the physics arXiv blog

Month: January 2008

  • The mysterious volume of a black hole

      Work out the surface area of a non-spinning black hole and you’ll get the answer:     16π(Gm/c^2) /c^2   But ask what volume this surface contains and you’re in for a surprise. Turns out that the volume depends on how the 3-space within the black hole is defined. Now Brandon DiNunno and Richard…

  • In case ya missed ’em…

    …this week’s posts Cooling with sound Four letter wordistics Listening out for neutrinos Mapping the radioactive heat beneath our feet The shower temperature problem Oranges ‘n’ lemons

  • Oranges ‘n’ lemons

    The best of the rest from the physics arXiv: Gravitational Wave Detection with Atom Interferometry Quantum Entanglement in the Voltage Dependent Sodium Channel can Reproduce the Salient Features of Neuronal Action Potential Initiation The Evolution of the Earth-Moon System Based on the Dark Matter Field Fluid Model Constructing Bio-molecular Databases on a DNA-based Computer Exploring…

  • The shower temperature problem

    Here’s an interesting problem. Imagine a large hotel in which many people are taking a shower at the same time. There isn’t enough hot water to give everyone the shower temperature they’d like and a change in temperature in one shower effects everyone else’s. What strategy should individuals use to achieve the same temperature for…

  • Mapping the radioactive heat beneath our feet

    Geochemical bods tell us that the Earth is heated from within by the decay of various isotopes, mainly uranium, thorium and potassium. Knowing the distribution of these elements is crucial for understanding the Earth’s inner dynamics. Geochemists have penty of ideas about how the Earth’s interior may work but no way of taking measurements to…

  • Listening out for neutrinos

    A lotta neutrino detectors work by looking for the flares ‘n’ flashes of light generated on the rare occasion a neutrino smashes into something solid, like an atom.  Ya need to do a lotta lookin’ though, which is why neutrino detectors sit in vast pools of water or are dropped into the oceans or buried…

  • Four letter wordistics

    Ah know many of ya have a penchant for four letter words judging by the comments ya leave, so this post will be of interest. There are a possible (26)^4 = 456,976 possible four letter words although we English speakers have only got round to using a tiny fraction of ’em. It’s fairly easy to…

  • Cooling with sound

    The next generation of chips are gonna need some major coolin’, perhaps as much as 1000 Watts of cold per square centimetre. We’re talkin’ high-speed microprocessors, optoelectronics, micro- and millimeter-wave power electronics and power conditioning transistors for electronic motor control in hybrid vehicles power converters etc. These are machines that will generate significant heat. Ordinary coolin fans ain’t…

  • In case ya missed ’em

    This week’s posts on the physics arxiv blog: How to spot a wormhole The puzzle of flyby anomolies The Turing alternatives Information and evolution The bar at the heart of the galaxy

  • Clouds ‘n’ cottonwool

    The best of the rest from the physics arXiv: How Winding is the Coast of Britain ? Conformal Invariance of Rocky Shorelines Models for the Formation of Massive Stars Why are there so few hot Jupiters? Diamond Solitaire Phase transition in the fine structure constant