cepheid said:
No, but it would be seriously cool. Every author tries to keep re-inventing the wheel, thinking that their text will be the best and most self-contained to date (at least for the audience and purpose they are targeting).
One thing that people should be thinking about is how do textbooks work in the age of the internet. Wikipedia, for all of it's problems, is the closest thing that I've seen into seriously new thinking about how to set up a textbook.
It's not so much the authors, as the publishers. The reason that books are self-contained is that it fits well with copyright law. If you have a "diffused textbook", it's not clear who gets paid what and how. I'm sure someone is going to work it out.
It would be so much better if instead we could pool together related knowledge from a bunch of different sources, allowing one to build on one's knowledge incrementally without having to search endlessly to find out which book has the background you need to understand the current one that you're supposed to be reading. I think it's a neat concept.
The problem is that no one (yet) has figured out how to do this. If you have one person do it, then they are going to have to eat somehow, so you need a payment mechanism. You can try to crowdsource this, but then you have to figure out how to split up the tasks, and you have to figure out how to create an environment in which things "self-organize."
He spends one chapter giving a fairly perfunctory overview of GR, and then introduces the Friedmann equations in the next chapter. He states that they can be derived from the Einstein field equations for the case of an isotropic and homogeneous world model, but does not bother to do so himself.
That's one piece of advice that I'd give someone that wants a quick start to cosmology. Don't go too deep into General Relativity. Get a "hand waving" explanation for the Friedmann equations, once you have that then you can learn the physics concepts, and once you have that, then you can go back to the Friedmann equations, and look at the GR issues in more depth (or not).
If you want to get super-hand-wavy you can do cosmology is a Newtonian framework and then talk about how GR is different. This is useful pedagologically because a lot of the important features of cosmology are gravity model independent.
That's what the professionals do. Someone works out the basic equations and then this gives a framework that people can use to do calculations is a more or less Newtonian setting. Now whether to what extent that's a valid way of doing things is a topic you can spend a few years writing your doctoral dissertation on (it's called the backreaction problem). The thing is that it's a hard problem and even smart people can deal with only one hard problem at a time, so one tactic is to massively simplify the GR model so that you can go deep looking at something else. Dark matter or galaxy evolution for example.
One problem with going straight to Weinberg is that it's designed for graduate researchers who are going to be writing dissertations on the stuff. Once you get through Weinberg, then you'll be ready to start on your dissertation and start writing papers on cosmology.
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