On the Infeasibility of Low-Energy Warp Drive via Metamaterial Gravitational Coupling
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866911065935183872 |
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| author | Rodal, José |
| author_facet | Rodal, José |
| contents | Recent ``low-energy'' warp-drive concepts propose replacing the constant gravitational coupling $κ_0$ with a spatially varying scalar field $κ(x)$ set by an engineered metamaterial's electromagnetic response. We show that the idea fails on both theoretical and experimental grounds. A prescribed, non-dynamical $κ(x)$ in the field equation $G^{μν} = κ(x)T^{μν}$ clashes with the contracted Bianchi identity, $\nabla_μG^{μν} \equiv 0$, forcing $\nabla_μT^{μν} \neq 0$ and thus violating local energy-momentum conservation. Making $κ(x)$ dynamical yields a scalar-tensor theory in which the scalar mediates a new long-range force that breaks the strong equivalence principle; Solar-System and pulsar-timing experiments already restrict $|γ- 1| \lesssim 10^{-5}$, excluding any technologically useful coupling. Junction-condition analysis further shows that any interface where $κ$ changes demands a $δ$-function layer of stress-energy, while even steep continuous profiles are ruled out by torsion-balance, lunar-laser, and spacecraft Doppler measurements. Hence the concept is untenable: a non-dynamical scheme violates conservation laws, and its scalar-tensor completion is falsified by existing data.. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_09724 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | On the Infeasibility of Low-Energy Warp Drive via Metamaterial Gravitational Coupling Rodal, José General Relativity and Quantum Cosmology High Energy Physics - Theory 83C05, 83C50, 83D05 (Primary) Recent ``low-energy'' warp-drive concepts propose replacing the constant gravitational coupling $κ_0$ with a spatially varying scalar field $κ(x)$ set by an engineered metamaterial's electromagnetic response. We show that the idea fails on both theoretical and experimental grounds. A prescribed, non-dynamical $κ(x)$ in the field equation $G^{μν} = κ(x)T^{μν}$ clashes with the contracted Bianchi identity, $\nabla_μG^{μν} \equiv 0$, forcing $\nabla_μT^{μν} \neq 0$ and thus violating local energy-momentum conservation. Making $κ(x)$ dynamical yields a scalar-tensor theory in which the scalar mediates a new long-range force that breaks the strong equivalence principle; Solar-System and pulsar-timing experiments already restrict $|γ- 1| \lesssim 10^{-5}$, excluding any technologically useful coupling. Junction-condition analysis further shows that any interface where $κ$ changes demands a $δ$-function layer of stress-energy, while even steep continuous profiles are ruled out by torsion-balance, lunar-laser, and spacecraft Doppler measurements. Hence the concept is untenable: a non-dynamical scheme violates conservation laws, and its scalar-tensor completion is falsified by existing data.. |
| title | On the Infeasibility of Low-Energy Warp Drive via Metamaterial Gravitational Coupling |
| topic | General Relativity and Quantum Cosmology High Energy Physics - Theory 83C05, 83C50, 83D05 (Primary) |
| url | https://arxiv.org/abs/2507.09724 |