Another Earth?

A few years ago, during the course of a pre-university preparation week, I took part in an Arts vs Sciences debate. (I say 'took part', I was one of the 90% that, never having debated before, stood at the back trying to avoid participation of any sort). But during the course of this petty intellectual squabble one argument stands out in my mind:.
"Art simply poses questions. It is up to science to answer them."
     I think the reason this stuck in my memory like gum to a shoe was because I was so opposed to it. When, I thought, has art ever given science a helpful push in the right direction? Was it only with John Milton's Paradise Lost that Newton could invent his law of gravitation? Did Picasso's 'Blue period' inspire Einstein to create the special theory of relativity. Could Stanley Kubrick's 2001: A Space Odyssey have led to our knowledge of black holes. The answer, to me, seemed to be a resounding No. Art kept to its corner of society, science kept to ours.

But today a piece of art set my mind rolling along avenues usually reserved for scientific thinking. The inceptive art piece was a trailer for an independent movie released in October called 'Another Earth'. The plot is set around the fantastical premise that a second planet Earth has appeared in the solar system, and on it is contained a carbon copy of all human life, including ourselves. Ok, so at first the idea of a planet cloning itself seems a little wacky, and I would completely agree. But it led me to think -how impossible would it be for two habitable planets, orbiting each other to circle a star such as our sun? Could there be a planetary system, somewhere, with two Earths?

Many bodies in the universe orbit each other in binary partnerships. Most stars are thought to have stellar companions formed when gas collapsed under their own gravity. Some of these binary systems such as Mizar and Acrux can be seen on clear nights. A handful of asteroids have been found that orbit each other as they slowly move about the sun. The dwarf planet Pluto and its large moon Charon are also often called a double planet system. This is because Charon, weighing in at one ninth of the mass of Pluto, orbits a combined centre of mass that lies between it and Pluto. But how about Earth-sized bodies?

Just like in art, original ideas are hard to come by in science - often it seems like everything interesting has been done. However, despite many discovered binary systems, a quick journal search for binary planet formation shows almost no results! Exploring whether these equal-mass double-planet systems are possible would not only be incredibly interesting, but also could become testable as more and more exoplanets are discovered. In fact, the detection of a binary exoplanet might even put to rest one of the longest standing arguments in planetary science - whether large, Jupiter-like planets formed by gravitational instabilities (which, being similar to star formation, might create binary systems) or by accretion (which wouldn't). They might also help explain why planets have been found wandering freely through the galaxy, as it might be easier for binary planets to destabilise and be thrown from the solar systems.  'Three-body problems' are extremely complex, however, and the interaction of the sun and with other large planets may make such systems impossible.

Despite my previous opposition, bouncing scientific ideas off art can generate interesting and unproven results. So maybe, just maybe, art has a use after all...