Charles Townes recalls the day he invented the maser

Interviewed by Finn Aaserud, 1987

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We'd had enough meetings that we had really surveyed everything that was going on, surveyed our own ideas. And so I was beginning to feel that, well, we may be coming to an end as to what we could usefully do immediately. And I was a little discouraged that nobody had turned up... what I felt were new and promising ideas. There were new things, but there was just no clear solution. Then we were having a meeting in Washington. That was the occasion when I sort of tried to think back over things, and what it was that might, might possibly work, and why other things weren't working. And that was where the possibility of the maser occurred to me...

It was in the early morning, before that last meeting, that I was sitting in the park and just thinking it over, with a little bit of a sense of frustration, how we hadn't gotten anywhere, and why was that? The fact that I had surveyed all the field and thought about it overtly and hard and gotten everybody else's ideas, and they had surveyed it and thought about it too, and there weren't any ideas, certainly was part of the reason I decided, "Well, we have to do something drastic. And really, these are the problems, why it hasn't been working. We've got to just find some way of getting around those problems." And the problems were in part just making small things. [There was] already my interest in molecules, and my thoughts back at the Bell Labs about possibly using them as circuit elements. We said, "Well, gee, if you're going to make some small things accurate, that's molecules and atoms are the ways of doing it." But the trouble is, they don't give much energy. And then it suddenly occurred to me: "Well, in principle, they could [produce more intensity] if you get a temperature inversion." And how do you do that? And I just followed up those ideas. So that it was a situation which helped bring about my facing the problem and deciding, well, this is the only way it's going to be done, if we can do it. So in that sense it came out of the committee.