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v473_entropic_action_bridge.py
verification/v473_entropic_action_bridge.py
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"""v473 -- GRAV.ENTROPIC.ACTION.01: the entropic-action bridge -- Bianconi's
"Gravity from entropy" (Phys. Rev. D 111, 066001 (2025); arXiv:2408.14391) as an
EXTERNAL CANDIDATE for the local volume action behind TFPT's already-closed,
parameter-free Einstein equation (v358/v359). This module quantifies the bridge;
it does NOT adopt the external action as TFPT structure and closes NO gate.
TFPT's field equation G_ab + Lambda g_ab = (1/c3) T_ab is derived thermodynamically
(entanglement equilibrium, v359) -- honestly typed "equation of state, not a
from-action quantisation" [O]. Bianconi's entropic action S_B = -Tr_F ln(G~ g~^-1)
(the quantum relative entropy between the spacetime metric and the matter-induced
metric, Araki-related via Delta^{1/2}_{G~,g} = G~ g~^-1, her Appendix C) is a local
covariant action whose variation yields modified Einstein equations that reduce to
Einstein + emergent nonnegative Lambda at low coupling -- exactly the missing
variational layer, IF the bridge identities hold. What is checkable today:
[E] 1. CARRIER HODGE COUNT. Bianconi's matter fiber is Omega^{0,1,2}; on the
five-slot carrier C^5 (NOT on 4d spacetime, where the fiber is 1+4+6=11)
the count is 1+5+10 = 16 = 2^(g_car-1) = dim S+_{D5}, and the Hodge star
L^1 ~= L^4 folds it onto the even exterior algebra L^even C^5 -- the
carrier half-spinor's own Pascal row (v2/v44). Vector-space identity
ONLY; Clifford/Dirac/leaf/Calderon compatibility stays open (check 7).
[E] 2. COEFFICIENT MATCH (the one quantitative pin). Bianconi's weak-coupling
Lagrangian is L = 3 beta R - alpha L_matter + ... (her Eq. (45); the 3 =
the three form blocks 0,1,2). Matching 3 beta'/l_P^2 (l_P^2 = G) to the
TFPT EH normalisation 1/(16 pi G) = c3/(2G) fixes her free constant
EXACTLY: beta'_B = c3/6 = 1/(48 pi). Structural echo: the 6 = 3 blocks x
2 (EH 1/2) = p2 = |R+(A3)| -- recorded as consistency, NOT a new proof.
[E] 3. ENTROPY POTENTIAL = QUADRATIC LAMBDA. Her emergent constant is
Lambda_G = (1/2 beta) Tr_F(G - I - ln G) with s(x) = x - 1 - ln x >= 0,
s(1) = 0, s''(1) = 1 (exact series) => Lambda_G = (1/4 beta) Tr eps^2 +
O(eps^3): Lambda >= 0 and QUADRATIC around the entropic fixed point.
[E] 4. THE LAMBDA CHANNEL CLOSES ALGEBRAICALLY. With the TFPT displacement
eps_* = e^{-1/alpha} Q the quadratic entropy gives Lambda ~ e^{-2/alpha},
the SAME suppression as the closed TFPT branch rho_Lambda/Mbar^4 =
(3/4 pi^2) e^{-2/alpha} (v60); matching prefactors with beta' = c3/6 and
l_P^2 Mbar^2 = c3 yields the EXACT normalisation target
Tr_F Q^2 = 32 c3^4 = 1/(128 pi^4) = (2/3) delta_top -- a closed algebraic
target for the two-form block (binom(5,2) = 10 = the pair sector), [C]
until an explicit Q is constructed.
[E] 5. LOG = ALL-SCALE HEAT KERNEL (Frullani). -ln A = int_0^inf dt/t
(e^{-tA} - e^{-t}) -- her log action is an all-scale-integrated heat-kernel
action, the correct genre to compare with TFPT's relative spectral action
S_rel,chi (KMS cutoff); verified numerically to 1e-12.
[E] 6. R^2 KILL TEST QUANTIFIED (the honest wall). The raw log expansion
-Tr ln(I+X) = -Tr X + (1/2) Tr X^2 - ... carries a curvature-squared
coefficient of order (beta')^2 = (c3/6)^2; TFPT's Starobinsky sector needs
Mbar^2/(12 M_scal^2) = 1/(12 c3^7) (M_scal^2 = c3^7 Mbar^2, v36). The
EXACT mismatch is 1/(12 c3^7) / (c3/6)^2 = 3 c3^{-9} = 3 (8 pi)^9
~ 1.20e13 -- THIRTEEN orders of magnitude. A direct identification of the
raw entropic action with the TFPT R^2 sector is therefore FALSE without a
mechanism (scalaron = light trace mode of the G-field generating c3^{-9},
or KMS-spectral renormalisation) -- the pre-registered kill test.
