When you get into what diffraction actually is, you learn that it is not actually "caused" by anything. Diffraction is an intrinsic trait of light that exists within the wavefront. It is often described as the "bending" of light caused by it's encounter with an obstruction or an opening. That's a useful description to describe the effect of what is happening, however sadly it is not actually an accurate description of what is actually causing the effect.
Diffraction happens with waves and one method that we use to model light's behaviour is to say that in some circumstances it behaves like a wave. Diffraction is not an intrinsic property of light at all, it is a trait of waves and how waves behave.
Please stop spreading bad science.
I'm sorry, but I beg to differ. Here is an article that details the actual science of what a diffracted wavefront is, how diffraction in a wavefront presents and behaves, :
You don't know what you don't know and you're just using a random web article that happens to provide a theory that makes sense to you.
Answering your questions is beyond my ability, schooling or training.
Go find a course on physics that teaches about light and learn about it the way professionals do. An astronomer does not learn about physics from the web. Articles on the web greatly simplify things.
That isn't a random web site. I found that site years ago (probably before I ever even started posting on these forums) while researching optics for photography (I think that would make it even my pre-DSLR days, as I like to research concepts, theory, equipment, brands, etc. before I buy anything.) I pulled that site out of my bookmarks, bookmarks that I've been stringing along from Opera version to Opera version for years.
It's one of the best web sites on the net that covers this stuff in as detailed, specific, mathematic, and scientific a manner as you can find, too! I seriously challenge you to find a better resource than that that explains the concepts better, or more correctly. And it is FAR from "simplified". Did you even check it out, did you actually look through the site at all? Do you know how much science and mathematics is used in that site to explain the concepts of optics, refraction, reflection, diffraction, and every other aspect of telescopes? It's riddled with math and complex theories, the same exact theories I LEARNED IN MY PHYSICS CLASSES IN COLLEGE.
My knowledge doesn't come only from the web...the web is simply an easy source for reference when one is trying to back up their arguments with hard facts (something I have done plenty...I still don't see any references from you to back up anything your saying.) I've got my old college physics books on my bookshelf here, right alongside, um, oh yeah, Feynman's QED (fantastic book, that.) I also have Newton's "Optiks" on the same shelf, as a nostalgic historical reference and read.
I guess I should have expected you to try and refute hard science. I do challenge you to actually read the site, instead of simply assuming it is unscientific or otherwise flawed simply because I'm the one who posted the link. You might actually learn something, find it edifying.