Living on the real world: We’re Earthlings, till death do us part.

“Reality is that which, when you stop believing in it, refuses to go away.”                                                               

sometimes attributed to Philip K. Dick, in “How to Build a Universe that Doesn’t Fall Apart Two Days Later”

Yesterday’s reality? Our propensity to argue. Here’s another reality – quite different. Arguably (there’s that word!), we basically don’t live in the real world as much as we live on it.

Think about it. The Earth is some 8000 miles in diameter. But human activity for the most part is confined to the skin of this Earth; the very thinnest sliver right where the earth and its waters meet the sky. This is a narrow region between 40,000 feet above the Earth’s surface – flight altitude – and maybe a few thousand feet below that same surface – the depths we mine. And except for the flying public (100 people per plane, say, on 30,000 2-3-hour flights per day, so that maybe 300,000 of us out of seven billion are airborne – one out of every 20,000 people – at any given moment) and those few working in subterranean mines, all of us are really spending our entire lives within a few feet above or below the Earth’s surface. The same thing is true of virtually all plant and animal life. And we’re influencing planetary processes only to the extent we’re impacting this very thin skin of the planet. What we see as an absolute hubbub up here has yet to be felt at the Earth’s core…)

This thin skin is totally unlike the Earth a few feet further down, or the air a few feet higher. The rock and soil themselves are best thought of as the slag or dross that floated to the surface as an initially molten planet cooled billions of years ago. The composition of this outermost crust differs noticeably from the minerals at depth, in part because of geologic processes, and in part because of the effects of biota, working the rock into soil over a period of a few billion years. The planetary skin is (patchily) covered by the merest hint of a vegetative and animal slime…marshes or grasslands or woods. Much of it is bare sand or rock.[1]

Ready for more reality?

We (essentially all seven billion of us) are stuck here – not just here on Earth, but here on the merest sliver of the Earth’s crust. We’re not going to be able to live anywhere but on this thin skin of the Earth anytime soon. Start with drilling downward. The best science we have suggests that temperatures increase 25-30 degrees Celsius for every kilometer of depth; the deepest mines in the world as of this writing extend no more than 4km (2.6 miles) beneath the surface. The heat is unbearable, pressures are enormous, accidents are a way of life, and of death. Not a good way to go.

How about going upward and outward? By dint of special effort we periodically launch a handful of people into a temporary orbit. By more effort still we could return to the Moon, but not in any kind of circumstance that would enable any number of us to stay there indefinitely, or become in any sense of the word independently self-sustaining.

As for human colonization of the planets, fuggedaboudit – at least for now. Take Mars. At its closest, Mars is 30,000,000 miles away, more than 100 times as far as the Moon. The Moon is just a few days’ journey distant; getting to Mars with today’s technology, or that on the horizon, will take many months. Mars’ atmosphere is about 1% the density of our atmosphere – essentially a vacuum. What air there is, is mostly carbon dioxide. Nobody’s living on Mars except under spacecraft-like conditions, and no large numbers will be living there over any historical interval that we might care about. (Human settlement of other worlds is not about sending us out there wholesale; it’s about sending out very small numbers…and hoping that their efforts somehow take.) Space is largely empty. The distances are vast. You’re an astronaut? Our hearts and prayers are with you. We want you to succeed! As for the rest of us? For better or worse, in sickness and in health, until death do us part, we’re Earthlings.


A conversation with my research-mathematician father in 1975 or thereabouts brought this point home. I was living in Boulder at the time, and during a visit I was enthusiastically reporting to him that the University of Colorado had just built a new planetarium on campus, next to the astronomical observatory. To engage the public, they built a scale model of the solar system outside. They had a ball about the size of a basketball that represented the sun, standing next to a plaque giving a few basic facts. Several feet away was a bb pellet, representing Mercury. Some distance further was a pea-sized sphere and a little sign giving a few facts about Venus. And so on, out to the small sphere representing Pluto (it was still considered a planet in those days), about a quarter mile away, way off by the CU Engineering Center. “And,” with a flourish, I’m telling my Dad, “to scale, the nearest star would not be in Boulder, but in Harvard Yard!” “Yes,” my Dad answered, without batting an eye. “That’s why astronomy is so uninteresting.” This from a science junkie – a member of AAAS, a fellow of the American Statistical Association! Which, you might say, brought me back to reality – and down to Earth.


Till death do us part? If we’re wedded to the Earth, and divorce is not an option, maybe as a human race we ought to do what married people do…learn as much about our spouse, and his/her needs, as we can; be attentive to changes, maybe even anticipate, head off problems, rather than being oblivious. More on that in the next post.

[1](pointy-headedness alert!) Mathematicians refer to such geometries as “sets of measure zero.” So, relative to the 3-D sphere, the Earth’s surface is a set of measure zero. And, on that outer surface, the world’s coastlines are a set of measure zero relative to the vast expanses of land or sea. That’s the reasons why human impacts are so great on something as massive and imperturbable as the Earth, and, in turn, why the world’s coastlines are uniquely vulnerable.

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4 Responses to Living on the real world: We’re Earthlings, till death do us part.

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