[C] 7. THE COMPRESSION CONJECTURE (recorded, not proven). The bridge proper is
P_Sigma (G~ g~^-1) P_Sigma = Delta_Sigma^{1/2} -- the physical Calderon
compression of her relative metric operator equals the TFPT seam modular
operator; if proven, S_B is a local volume representation of the TFPT
relative spectral action. Open with the operator-level Hodge items
(Clifford action, Dirac intertwining, leaf involution, Calderon
polarisation). Lorentzian positivity of G~ g~^-1 is NOT automatic
(timelike gradients); TFPT's OS/reflection-positive route is the sturdier
construction -- recorded.
[O] 8. NOT CLOSED. The equation-of-state status of v359 stays [O]; adopting
S_B would close it ONLY after (7) and the R^2 mechanism (6). No status
marker moves; external reference, zero TFPT knobs added.
NET TYPING: [E] the five exact identities + the quantified gap; [C] the
compression conjecture, the eps_* assignment and the Q-target; [O] the
variational-completion gate itself. External anchor: G. Bianconi, "Gravity from
entropy", Phys. Rev. D 111, 066001 (2025), arXiv:2408.14391 (DOI
10.1103/PhysRevD.111.066001). Mixed exact (sympy, Wolfram-mirrored) + one
numerical quadrature (mpmath).
"""
import mpmath as mp
import sympy as sp
from tfpt_constants import check, summary, reset, g_car, N_fam
pi = sp.pi
c3 = sp.Rational(1, 8) / pi
def run():
reset()
print("v473 GRAV.ENTROPIC.ACTION.01: the Bianconi entropic-action bridge (PRD 111, 066001 (2025))")
# 1. carrier Hodge count: Omega^{<=2}(C^5) has dim 1+5+10 = 16 = dim S+_{D5}
dims = [sp.binomial(g_car, k) for k in (0, 1, 2)]
dim_splus = 2 ** (g_car - 1)
even = [sp.binomial(g_car, k) for k in (0, 2, 4)]
fiber_4d = sum(sp.binomial(4, k) for k in (0, 1, 2))
check("CARRIER HODGE COUNT [E]: dim Omega^{0,1,2}(C^5) = %s = 16 = 2^(g_car-1) = "
"dim S+_{D5}; Hodge star L^1 ~= L^4 folds onto L^even C^5 (dims %s); "
"two-form block binom(5,2) = 10; on 4d spacetime the fiber is only "
"1+4+6 = %d -- the 16 REQUIRES the five-slot carrier (vector-space "
"identity only)" % ("+".join(str(d) for d in dims), even, fiber_4d),
sum(dims) == dim_splus == sum(even) == 16 and dims[2] == 10 and fiber_4d == 11)
# 2. coefficient match: 3 beta' / G = 1/(16 pi G) => beta' = c3/6 = 1/(48 pi)
beta_p = sp.solve(sp.Eq(3 * sp.Symbol('bp'), sp.Rational(1, 16) / pi), sp.Symbol('bp'))[0]
p2_A3 = sp.binomial(4, 2) # |R+(A3)| = 4*3/2 = 6 positive roots
check("COEFFICIENT MATCH [E]: 3 beta'_B = 1/(16 pi) = c3/2 => beta'_B = %s = "
"c3/6 = 1/(48 pi); the 6 = 3 form blocks x 2 (EH 1/2) = p2 = |R+(A3)| = %d "
"(structural echo, not a proof)" % (beta_p, p2_A3),
sp.simplify(beta_p - c3 / 6) == 0 and
sp.simplify(beta_p - sp.Rational(1, 48) / pi) == 0 and p2_A3 == 6)
# 3. entropy potential s(x) = x - 1 - ln x: nonnegative, quadratic minimum at x=1
x, eps = sp.symbols('x eps', positive=True)
s = x - 1 - sp.log(x)
series = sp.series(s.subs(x, 1 + eps), eps, 0, 4).removeO()
smin = sp.solve(sp.diff(s, x), x)
check("ENTROPY POTENTIAL [E]: s(x) = x - 1 - ln x has unique stationary point "
"x = %s with s = 0, s'' = 1, series s(1+eps) = %s => Lambda_G = "
"(1/4 beta) Tr eps^2 + O(eps^3) >= 0, QUADRATIC around the fixed point"
% (smin, series),
smin == [1] and s.subs(x, 1) == 0 and sp.diff(s, x, 2).subs(x, 1) == 1 and
sp.simplify(series - (eps ** 2 / 2 - eps ** 3 / 3)) == 0)
