This is the first — and probably last — in a series, Ask The Celestial Monochord, where readers get the answers they deserve, given that they asked The Celestial Monochord. A reader writes (without asking anything at all):
Just wanted to let you know about an article in the Sept.-Oct. 2007 issue of "American Scientist," p. 383: "Modern Cosmology: Science or Folktale?" by Michael J. Disney. I found it interesting because it agrees with my view that current theories do not form a stable paradigm, or, as I've said to people (who disbelieve me, of course), "In 20-40 years, the universe will no longer be expanding." I have no idea, of course, what theory will take its place.Well ... you're probably crackers, although I haven't read the article. I did take a few classes in the philosophy of science in grad school, though, so my crackers have something your crackers haven't got — a diploma, as Professor Marvel would say.
I see at least two ways that old ideas are abandoned in science. One happened to cold fusion. The idea is interesting for a little while, but sooner or later it just turns out to be BS, and is chucked overboard. You seem to be saying that will happen to universal expansion, and if so, I bet you're wrong.
There's another way, and there, you're almost certainly right. I think of the "spiral nebulae." They were noticed and listed and described alongside all the other fuzzy patches in the sky. Once it was realized that they were "island universes," like our own Milky Way except millions of light years away, they increasingly got called galaxies, but the full transition in both terminology and mental image took decades.
Then galaxies were thought of as nice patches of stars interspersed with some dust and gas. But as time went on, they came to be thought of as dense areas of dark matter, with stars and gas and dust just "floating on top." Today, a galaxy is no more stars and interstellar clouds than a pint of Guinness is bubbles. Probably, professional astronomers and younger amateur enthusiasts have trouble thinking about galaxies any other way.
It takes a historian of science to go back and try to recover exactly what people meant when they said "galaxy" in, say, 1970. A historian who shows that these "galaxies" have been abandoned might be widely regarded as a nit-picking dilettante among professional astronomers — a judgment that would have its own merits and limitations.
In any case, my point is that some scientific ideas suddenly go extinct, while the rest evolve into new ideas without most people really noticing. I bet universal expansion and the "big bang" (a term already used more in the company of cameras and microphones than other scientists) will meet the latter fate — as will almost everything in science. And that's one of the things that recommends science as a way of making sense of the world — its thinking simply grows up in response to new information.