Life, Unbounded

Life, Unbounded

Discussion and news about planets, exoplanets, and astrobiology

Cosmic Citizens


More interesting than the weather (Credit: Steve Jurveston)

Our remarkable species has existed in its present form for about 100,000 years. That's about 0.0025% of the total time that we think life has existed on this planet. We, and the vast network of life around us, occupy barely a couple of percent of the volume of this world - its surface, a few kilometers into its subsurface, and some way up into its tenuous atmosphere. The Earth is an end product of the agglomeration of the equivalent of about a trillion kilometer-sized planetesimals that themselves coalesced from the sticky microscopic dust of a proto-planetary disk some 4.5 billion years ago. Altogether that represents about 0.003% of the total mass of that original smear of dust and gas that stretched from a youthful Sun to far, far beyond the orbit of Pluto. Today the Earth occupies about 0.0000000000000003% of the volume of space encompassed by a sphere just large enough to contain the orbit of Neptune. And it would take more than 4,400 of those spheres lined up edge-to-edge to reach the nearest star system and the nearest known exoplanet of Alpha Centauri B.

Our Galaxy, the Milky Way, contains at least 200 billion stars. Seventy-five percent of these stars are not individually visible to the naked human eye, they are too small and faint - smaller and fainter than the Sun. The nearest large galaxy to us, Andromeda, is about 2,700,000,000 times the diameter of Neptune's orbit in distance, and is moving more or less directly towards us at nearly 70 miles a second. It contains about a trillion stars and will come lumbering into the Milky Way in about 4 billion years time.

Beyond this small cosmic patch lies a 13.7 billion year old universe containing as many as 400 billion galaxies and more than 10,000,000,000,000,000,000,000 stars and perhaps at least as many planets. In a few hundred billion years the accelerating expansion of space will isolate all these galaxies, stretching the light passing between them to such an extent that no observer in any one galaxy will be able to see the others.

And that, dear reader, is pretty much that.

We are, I'm afraid, an unfathomably microscopic presence amid all of this. But this is our lot, our serving of existence. We can ignore it, we can rail against the injustice of it, and we can invent reasons to disbelieve it. Or we can embrace this vast cosmic wellspring for what it is, our home.

About a week ago I participated in the BBC World Service's radio show The Forum, talking about black holes, galaxies, and some of the fascinating peculiarities of this universe. I was also asked to come up with a "60-second idea to change the world". Imagine, said the producers, that you're president of the planet and that you can address something that bothers you or that you think would make the world a better place - radical or controversial, or just plain unexpected.

Eventually, after much pacing and gnashing of teeth I came up with this (download here)

The essence of the 'big' idea is actually pretty simple (and more serious than it might appear). Let's treat our cosmic environment with the same level of seriousness as we treat all the ordinary stuff right under our noses. And let's incorporate it into the fabric of our children's education and our own lives. At school we're taught grammar by learning about trees, cats, dogs, clouds, cars, and bicycles. We learn algebra with dull exercises about buying candy or sharing apples. Why don't we do all of this with reference to asteroids, comets, planets, moons, stars, interstellar space, and galaxies? We can also count the moons of Jupiter, the craters of Mercury, the rings of Saturn and the number of stars in the sky. In doing so we'd instill a basic knowledge of our cosmic environment, bringing it to earth, into view. Adults could do the same. Stop making small talk about sports events and discuss something really big and important; supernova, life on other worlds, the fate of the universe. Don't be bashful.

Why? Well, right now we are dusty little hominids in an unspeakably tiny bit of the universe, and unless we get a proper perspective this may be how we remain. A ready vision of our cosmic existence would help. It might make it just a little easier to be better behaved with each other, be more conscious of our species' needs and the multitude of natural dangers facing us across not just years but millenia and eons. Maybe, just maybe, we'd think a little bigger and find some ways to extend humanity's use-by-date by stepping out into the void.

In other words, by doing nothing more than applying our remarkable brains to learning a few more facts about the universe around us we might inch a little way closer to true cosmic citizenship. A simple act that could carry us to eternity as well as make our present lives so much better.


The views expressed are those of the author and are not necessarily those of Scientific American.

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