The Spacetime Metric

Profile

Miguel Alcubierre

theoretical physicist and numerical relativist, Instituto de Ciencias Nucleares, UNAM

Alcubierre studies gravity with computer calculations of Einstein’s equations, including black holes and gravitational waves. In 1994 he proposed a spacetime geometry in which space expands behind a moving region and contracts ahead of it, allowing faster-than-light travel relative to distant observers in the mathematical model. His paper also identifies the need for exotic matter to produce that geometry. The calculation connects a chosen shape of spacetime to its required matter and energy.

Affiliations

  • Universidad Nacional Autónoma de México (UNAM), Instituto de Ciencias Nucleares

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Bibliography

A bibliography listing does not establish authorship. Credits appear under attribution.

Published bibliography entries: 2. Showing 1–2 of 2.

  1. Listed work

    Paper · 1994

    The warp drive: hyper-fast travel within general relativity

    1. Miguel Alcubierre(Author)

    Alcubierre’s 1994 paper specifies a mathematical geometry in which space expands behind a moving region and contracts ahead of it. A spacecraft at its center follows a freely falling path, remaining below the local speed of light even when distant observers assign it faster-than-light motion. In the prescribed geometry, its clock runs at the same rate as distant clocks during this central trajectory. Tidal forces near the spacecraft can be small for suitable size and shape parameters, while forces near the boundary can be large. Calculating the required matter and energy reveals negative energy density and violations of classical energy conditions. The paper invokes quantum examples such as the Casimir effect but supplies no method for producing the required distribution.

  2. Listed work

    Paper · 2017

    Warp drive basics

    1. Miguel Alcubierre(Author)
    2. Francisco S. N. Lobo(Author)

    In this 2017 chapter, Alcubierre and Lobo examine warp geometries as mathematical ways to shorten distant journeys without the ship outrunning light in its immediate surroundings. For the Alcubierre geometry, they calculate negative energy density in the bubble walls, even at low speeds. Their analysis with a finite-mass ship relates the energy requirement to bubble speed, size and wall thickness. At faster-than-light bubble speeds, onboard signals cannot reach the outer front edge, so the crew cannot simply create or control the entire bubble on demand. They discuss Krasnikov’s alternative: modify the route during an initial outward journey to enable a shortened round trip. Suitably combined routes can form paths returning to an earlier time, although the original single Alcubierre geometry does not itself contain such loops.