Monday, 20 October 2014

That's No Moon

Mimas, everyone's second-favourite moon, has been found to have an unorthodox wobble that is too big for a moon that size with a solid internal structure.  The authors of a paper in Science offer two explanations: that it has a rugby-ball-shaped core, or that it has an internal liquid ocean.  This is a great example of hypothesis generation, which is both a key part of analysis, and risky and difficult.  It is a fairly straightforward matter (assuming you know about moons and gravity and so on) to work out that the observed wobble isn't consistent with a solid core.  It's quite another matter to come up with possible hypotheses that are consistent with the evidence.  Not least, this is because (as a matter of logic) there are an infinite number of hypotheses that could account for any given set of evidence.  This means that there is no algorithm that can exhaustively generate all the possible explanations for a set of data.  How humans do it is still a matter for debate and undoubtedly one of the most impressive features of our cognitive architecture.

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