AMA | September 2024

7402.663 - 7422.983 Sean Carroll

Henry Jacob says, when you coarse grain a system, it seems analogous to block diagonalizing a matrix into a macro scale and micro scale component. This would mean the system is actually the product of two systems. However, most of the coarse grainings I've seen, e.g. in thermodynamics, are not of this form. It seems like we are simply ignoring the off-diagonal terms. Am I right?