axion

Well, axions were a very different kind of particle, quite different from anything before.

In subsequent years I was able to spin off one successful application of those ideas after another — or do other creative things like axions, though that was much later.

John Preskill, Mark Wise and I worked this out and discovered that in fact lots of axions get left over, and that they would have just the right properties to supply the “dark matter” that cosmologists seem to need.

The case for dark matter has become much stronger, and axions have become much more popular.