The ultimate implementation of Ideal Money is not a medium per se but a metric. However it is not a transmuted metric, for example, of the kilogram, as Nash alludes to, but rather more a replacement for it (and all existing metrics).
That is the secret Nash hid.
And the formulaic implementation of it belongs in E=MC2 as Ideal Money is the description of the asymptotic evolution of our medium of exchange into pure (ultra transferable) energy, or effectively energy described through (not over) time (ie duration).
From here, there needs to be a redefinition/understanding of our brains vs our minds or (w/transmutation) our individual consciousness vs our collective consciousness (also relateable/comparable to the observer/analyzer issue we are conditioned to hold dear to) in order to proceed with the implications of the levation of Ideal Money as a universally stable metric (for ALL time).