theorem susceptibility_exponent_one (sigma0_sq T Tstar : ℝ)
(hTs : 0 < Tstar) (hT : T < Tstar) :
varianceAtFriction sigma0_sq T Tstar =
sigma0_sq * (1 - T / Tstar)⁻¹ := by
rw [intensification_rate (by linarith) (by linarith)]
rw [one_div]Phase Transition at T* (Gap #8)