spare-time survey.
And apparently--though I didn't know it--I'm one.
(To right: a range of alternate biospheres from 0.04 Earth masses up to 7+; click each for a tour.)
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