Who’s Out There? A Problem With Numbers3 min read

When we think about possible life in the universe, we soon encounter numbers. There’s too many of them, both large and small. We simply can’t grasp how huge or how small they are, especially the numbers of microbes
that may be lurking in many different places in our solar system.
The nearest star in our galaxy of 100 billion stars is about four light years away. That’s 252,600 astronomical units. Voyager is cruising along at 3 au/year, so it would take 84,200 years to get to our nearest stellar neighbor, whether or not it had any hospitable planets. Such distances are hard to imagine until we get real about the time it would take us to get there, even at a reasonable fraction of the speed of light. And there are how many other galaxies? 100 billion or so? And the nearest one is how much farther than the nearest star in the Milky Way?
To get a better idea about large numbers, consider the human brain. Science News November 30, 2013 tells us we have 86 billion neurons in our brain. (There are also three types of Glial cells that nourish, insulate and protect those neurons, but we’re not counting those.) Each neuron can have as many as 10,000 connections to other neurons. 10,000 x 86 x 10 billion is a huge number of connections, which is why students of complexity say it is the most complex object in the universe. Galaxies with their 100 billion stars are simple in comparison. No wonder we get into such trouble.
In thinking about life out there, let’s start with ourselves. Who do we think we are, compared to who we think might inhabit outer space? When I was studying medical microbiology , we focused on a few viruses that were causing trouble—polio ,flu and the common cold, hepatitis, rabies and some others. Now, suddenly we have discovered that 67.7% of the DNA sequences found in our blood plasma belong to viruses. Only 3.6% are human and 9.5% are bacterial. The rest are a mystery. (See Popeorgiev et al in Journal of Infectious Diseases 2013.) We are loaded with microbes.
We carry around lots of common disease viruses, plant disease viruses, and bacteriophages. The latter are viruses that infect the huge numbers of bacteria that inhabit our bodies. They help determine which bacteria will populate our guts. Phages mutate rapidly, and bacteria can use them against other bacteria or against us if they help the nastier bacteria make toxins or resist antibiotics.
The point of all this is that our resident microbes form a wild microworld we couldn’t live without—which should give us a notion how complex life on other moons or planets could be. Most likely, most life out there will be microbes like viruses.
Small and simple critters probably evolved first, if we suppose that simple design had to precede organisms more complex. Hence viruses—like other microbes—could be the most common type of life on Enceladus or Europa or the billion or more Earth-like planets in our Milky Way galaxy.
Viruses are very small packets of clever protein wrapped around DNA. Bacteria are huge in comparison and much more complex, with their tiny organelles, cilia and other contraptions like cell walls. But they have no nucleus, as do the much larger cells that make up our body tissues. By the way, bacteria outnumber the cells in our body by ten to one. They reproduce on their own, unlike viruses, which rely on cells or bacteria to produce their DNA offspring. Viruses outnumber the bacteria in our body ten to one.
There are 10 quintillion (1018) viruses, more or less, on Earth. And they’re everywhere. We depend on them for all kinds of physiological reasons. So does all life on Earth, probably. If life got a foothold on some other moon or planet in our solar system, we shouldn’t let it surprise us with its versatility, its tinyness and its huge numbers.
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Cary Neeper is an avid student of complexity theory, sustainability, steady-state economics, and the impact of cosmology on issues of science and religion. She grew up in the foothills of Hayward, California, where she helped rack dried fruit on her father’s 40-acre apricot ranch. After studying zoology/chemistry and religion at Pomona College and medical microbiology at the University of Wisconsin, she moved with her husband to northern New Mexico, where they raised their family. The Neepers still live in the Southwest with a friendly menagerie of dogs, fish, chickens, geese, ducks and a turkey called Little Bear. Cary plays string bass with local folk, symphony and jazz groups and tennis with local retired physicists. She paints landscapes in acrylics, including the cover art for her first Penscript title, The Webs of Varok. Cary's first novel and Webs of Varok prequel A Place Beyond Man was originally published in 1975 by Charles Scribner’s Sons, Dell, and Millington, London. Cary re-released A Place Beyond Man as an Author’s Guild Backinprint edition, now available from online booksellers. Its themes of sustainability and interspecies cooperation have now grown into new adventures for its human, elll and varok family as they travel the alternate 21st century Solar System in the five-volume Archives of Varok, coming from Penscript Publishing House in 2012–2014. Cary’s other works include two musical science fiction comedies “U.F.F.D.A.!” and “Petra and the Jay,” as well as newspaper and magazine articles, essays, short stories, and book reviews for The Christian Science Monitor.

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