Turn out the stars economist.com
[ meanwhile, off at the real outer limits of science, we got this amusing review of The Extravagant Universe: Exploding Stars, Dark Energy and the Accelerating Cosmos, By Robert P. Kirshner . Clip: ]
Running just below the main storyline is an undercurrent of philosophy. Scientists have long believed—or hoped—that the basic laws of the universe would be beautiful. They had in mind a simple, austere beauty, with an air of inevitability, like a sunrise or a short mathematical proof. Mario Livio's, “The Accelerating Universe” (John Wiley, 2000), dwells admirably on this topic. Mr Kirshner shows us that an accelerating universe is not beautiful. In the new scheme, so as to provide enough repulsion to match the observed acceleration, 70% of the universe has to be made of a mysterious substance that has been dubbed dark energy. Around 25% is dark matter, a different but equally invisible stuff, hypothesised to explain how galaxies have the proper mass needed to hold them together. Only 5% of the universe is made of ordinary atoms that compose stars, planets and everything on Earth.
That seems unduly complicated and downright ugly. Nor is this all. According to supernova measurements, acceleration began in astronomy's yesterday, only a few billion years ago. Why not at the start or trillions of years hence? Why now? That acceleration is occurring just as it is observable by humans smells of coincidence or contrivance. That is why, when a colleague first suggested that on the data there must be a universal repulsive force, Mr Kirshner felt repelled. “In your heart,” he told him, “you know this is wrong.” But, before long, the evidence swayed him. It seems the actual universe is less simple and less beautiful than the world mathematicians have dreamed of. The extravagant universe Mr Kirshner describes is gaudy too. |
