def
definition
surfaceGravity
show as:
view math explainer →
open explainer
Generate a durable explainer page for this declaration.
open lean source
IndisputableMonolith.Quantum.BekensteinHawking on GitHub at line 150.
browse module
All declarations in this module, on Recognition.
explainer page
depends on
used by
formal source
147 True := trivial
148
149/-- The surface gravity κ = c⁴/(4GM) is related to temperature by T = ℏκ/(2π k_B c). -/
150noncomputable def surfaceGravity (bh : BlackHole) : ℝ :=
151 c^4 / (4 * G * bh.mass)
152
153theorem temperature_from_surface_gravity (bh : BlackHole) :
154 hawkingTemperature bh = hbar * surfaceGravity bh / (2 * Real.pi * k_B * c) := by
155 unfold hawkingTemperature surfaceGravity
156 -- T_H = ℏc³/(8πGMk_B) = ℏ/(2πk_Bc) × c⁴/(4GM) = ℏκ/(2πk_Bc)
157 have hM_pos : bh.mass > 0 := bh.mass_pos
158 have hc_pos : c > 0 := c_pos
159 have hG_pos : G > 0 := G_pos
160 have hk_pos : k_B > 0 := by unfold k_B; norm_num
161 have hpi_pos : Real.pi > 0 := Real.pi_pos
162 have hhbar_pos : hbar > 0 := hbar_pos
163 have h_denom_ne : 4 * G * bh.mass ≠ 0 := by positivity
164 have h_denom_ne' : 2 * Real.pi * k_B * c ≠ 0 := by positivity
165 have h_denom_ne'' : 8 * Real.pi * G * bh.mass * k_B ≠ 0 := by positivity
166 field_simp
167 ring
168
169/-! ## Thermodynamic Consistency -/
170
171/-- The first law of black hole mechanics: dM = T dS.
172
173 This connects mass, temperature, and entropy:
174 dM = (ℏ c³ / 8π G M k_B) × k_B × d(A/4l_P²)
175
176 Since A = 16π G² M² / c⁴, we get dA = 32π G² M dM / c⁴
177
178 This verifies dM = T dS! -/
179theorem first_law :
180 -- dM = T dS is satisfied