theorem critical_mass_above_has_benefit {T ρ c d_sq J : ℝ}
(hc : 0 < c) (hd : 0 < d_sq) (hρ : ρ < 1) (hJ : 1 < J)
(hJcrit : criticalMassJ T ρ c d_sq < J) (hT : 0 < T) :
T < criticalFrictionReal J ρ c d_sq := by
rw [criticalFrictionReal_eq J ρ c d_sq hJ (by linarith)]
simp only [criticalMassJ] at hJcrit
have hcd : 0 < 2 * c ^ 2 * d_sq := by positivity
rw [lt_div_iff₀ (by linarith : (0:ℝ) < 1 - ρ)]
have := (div_lt_iff₀ hcd).mp hJcrit
nlinarithPaper 1c, Section 3: The Participation Game