How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
- AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.
These labels describe origin, not correctness: citations and verification chips remain separate evidence.
FALSE: a field with vanishing divergence has zero outward flux through the boundary of every solid it surrounds
Statement
False claim: if a vector field has vanishing divergence wherever it is defined, then its outward flux through the boundary of every solid it surrounds is zero.
The claim looks like the divergence-free corollary on the A page, but it quietly weakens the hypothesis. The proved corollary requires the field to be on an open set containing the whole solid, not merely away from a singularity inside it.
Facts & Assumptions
Given: The inverse-square field on .
The outward flux of this field through the sphere of radius centred at the origin is (The outward flux of the inverse-square field through a sphere centred at the origin is ).
The divergence of this field is zero at every point where it is defined (The inverse-square field is divergence free, and its flux through the sphere bounding the translated unit ball vanishes).
If a finite gluing of elementary solid regions is given and a field on an open set containing its union has vanishing divergence, then its outward boundary flux is zero (A field with vanishing divergence has zero outward flux through the boundary of a glued elementary solid).
The divergence of a field on an open subset of is the sum of its coordinate partial derivatives (Divergence and curl of a vector field).
Flux is computed against the oriented area vector of a patch (Unit normal fields, orientations, and flux through a regular surface patch).
For a finite patch presentation, total flux is the sum of the patch fluxes (Finitely patched regular surfaces, their area, scalar integrals, and flux).
Refutation
By [L2] and [F1], the witness field has vanishing divergence at every point where it is defined.
By [L1], its outward flux through any sphere centred at the origin is , so in particular it is not zero.
Steps 1.1 and 1.2 contradict the claim, so the claim is false.
What fails is not the divergence theorem or the corollary [L3], but the weakened hypothesis: the field is not on any open set containing the solid bounded by a sphere centred at the origin.
The same field on a sphere whose enclosed ball misses the origin does satisfy the corollary and has zero flux there, exactly as The inverse-square field is divergence free, and its flux through the sphere bounding the translated unit ball vanishes records.
Remarks
- The example separates two different statements that are often conflated: vanishing divergence on the punctured domain, and the existence of an open neighbourhood of the solid on which the field is .
Depends on
- The outward flux of the inverse-square field through a sphere centred at the origin is $4\pi$
- The inverse-square field is divergence free, and its flux through the sphere bounding the translated unit ball vanishes
- A field with vanishing divergence has zero outward flux through the boundary of a glued elementary solid
- Divergence and curl of a $C^1$ vector field
- Unit normal fields, orientations, and flux through a regular surface patch
- Finitely patched regular surfaces, their area, scalar integrals, and flux
Used by
Nothing in the library uses this result yet.
Dependency tree · two levels
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Sources
- J. Feldman, A. Rechnitzer and E. Yeager, CLP-4 Vector Calculus, Warning 4.3.3 (standard reference, not scraped)
- G. Strang and E. Herman, Calculus Volume 3, Theorem 6.21 (standard reference, not scraped)