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Comment Re:If you believe in zero viscosity (Score 4, Interesting) 213

Perpetual motion is actually a fundamental property of the universe, though we usually call it inertia: a body will not stop moving, unless somebody moves it. Therefore, linear perpetual motion is the norm, with change of velocity depending on an outside force.
To make it even more interesting: non-linear perpetual motion is actually also present in all molecules, at any given temperature, even at 0 Kelvin. Quantum chemistry shows that vibrational motion in a molecule changes by energetic quanta, where at least half a quantum is always present in a vibrational degree of motion (so-called zero-point energy). Hence, the atoms in a molecule are always in motion, even at 0 K, and the motion is non-linear. In first approximation, especially for diatomic molecules, it can be described as an oscillation with a parabolic energy profile, for multi-dimentional molecules one usually gets ergodic movement that is a bit more complex to describe, and is usually considered chaotic where only the statistical properties are relevant.
But no free energy, of course.

Comment benchmarks (Score 4, Informative) 210

If I read the article correctly, it takes 348 seconds to transfer 1.9GB of data. That amounts to 5.6 MB/sec copyspeed, or about 11.2 MB/s transfer speed on the disk (read + write). A simple, $50 SATA-II disk is able to sustain 50MB/s transfers, read or write, and quality hard disks even more. What is happening with the remaining bandwidth? There is some seek overhead, directory updates, etc but nothing that would slow it down. Also, 11MB/s is hardly a big strain for main memory, cache or PCI bus bandwidth, so it should not affect responsiveness at all. Somebody mentioned lack of rigorous benchmarking because no variance was measured. In this case, it seems many times too slow compared to the physical limit of the disk, so something is fundamentally wrong, irrespective of variance.

I quickly tested this on a SuSE linux machine, and found copy speeds of about 19 MB/sec including syncing to disk (so not tainted by buffering), or 38.2 MB/sec total disk transfer. Accounting for seek overhead, directory updates, etc, that feels like it is limited by the hardware (about 50MB/s for sequential access on this computer). Vista seems to lose about a factor of 4 relative to the hardware. Given the speed of the machine used (cpu, memory, videocard etc) any gui-aspects should not be the limiting factor. All other factors such as different filesystem etc should likewise have a negligable influence. I guess I'll stick to linux for the moment for my IO-intensive work...

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