Non-Lethal Weapons, Part I: Ray Gun or Ray Howitzer?

First, some housekeeping items. When I began this blog nearly a year ago, I hid behind a screen of anonymity because I was afraid of negative repercussions that might arise from incautious words I might write. Recently, eminent engineering ethics expert Steve Unger at Columbia University wrote me that he is thinking of starting a blog, and wanted to know why I didn't put my real name on mine. (He knows who I am because my emails all have a tag line with the blog's URL in it.) I thought about it and couldn't give him a good reason, so as of today my profile and the header show my real name. As always, comments are welcome. If you have sent me a comment and I haven't replied to you, it's because the blog machinery doesn't inform me of your email address. If you would like me to be able to contact you, send an email to kdstephan@txstate.edu at the same time you add a comment to this blog, and I'll be able to respond.

Now for the first-ever two-part series in this blog: non-lethal weapons. I thank George Michael Sherry of Fort Worth, Texas for bringing my attention to an Associated Press article that was carried on MSNBC on Jan. 25, 2007. According to this report, the ray gun of science-fiction legend has arrived. It takes the form of a truck that carries a kind of radar-antenna thing about fifteen feet high. Even if you're as far away as five hundred yards, the thing's beam can make you feel like you're on fire. No actual fire results, because the total amount of power involved is limited. A video clip shows a civilian—possibly a reporter—standing in a field at Moody Air Force Base outside Valdosta, Georgia. All of a sudden he jumps like a snake bit him, and starts to laugh, aware of how foolish he looks.

As a microwave engineer, I viewed these proceedings with decidedly mixed emotions. On the one hand, my pure-engineer side rejoiced to see some familiar old technology being used in a novel and possibly helpful way. The energy used—94-GHz millimeter waves—is something I have known about and done research with for years, although at a lower power level than what the military is using in the alleged ray gun. They have taken a high-power source—probably a vacuum tube of some kind—and focused the energy in a narrow beam that probably covers a few dozen yards' worth of people at a distance of 500 yards. Full disclosure requires me to say that about twenty years ago, I received some research funds from Raytheon Corporation, which built the unit used in these tests. The technology to do this has been around for years, if not decades, but perhaps the will to try this or the funding was lacking until now.

Before we get to the ethical issues, my pure-engineer side has some questions, though. I thought a ray gun was supposed to fit in your pocket. A more apt term for this thing is "ray howitzer," a howitzer being a piece of field artillery larger than a single man can conveniently carry. Not only does this gizmo require a large truck to haul it around (and probably a multi-kilowatt generator buzzing away somewhere), but because of fundamental physical laws, there is very little chance that they'll ever be able to make it much smaller than it is now. If they tried, the beam would spread out to where you'd be as likely to shoot yourself as anybody else nearby. And then there's the cost. The article didn't mention how many tax dollars the project used up, but unless vacuum-tube millimeter-wave technology has had some dramatic breakthroughs lately (and I haven't heard of any), you can bet that even in production-quantity runs this ray gun would set you back many hundreds of thousands a piece, if not more. And while a spokesperson for the military refused to comment on whether the rays would penetrate glass, I can say that without fear of contradiction, it depends. What I can say for sure is that even a thin sheet of metal such as aluminum foil will block the rays completely. While you might look silly walking around in an aluminum suit, you'd have no worries about being zapped by the millimeter-wave ray howitzer.

Now for the ethical questions. The issue of whether non-lethal weapons should be used at all is an interesting one, but there is not space here to give it justice. My main question in this area is, does the use of this device truly have no long-term health effects? Over the years there have been several studies that link exposure to high-power microwaves with the growth of cataracts in the eye. The prevalence of convenient and effective cataract surgery these days doesn't mean that we should quit worrying about giving people cataracts. It's a legitimate question whether exposure to just one "zap" from the ray howitzer could cause enough eye damage to lead to cataracts. That is a technical question for the appropriate experts, but I raise it here simply because it may not have been asked yet.

All things considered, I don't believe we have a lot to fear from people with ray guns roaming the streets and towns of America. I will be surprised if Raytheon or anybody else can make this technology cheaply enough for it to pose a threat to water cannons, tear gas, or other popular means of dispersing angry crowds. If my experience as a lecturer on microwave engineering is any guide, you could inspire a set of rioters with the same intense longing to be somewhere else that the ray howitzer inspires, by trying to teach them the Fourier transform that relates the size of the machine's dish to the size of the beam. And the lecturer would come a lot cheaper.

Sources: The ray gun article appeared on the MSNBC website at http://www.msnbc.msn.com/id/16794717/wid/11915829?GT1=8921. Information on the relation between cataracts and microwaves can be found at places such as the Communications Workers of America website (http://www.cwa-union.org/issues/osh/articles/page.jsp?itemID=27339127) and an index of research by professor of history Nicholas Steneck on the hazards of microwave radiation (http://myweb.cableone.net/mtilton/steneck.html). It appears that "normal" exposure to microwaves and radio-frequency radiation has few if any reproducible clinical effects, although many experts disagree on the conclusions that should be drawn from the abundance of research.