Samir’s Selection 02/17/2015 (p.m.)
Why Pluto is no longer a planet >>>
The immediate reason was that Pluto did not meet the definition of a planet that was formally agreed, for the first time, at the 2006 IAU meeting. To qualify, the astronomers decided, an object must be in orbit around the sun (so, for instance, Earth’s moon does not count, despite being considerably bigger than Pluto). It must be massive enough to have become spherical under the force of its own gravity (which rules out things like asteroids and comets). And finally, it must have “cleared its orbit”, either by absorbing other nearby objects into itself, or by kicking them out of the way with its gravity. That definition attempts to capture the intuition that planets should be the most notable features of solar systems after their stars. Pluto passes the first two tests, but fails the third. These days, it is clear that Pluto is merely one among zillions of “trans-Neptunian objects” (TNOs), itinerant hunks of rock and ice that drift around in the distant reaches of the solar system…
Pluto’s reclassification is a very public demonstration of the way science works: when new evidence emerges that overturns what was previously accepted, the facts prevail, and the accepted theory is overthrown in favour of a new, more accurate understanding of the universe. Science is based on evidence, not dogma. And those with a sentimental attachment to Pluto who are still angry about the whole affair (and there are many, including some professional astronomers) may take some solace from the fact that this is not the first time in history that something like this has happened.
What ISIS Really Wants >>>
by Graeme Wood
Economics and finance: The uses and abuses of history >>>
It is worth reflecting briefly on how a rigid interpretation of history has been mistaken in other areas; for example, the belief that World War Two would resemble the defensive stalemate of World War One, allowing the Allies to be overwhelmed by blitzkrieg; the subsequent tendency to blame appeasement for Hitler’s rise and thus for western governments to oppose all Third World nationalist movements on the domino theory, and so on.In short, it is tempting and can be thought-provoking to use historical analogies as long as one does not take the parallels too literally. History does not repeat itself exactly even if we know exactly (which we don’t) what did happen in the past.[Comment – quote] “In public policy, as in medicine, the real challenge is not in figuring out which remedies are the best solution to solve which problems, but diagnosing what the true underlying problem with the patient might be. Believing something to be a magic bullet is a sure way to failure, but it is important not to forget that it may still have its place.”
Posted from Diigo. The rest of my favorite links are here.