Besides being fascinating in its own right, such exotic finds are a good test of astronomers’ theories about how planets form. In PH1’s case, its four stars are actually a pair of binaries. Conventional planetary-formation theory holds that worlds condense out of a disc of dust and rubble early in a star’s life. But in this case, “the second binary would sit right at the edge of the protoplanetary disc,” notes Dr Lintott. Computer models suggest that the gravitational influence of the second pair of stars ought to disrupt the disc and prevent the formation of planets. Reality, in this case, disagrees with the models—and that is how science advances.
Source: The Economist's "Babbage" blog, in a post on exoplanets
(Of course, science advances when reality agrees with models too.)
Edited to remove "emphasis added" from the quotation, which I had added originally but have since decided against.
As we learn more and more about the solar system, the reality-check that our theories have to pass becomes more and more stringent. This is one reason why scientists have a habit of opening up old questions that everybody assumed were settled long ago, and deciding that they weren’t. It doesn’t mean the scientists are incompetent: it demonstrates their willingness to contemplate new evidence and re-examine old conclusion in its light. Science certainly does not claim to get things right, but it has a good record of ruling out ways to get things wrong.
-- The Science of Discworld, Terry Pratchett, Ian Stewart and Jack Cohen
Here's the new thread for posting quotes, with the usual rules: