Why do guest-started threads get guest replies but member threads don't?

[Redbelly98]

I'm just curious about some of the postings in here that are by non-members, i.e. "Guests". Are these posts from some other site that are getting routed over to here?

It seems that threads that are started by a Guest will often have responses from other guests, whereas threads started by a member never have Guests' replies.

Just wondering about the inner workings of how PF operates, that's all.

p.s. here is an example of a "Guest thread", in case anybody wonders what I'm talking about:
https://www.physicsforums.com/showthread.php?t=239760

 

[Doc Al]

That forum, sci.physics.research, is a usenet forum and is not really part of PF--we just have an interface to it. PF members can post to it, but most of the posters to s.p.r. are not PF members and did not post through PF. That's why they show up as "guests".

 

[Redbelly98]

Ah, I hadn't noticed that these were all showing up in the same sub-forum. Thanks!