I'm not sure what exactly you mean by theoretical science, to be honest. It sounds like a misnomer to me.
Theoretical science as in quantum physics, for example. It's theoretical because it's not practical by itself. It's not always factual, it's just fanciful thinking with logic applied.
Theoretical science, to me, is being open to things that will probably be left unknown in our lifetime or may never be known at all, such as what is on the other side of black holes. There is no factual data, only fanciful logic to support it. A "What would happen if..." scenario that has no definite conclusion.
I've found that they can be philosophical, but you have to be really sneaky about getting it into their lives. The best way is to make it relevant to them. They don't see how it's relevant to their lives because it isn't immediately obvious how it can be applied. So you take them around in real life, and show them working examples of things we have that stemmed from philosophical understandings (but just explain it, don't let them know it's related to that at first or they'll shut down). Eventually they'll start to realize that these patterns of thought really are relevant to furthering our understanding of reality, and dispelling perceptual illusions. It can take quite a while, and you have to be patient with them, letting them do something else if they start to get bored.