# 4. Lambda channel: (1/4 beta) e^{-2/a} TrQ^2 = (3/4 pi^2) e^{-2/a} Mbar^2
# with beta = beta' l_P^2, l_P^2 Mbar^2 = G Mbar^2 = 1/(8 pi) = c3
TrQ2 = sp.Symbol('TrQ2')
sol = sp.solve(sp.Eq(TrQ2 / (4 * (c3 / 6) * c3), sp.Rational(3, 4) / pi ** 2), TrQ2)[0]
delta_top = 48 * c3 ** 4
check("LAMBDA CHANNEL [E->C]: eps_* = e^{-1/alpha} Q makes Lambda_G ~ e^{-2/alpha} "
"= the closed v60 branch (3/4 pi^2) e^{-2/alpha}; prefactor match "
"(beta' = c3/6, l_P^2 Mbar^2 = c3) => Tr_F Q^2 = %s = 32 c3^4 = "
"1/(128 pi^4) = (2/3) delta_top -- exact algebraic target for the "
"two-form (pair) block, Q itself unconstructed [C]" % sol,
sp.simplify(sol - 32 * c3 ** 4) == 0 and
sp.simplify(sol - sp.Rational(1, 128) / pi ** 4) == 0 and
sp.simplify(sol - sp.Rational(2, 3) * delta_top) == 0)
# 5. Frullani: -ln a = int_0^inf dt/t (e^{-t a} - e^{-t}) (all-scale heat kernel)
mp.mp.dps = 30
frul = lambda a: mp.quad(lambda t: (mp.e ** (-t * a) - mp.e ** (-t)) / t, [0, mp.inf])
err = max(abs(frul(a) + mp.log(a)) for a in (mp.mpf('0.4'), mp.mpf('2.5')))
check("LOG = ALL-SCALE HEAT KERNEL [E] (Frullani): -ln A = int dt/t (e^{-tA} - "
"e^{-t}), max residual %.1e -- the entropic action is an all-scale "
"heat-kernel action, the right genre against S_rel,chi (KMS cutoff)" % err,
err < mp.mpf('1e-12'))
# 6. R^2 kill test: raw (c3/6)^2 vs TFPT 1/(12 c3^7); exact gap 3 c3^-9 = 3 (8 pi)^9
raw = (c3 / 6) ** 2
staro = 1 / (12 * c3 ** 7)
gap = sp.simplify(staro / raw)
check("R^2 KILL TEST [E/X-guard]: raw log-expansion coefficient (c3/6)^2 vs "
"TFPT Starobinsky Mbar^2/(12 M_scal^2) = 1/(12 c3^7) (M_scal^2 = c3^7 "
"Mbar^2, v36) -- EXACT gap %s = 3 (8 pi)^9 ~ %.3e (13 orders): a direct "
"identification of the raw entropic action with the TFPT R^2 sector is "
"FALSE without a mechanism (light G-trace mode generating c3^{-9}, or "
"KMS-spectral renormalisation)" % (gap, float(gap)),
sp.simplify(gap - 3 * (8 * pi) ** 9) == 0 and
abs(float(gap) - 1.2002728758784e13) / 1.2e13 < 1e-3)
# 7. the compression conjecture (recorded)
check("COMPRESSION CONJECTURE [C] (recorded, NOT proven): P_Sigma (G~ g~^-1) "
"P_Sigma = Delta_Sigma^{1/2} -- the Calderon compression of the relative "
"metric operator = the TFPT seam modular operator; plus the operator-level "
"Hodge items (Clifford, Dirac, leaf involution, Calderon polarisation); "
"Lorentzian positivity NOT automatic -- TFPT's OS route is the sturdier "
"construction", True)
# 8. nothing closes
check("NOT CLOSED [O]: v359's equation-of-state status stays [O]; adopting S_B "
"would close it only after (7) + the R^2 mechanism (6); no marker moves, "
"zero TFPT knobs added (external anchor: Bianconi, PRD 111, 066001 (2025), "
"arXiv:2408.14391)", True)
return summary("v473 GRAV.ENTROPIC.ACTION.01: Bianconi entropic-action bridge -- [E] "
"1+5+10=16=dim S+ (carrier-only; 4d fiber is 11), beta'_B = c3/6 = 1/(48 pi) "
"pinned, Lambda_G quadratic-nonnegative with exact target Tr Q^2 = 32 c3^4, "
"Frullani all-scale heat kernel, R^2 gap EXACTLY 3 (8 pi)^9 ~ 1.2e13; [C] "
"compression conjecture P (G g^-1) P = Delta^1/2; [O] variational completion "
"open, no gate closed")
if __name__ == "__main__":
raise SystemExit(1 if run() else 0)
Recorded source fingerprint
78b4a255254092b030d8cd40ddc1008f08c1f4997b23e818fcd33ca2aedc7ed0
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