How do you identify an emerging investment theme before it becomes obvious?

Hello, I’ve been thinking about how do you actually discover new investment themes early. Not individual stocks, but a broader theme that may eventually become significant, for example - data centers, nuclear energy, robotics, defense modernization, etc. I’m curious how you personally approach this?And one you notice a potentially interesting theme, how do you figure out which companies are actually exposed to it?
I’m particularly interested in the process before a theme becomes widely recognizable. What does your research look like at that stage? Thanks

To clarify, I’m not asking how to predict which stock will go up. I’m more interested in the research process around identifying a developing industry/theme and then figuring out which companies are actually exposed to it. For example, if you noticed the early development of data centers as an investment theme how do you go about mapping companies and sub-industries benefiting from it?