The idea of this roadmap is, in some sense, to turn the traditional roadmap upside down. Instead of starting with only approximately correct theories (Classical mechanics, Classical electrodynamics) and then slowly moving toward the more correct ones (Quantum Mechanics, Quantum Field Theory), here we start with the best theories of nature that we have.

The modern theories can be derived straight-forwardly from the principles of special relativity and using symmetry arguments. The older classical theories can then be understood as approximations of the modern theories.

One advantage of this approach is that less time is spent on only approximately correct theories, and more time on the best theories of nature that we have. In addition, this approach show the connection between the various theories clearer than the traditional approach.

Crucial puzzle pieces that are missing in the above roadmap are mathematical tools. These are best learned when they are actually needed. This means, whenever you are trying to understand some topic like, for example, quantum mechanics, and a mathematical concept that you don't know is used, simply learned it then.

Here is a (incomplete) list of mathematical tools that are crucial for the topics listed above:

• Vector calculus: basis vectors, change of coordinate systems, matrix multiplication, scalars, right-handed and left-handed coordinate systems
• Calculus: product rule, integration by parts, Taylor series expansion, series, index notion, Kronecker symbol, Levi-Civita symbol
• Linear Algebra: conjugation and transposition of matrices, matrix exponential function, determinants, eigenvalues and eigenvectors, diagonalization of matrices.
• Misc: Fourier transform, Delta distribution

There is a book called "Physics from Symmetry", that tries to implement the roadmap outlined above. However, of course, additional books are needed to understand each topic mentioned here fully.