I think this guy says it pretty good. Be sure to read the rest of his blog at the link. It's a NASA blog.
Wayne Hales Blog - nasa.gov: Predictions and WishesAt a recent speaking engagement, I was introduced as an “expert”. Scary title, that. At another place I was introduced as "highly experienced" which is a polite way of saying "old".
These put me in mind of Clarke’s Law. Sir Arthur C. Clarke, the inventor of the geostationary satellite, author of innumerable books both non-fiction and science-fiction, and one of the truly forward thinkers of the 20th century. Clarke’s first law has to do with predictions and experts. He came to an interesting conclusion after studying the predictions of experts over the previous centuries. To get you in the right frame of mind, consider some of these real predictions by well respected experts of the past: