If you don't have the fundamental knowledge, perhaps either stop reading the posts (or keeping reading the posts but don't contribute comments if you don't feel like you have the know how to contribute), OR go and get educated by reading up on the fundamental knowledge needed or taking an general extension course in chemistry and physics, etc if you want to participate.

Nobody is expected to know everything. You don't need to announce to the world that you don't know something. In fact, there is an assumption that if you don't voluntarily post any comments, that you don't know enough about the topic to discuss about it (or just don't care about it).