Volume 2 Issue 8, August 2006

Volume 2 Issue 8

In systems ranging from our unpredictable weather to flame acceleration of a supernova, the Rayleigh-Taylor instability is the underlying mechanism; liquids of different densities mix in such a way as to lower the energy of the system. For a fluid, the Reynolds number is a measure of whether the flow is laminar or turbulent, with turbulence – and eddies of varying scales – setting in above 2,300 or so. These eddies will affect flame propagation in type Ia supernovae, the 'standard candles' used to estimate the expansion rate of the Universe. As it is not possible to measure the dynamics of turbulent combustion in a supernova, William Cabot and Andrew Cook use the largest-to-date direct numerical simulation to study the self-similarity, scaling and growth rate of thermonuclear flames.

Article by Cabot et al | News and Views by Schmidt

Editorial

Commentary

  • Commentary |

    Using observations to infer the values of some parameters corresponds to solving an 'inverse problem'. Practitioners usually seek the 'best solution' implied by the data, but observations should only be used to falsify possible solutions, not to deduce any particular solution.

    • Albert Tarantola

Thesis

Books and Arts

  • Books & Arts |

    One generation passeth away, and another generation cometh: but the Earth abideth for ever. The Sun also ariseth, and the Sun goeth down, and hasteth to his place where he arose. (Ecclesiastes 1:4–5)

    • Richard Webb

Research Highlights

News and Views

  • News & Views |

    Electromagnetic waves below the plasma frequency usually reflect off a metal. A theory now suggests that a nonlinear Josephson plasma wave — an excitation in an anisotropic superconductor — can propagate below the plasma frequency.

    • Joe Orenstein
  • News & Views |

    Turbulent flows, such as those generating the thermonuclear flames of a supernova, are difficult to measure, so we rely on simulations for insights. The largest simulation to date reveals unexpected flow dynamics.

    • Wolfram Schmidt
  • News & Views |

    Many predictions and consequences of quantum mechanics defy intuition. New insights into the limits of communication between spatially separated parties could bring us closer to grasping the nature of the quantum world.

    • Sandu Popescu
  • News & Views |

    Further analysis of controversial data questioning the role of surface plasmons in extraordinary optical transmission reasserts the conventional view, and suggests there is still much to be done to understand the details of this phenomenon.

    • Taco D. Visser
  • News & Views |

    How did the first stars form, and the early Universe develop? A meeting of minds from astronomy, cosmology and nuclear physics achieved some consensus on what we know, and what we don't.

    • Timothy C. Beers
    •  & Jason Tumlinson
  • News & Views |

    One might have expected there was little left to learn about the dynamics of hot charge-carriers in semiconductors. But an unexpected heating mechanism in semiconducting quantum rods suggests there is still room for surprise.

    • Todd D. Krauss

Letters

Articles

Endgame

Errata