[DagAgren]

Many discoveries in physics have quite large timespans between being theorised to exist, and being actually detected.

Was it ridiculous to say those might exist?

[chmod775]

Well, most of the other theories back then would seem ridiculous and obviously wrong nowadays. That's the nature of theorizing when you have little information.

Obviously we mostly remember those theories that turned out to be right.

[DagAgren]

And how do you find out if they turn out to be right, if you dismiss them immediately as "ridiculous"?

That is not how science works. There are other ways of judging if a theory is worth exploring than just a "it must be testable right now".