I had a high school physics course; actually two semester-long ones. I didn't get much out of it/them. That was in the 1970s. In the 1990s I bought Stephen Hawkings' A Brief History of Time: From the Big Bang to Black Holes. I started it, couldn't finish. Only read about 15 pages. It was a combination of too 'dry' and a bit over my head. I hadn't been exposed to any of the concepts in any but the most superficial way and it was easy to just toss it aside.
Last night I picked it up again. (I found it on top of a stack in a box in my storage locker and brought it upstairs, earlier in the week.) I opened to the table of contents. Chapter 4: The Uncertainty Principle. I remembered we had talked about that in my Physics 107 class, Fall semester, 2008. And that I didn't really get it, then, or remember anything about it now, other than the name Heisenberg goes with it. (I guess you could say I was uncertain.)
So I flipped to page 53 and started reading. OMG! I understand it now! And I only read three pages! WTF? Not only that, it shed new light on something else that had mystified me when I heard it referred to, at least three times over the years, that being the idea that the observer has an effect on the observed.
Obviously that idea makes sense if we think about humans behaving in a certain way if they feel 'unobserved' and a different way if they know they ARE being observed. But sub-atomic particles? How could they know they were being observed? They can't possibly, right? So what gives?
I see the rest of the chapter includes the 'two-slit experiment.' I have never understood that, either, and I hear that it isn't actually explainable, yet. But I think I'll read Hawkings' explanation. Do you think, maybe ... ?