> from Michael on Tuesday 21 April 2009 08:07: > >Then ask yourself when you last had a water outage.
On Tue, Apr 21, 2009 at 10:02:23AM -0700, Eric Wilhelm wrote: > I think the typical cause of that is a gravity outage. > > The light in the fiber is more like water than electrons in copper... > But we should probably have some training if the water department is > going to run the internet. Agree to the last. However, we do not get our water backhauled from POPs in Seattle and Oakand. Nor does a pipe splice leak 10% of the water through 100nm gaps. Boring physics stuff: Electrons are very much like water molecules, actually, while light is not much like water at all. If you look at them statistically, 49% of electrons and water molecules are going upstream due to thermal vibration. Look at a waterfall, and realize that almost half the time every molecule is moving upstream (very briefly!). The thermal energy in the direction of motion is 1/2kT, or 13 milli-electron-volts, or 2.1e-21 joules, which can push a water molecule (3e-26kg) to an average thermal speed of 370 meters per second, a lot faster than the macroscopic average water flow can move. An electron (9e-31kg) moves thermally at 70 km/sec. The flow rate through a high current copper wire is 4A/mm2, which results in an average drift speed of 0.3mm/sec. It is the disturbances in the electric field that travel fast in wires. Light, on the other hand, travels one direction, thousands of kilometers through optical fiber with hardly any thermalization along the way. A photon is a boson, which means it prefers to travel in packs. While some city employees are bozos, and some vote in PACs, that does not give them any special talents with bosons. So light travels more like a school of herring, which penguins like to eat. Thus, this post is vaguely relevant to Linux. However, herring in water pipes, or optical fibers, or on your hard drive, are very bad. I would rather have bugs. Keith -- Keith Lofstrom [email protected] Voice (503)-520-1993 KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon" Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
