A short history of nearly everything - Bill Bryson [85]
Recent evidence suggests that not only are the galaxies of the universe racing away from us, but that they are doing so at a rate that is accelerating. This is counter to all expectations. It appears that the universe may not only be filled with dark matter, but with dark energy. Scientists sometimes also call it vacuum energy or, more exotically, quintessence. Whatever it is, it seems to be driving an expansion that no one can altogether account for. The theory is that empty space isn't so empty at all—that there are particles of matter and antimatter popping into existence and popping out again—and that these are pushing the universe outward at an accelerating rate. Improbably enough, the one thing that resolves all this is Einstein's cosmological constant—the little piece of math he dropped into the general theory of relativity to stop the universe's presumed expansion, and called “the biggest blunder of my life.” It now appears that he may have gotten things right after all.
The upshot of all this is that we live in a universe whose age we can't quite compute, surrounded by stars whose distances we don't altogether know, filled with matter we can't identify, operating in conformance with physical laws whose properties we don't truly understand.
And on that rather unsettling note, let's return to Planet Earth and consider something that we do understand—though by now you perhaps won't be surprised to hear that we don't understand it completely and what we do understand we haven't understood for long.
12 THE EARTH MOVES
IN ONE OF his last professional acts before his death in 1955, Albert Einstein wrote a short but glowing foreword to a book by a geologist named Charles Hapgood entitled named Charles Hapgood entitled Earth's Shifting Crust: A Key to Some Basic Problems of Earth Science. Hapgood's book was a steady demolition of the idea that continents were in motion. In a tone that all but invited the reader to join him in a tolerant chuckle, Hapgood observed that a few gullible souls had noticed “an apparent correspondence in shape between certain continents.” It would appear, he went on, “that South America might be fitted together with Africa, and so on. . . . It is even claimed that rock formations on opposite sides of the Atlantic match.”
Mr. Hapgood briskly dismissed any such notions, noting that the geologists K. E. Caster and J. C. Mendes had done extensive fieldwork on both sides of the Atlantic and had established beyond question that no such similarities existed. Goodness knows what outcrops Messrs. Caster and Mendes had looked at, beacuse in fact many of the rock formations on both sides of the Atlantic are the same—not just very similar but the same.
This was not an idea that flew with Mr. Hapgood, or many other geologists of his day. The theory Hapgood alluded to was one first propounded in 1908 by an amateur American geologist named Frank Bursley Taylor. Taylor came from a wealthy family and had both the means and freedom from academic constraints to pursue unconventional lines of inquiry. He was one of those struck by the similarity in shape between the facing coastlines of Africa and South America, and from this observation he developed the idea that the continents had once slid around. He suggested—presciently as it turned out