Realistically, might I be able to make meaningful contributions do these fields as a part-time amateur? Logically? yes. Realistically? Most likely not because

Realistically, might I be able to make meaningful contributions do these fields as a part-time amateur? Logically? yes. Realistically? Most likely not because scientific fields are shared human endeavors, share human endeavors are undertaken by communities, and for better or worse you are not a member of those communities. So you are not connected to the pulse of problems people within the communities are currently interested in and don’t have relationships that will get your papers read by members of the community. Only freshmen get the benefit of the doubt when it comes to endless September. On the other hand, publishing your work is as simple as wordpress.com or Youtube. So if the work is important to you, there are no meaningful impediments to putting it out there. People might not care, but if the work is meaningful to you that won’t matter. Of course, the simplest way to join the community is to do the things the community expects of its members…grad school. Good luck.