How did you go about learning this?
I have had Feyman's lectures sitting on my bookshelf for well over a year now, and hope it won't always be in my "someday" bucket.
I have had Feyman's lectures sitting on my bookshelf for well over a year now, and hope it won't always be in my "someday" bucket.
After that I turned to more 'big picture' stuff to try to at least get a survey of the breadth of knowledge. Like you mention the Feynman Lectures are great for this. You can also find them online [1] which may be more convenient. "A Brief History of Time" is also a phenomenal big picture look at cosmology, which is my current primary interest.
Perhaps the best resource of all, and what I'm currently working through, is Leonard Susskind's "The Theoretic Minimum." I first saw this as a book. It's essentially a physics overview intended for those with a solid mathematical background, but without much formal education in physics. The book is excellent, an even better resource for this is the site [2] for it. It has extensive coverage and lectures on all major topics. The only downside is the lack of questions or material to test your understanding.
Ultimately, I think the most important thing is to find something that draws you in. From there everything is easy. Take a weekend sometime and really dig into something that fascinates you. Time dilation in general, the twin paradox, black holes and their funkiness at the event horizon, the two slit experiment in quantum mechanics, etc. These are all things with massive amounts of information available that can really draw you in.
[1] - http://www.feynmanlectures.caltech.edu/ [2] - http://theoreticalminimum.com/courses