Just in case you wanted to know how dept... Cheers, Bob --- begin forwarded text Date: Tue, 23 Jan 1996 11:21:54 -0500 (EST) From: Paul Picot <ppicot@irus.rri.uwo.ca> To: Philip Stein <pstein@measurement.com> Cc: jeff@rand.org, technomads@UCSD.EDU Subject: Re: FYA/I: Who'd have gaussed it? Mime-Version: 1.0 Zounds! A guantlet thrown! I accept!

...

It just occured to me: a good way to do this might be with The Mother Of All Degaussing Coils. [...] If you can degauss the Queen Mary, surely all the disk drives in a little office building should pose no problems, right?

This won't work (thank goodness). The local field strengths needed to change the magnetic state of a disk platter (whose coercivity is MUCH higher than that of the queen mary) is orders of magnitude greater than what can be generated at any distance.

Use a coil *around* the building. This makes the problem just within the realm of the possible, though horribly impractical. I'll spare the collected minds and spool spaces of the technomads list the details, and reduce this to a recipe: Collect the following: - 20 miles of 0000-guage insulated copper wire (about 32 tons worth) - five standard 20 MW gas-turbine power plant generators (about 20 tons ea.) - fuel for about 10 minutes of operation (about 4 tons) - five standard high voltage transmission rectifier modules for the above. - one standard 69,000 volt, 10,000 amp transmission-line contactor set Wrap 1000 turns of the wire around your target. This makes a bundle about 18 inches in diameter. Wire your generators and rectifiers to yield 70,000 volts DC, and connect them via the contactor to the coil. Fire up the turbines, and take them to redline, storing kinetic energy in the rotors. Firewall the turbines and trigger the contactor. It will take about 10 seconds for the coil current to hit 8000 amps, creating a 1-tesla magnetic field within the coil. This is sufficient to erase magnetic media. Then kill your generators before everything melts :-). And this is now certainly outside the scope of technomads... - Paul --- end forwarded text ----------------- Robert Hettinga (rah@shipwright.com) e$, 44 Farquhar Street, Boston, MA 02131 USA "Reality is not optional." --Thomas Sowell The NEW(!) e$ Home Page: http://thumper.vmeng.com/pub/rah/