I'm looking for interesting podcasts that I can listen to where fiction writers or scientists and physicists (Neil Degrasse Tyson and Michio Kaku come to mind) discuss sci fi topics. For example, space travel, lazer beams, terraforming planets, energy fields etc.
Maybe not what you're looking for, but Harry Potter and the Methods of Rationality may be worth a listen. It's a high quality reading of a well-know Harry Potter fanfiction that delves into science, rationality, fantasy and scifi tropes, moral issues related to sci-fi and fantasy, humanism, cunning plots, and more. There are also a few essay and interview episodes mixed in there as well. Link: http://www.hpmorpodcast.com/ Leo Laporte and company did a predictions podcast that brushed on some of the issues you mentioned a while back. There were some very interesting discussions in that one, although the podcast was discontinued a few years back. They still have an archive of back episodes available though: https://twit.tv/shows/fourcast Writing Excuses is a good, general writing podcast that Brandon Sanderson and a few other writers do. Definitely worth checking out, but not sci-fi specific. http://www.writingexcuses.com/
Crash course is great. John and Hank green are very educated guys and a writer. Pbs spacetime is another good one, that guys actually a physicist. You may also try the Isaac Asimov debates, some of the topics might interest you. Everything I've mentioned are YouTube channels.