Sources

Matching entries: 206. Showing 201–206 of 206.

201. Paper · 2002

     Warp Drive With Zero Expansion

     1. José Natário(Author)

     José Natário revisits the common explanation that Alcubierre's warp drive works by contracting space ahead of the bubble and expanding it behind. He shows this contraction and expansion is only a side effect of Alcubierre's particular choice, and builds a similar warp drive with no contraction or expansion at all. Describing warp spacetimes by a vector field on flat 3-space, he shows they always violate some energy condition and that the volume expansion is the field's divergence. Choosing a divergence-free field gives a volume-preserving warp drive. Simple examples show horizons and infinite blueshifts, and he also discusses the global and optical properties of these spacetimes.

202. Paper · 2025

     Warp drives and Martel-Poisson charts

     1. Abhishek Chowdhury(Author)

     Abhishek Chowdhury extends the Alcubierre-Natário family of warp drives to an infinite class of spacetimes with similar properties. The construction uses Martel-Poisson charts, close relatives of the Painlevé-Gullstrand form, on Minkowski, anti-de Sitter and de Sitter backgrounds. Its key feature is a non-flat spatial metric that creates conical singularities at the origin in three dimensions and a nonzero Ricci scalar away from the origin in higher dimensions. Analysing how space expands and contracts and how these drives violate the null energy condition reveals scalings set by the global imprint of the conical defects. Light-cone tilting, event horizons and several generalisations are also worked out.

203. Paper · 2024

     Warp Factory: A Numerical Toolkit for the Analysis and Optimization of Warp Drive Geometries

     1. Christopher Helmerich(Author)
     2. Jared Fuchs(Author)
     3. Alexey Bobrick(Author)
     4. Brandon Melcher(Author)
     5. Luke Sellers(Author)
     6. Gianni Martire(Author)

     Helmerich and colleagues present Warp Factory, a MATLAB toolkit that computes stress-energy tensors from spacetime metrics using second- and fourth-order finite differences. Its analyzer samples null and timelike vectors because nonnegative energy density for one stationary observer does not establish the energy conditions. A genetic optimization example starts with an Alcubierre bubble of 20 metres radius moving at 0.5c and reduces the integrated null energy condition (NEC) violation measure to 2.1 × 10⁴⁴. The optimization retains fixed passenger and outer boundaries, limiting its ability to remove violations rooted in those boundaries. Their numerical reconstruction of a Lentz geometry also shows weak-condition violations; the authors separately identify smoothing-dependent negative-energy points, preserving the distinction between that reconstruction and the original analytic construction.

204. Report · 2011

     Warp Field Mechanics 101

     1. Harold White(Author)

     White begins with a review of the Alcubierre warp drive metric and describes how the phenomenon might work based on the original paper. The canonical form of the metric gave insight into the field potential and boost, and remedied a critical paradox in the original concept of operations. White notes that the metric violates the strong, weak and dominant energy conditions because of the need for negative energy density. A finding new to the literature is that the peak energy density requirement can be greatly reduced by allowing the wall thickness of the warp bubble to increase. He closes with an overview of a warp field interferometer test bed being implemented in a NASA advanced propulsion physics laboratory.

205. Paper · 2021

     Worldline numerics applied to custom Casimir geometry generates unanticipated intersection with Alcubierre warp metric

     1. Harold White(Author)
     2. Jerry Vera(Author)
     3. Arum Han(Author)
     4. Alexander R. Bruccoleri(Author)
     5. Jonathan MacArthur(Author)

     Harold White and colleagues, analysing for a DARPA-funded project how energy density may be structured inside a Casimir cavity under the dynamic vacuum model, report an unexpected link to warp metrics. Worldline numerics applied to this cavity gave results qualitatively similar to a two-dimensional picture of the energy density the Alcubierre warp metric requires. A toy model with a 1 µm sphere centred in a 4 µm cylinder gave a three-dimensional Casimir energy density that correlates well with those requirements. This points to chip-scale experiments that could look for tiny signatures of a real, if humble, warp bubble.

206. Paper · 2005

     Wormholes supported by a phantom energy

     1. Sergey Sushkov(Author)

     Sergey Sushkov takes phantom energy, usually treated as matter spread evenly through the universe with an equation-of-state parameter w below −1, and extends it to uneven, spherically symmetric spacetimes. The motivation is direct: wormholes need matter that violates the weak energy condition, and phantom energy is a natural candidate for that exotic matter. He shows that such a distribution of phantom energy can hold a static wormhole open. He finds an exact solution for such a wormhole and shows that the phantom energy sits mainly close to the wormhole's throat. The largest sphere around the throat that holds most of this energy depends on w and has a firm upper size limit.