Profile
Matt Visser
professor of mathematics, Victoria University of Wellington
Visser investigates traversable wormholes and the matter and energy required by proposed spacetime geometries. With Francisco Lobo, he calculates that the Alcubierre and Natário warp models violate classical energy conditions even at low speeds; these conditions constrain energy density and pressure. With Carlos Barceló and Stefano Liberati, he develops the study of analogue gravity, using other physical systems to model aspects of gravitational fields. These analogues offer ways to investigate related physics without equating the model system with an engineered spacetime.
Affiliations
- Victoria University of Wellington, New Zealand
Channels
Bibliography
A bibliography listing does not establish authorship. Credits appear under attribution.
Published bibliography entries: 2. Showing 1–2 of 2.
Listed work
Paper · 2011
Analogue Gravity
- Carlos Barceló(Author)
- Stefano Liberati(Author)
- Matt Visser(Author)
In this 2011 review, Barceló, Liberati and Visser explain how waves in materials can follow equations resembling those for fields in curved spacetime. A sufficiently fast fluid flow can prevent sound from travelling upstream, creating an acoustic counterpart of a black-hole horizon. The review compares water waves, ultracold atomic condensates and optical systems, examining where each analogy applies. It reports classical stimulated Hawking emission in water-wave experiments and a sonic horizon in a condensate kept stable for about eight milliseconds. At that time, reproducible detection of spontaneous quantum Hawking radiation remained an experimental target. The authors distinguish this effective geometry for waves from the equations governing gravity itself: reproducing curved-spacetime propagation does not automatically reproduce Einstein’s gravitational dynamics.
Listed work
Paper · 2004
Fundamental limitations on 'warp drive' spacetimes
- Francisco S N Lobo(Author)
- Matt Visser(Author)
Francisco Lobo and Matt Visser use warp drive spacetimes as thought experiments that probe the foundations of general relativity. They formulate the Alcubierre and Natário spacetimes carefully, make the notion of superluminal communication precise and confirm that both violate the classical energy conditions non-perturbatively. They apply linearised gravity to weak-field Alcubierre and Natário drives and test the energy conditions to first and second order in bubble velocity. They highlight a feature not remarked on before: a warp drive would be a reactionless drive. For both drives, significant energy condition violations persist even at arbitrarily low speeds. Treating the ship as a finite mass, the net negative energy in the warp field must be a significant fraction of the ship's mass.