From owner-freebsd-chat Tue May 25 10:31:39 1999 Delivered-To: freebsd-chat@freebsd.org Received: from tele-post-20.mail.demon.net (tele-post-20.mail.demon.net [194.217.242.20]) by hub.freebsd.org (Postfix) with ESMTP id ECAD314F35; Tue, 25 May 1999 10:30:46 -0700 (PDT) (envelope-from dmlb@ragnet.demon.co.uk) Received: from [158.152.46.40] (helo=ragnet.demon.co.uk) by tele-post-20.mail.demon.net with esmtp (Exim 2.12 #2) id 10mL2B-000IHD-0K; Tue, 25 May 1999 17:30:36 +0000 Received: from dmlb by ragnet.demon.co.uk with local (Exim 2.12 #1) id 10mBYQ-0006q0-00; Tue, 25 May 1999 08:23:14 +0100 Content-Length: 1288 Message-ID: X-Mailer: XFMail 1.3 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <19990524233433.D10261@futuresouth.com> Date: Tue, 25 May 1999 08:23:14 +0100 (BST) From: Duncan Barclay To: "Matthew D. Fuller" Subject: Re: secure deletion Cc: chat@FreeBSD.ORG, CONDOR , Eivind Eklund Sender: owner-freebsd-chat@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On 25-May-99 Matthew D. Fuller wrote: > On Fri, May 21, 1999 at 02:13:09PM +0200, a little birdie told me > that Eivind Eklund remarked >> >> You want to run them through a microwave oven first. This will break >> the recording material (not the plastic) into approx 1 inch long >> areas, using a neat pattern of lightning to do it (I'm not kidding). >> >> No prize but passing your physics class if you can say why it goes to >> approx an inch long pieces, and all the effects then stop. > > Wavelength of the (appropriately named) microwaves? > > Microwaves use radio waves at the fundamental frequency of water, no? Microwaves operate in the 2.4GHz ISM band, just like 802.11 wireless LAN. Water resonates at about 20GHz, but with a low enough Q that the 2.4GHz gets the molecules moving. One major reason for not operating at 20GHz is that meat/food is very reflective to 20GHz (I can lookup the complex permativity for you if you need it) so that microwaves don't get into the food. Duncan --- ________________________________________________________________________ Duncan Barclay | God smiles upon the little children, dmlb@ragnet.demon.co.uk | the alcoholics, and the permanently stoned. ________________________________________________________________________ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message