Dr. White,

Hello, David Woolsey here with a few questions about the tests of the (supposed) reactionless drive. But first, a "teaser": I spent 14 years working for Norman Seaton at the Laboratory for Science in Berkeley, California. We manufactured the most stable HeNe lasers ever made for commercial sale (see Sam's Laser FAQ page at http://repairfaq.cis.upenn.edu/Misc/laserhst.htm#hstlfs for some history). I might have access to a device or two that you might be interested in, so you might not want to simply "86" this email.

Now, for the questions/observations. They mostly concern the contents of the paper _Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum_ by D. Brady, H. White, P. March, J. Lawrence, and F. Davies. That paper is where I found the description of the test procedures used to characterize the thrust that the reactionless drive seems to be generating.

1. The paper shows that there was COMSOL modeling of the electromagnetic response of the test objects. However, the modeling seems to assume free-space conditions for the test object. Which leads to observations 2 and 3:

2. The tests were carried out within an enclosed, conductive chamber. Electromagnetic emissions within a conductive enclosure can set up some very strange behaviors because of the very high cavity Q of such enclosures. For example, I know of persons who have experimented with cell phones enclosed within metal pipes -- both ends sealed by screw on caps -- the cell phones can *still* communicate with the outside world. This happens because the EM radiation trapped within the enclosure "rings up" (I guess that would be a pun) to a very high intensity such that the rate of loss from the trapped fields balances with the rate of generation of the radiation within the enclosure. A significant portion of the losses are in fact radiation escaping from the non-perfect seals of the enclosure (because the end caps are not at the same (RF) potential as the pipe walls due to imperfect contact at the thread interface), while the rest are resistive losses of the walls of the pipe. The inclusion of an absorber within the enclosure to reduce its Q factor eliminates the RF coupling between the interior and exterior of the enclosure because the pattern of standing waves in the cavity can't "ring up". A piece of anti-static conductive foam inside the cavity would be sufficient to reduce the Q such that the RF coupling from inside to outside is suppressed.

3. If the fields inside the test enclosure are allowed to build up by a factor of the enclosure's Q, which is probably on the order of several thousand, then we can account for the observed forces produced by the test objects roughly as follows:

The force of light reflecting from a mirror is f = 2P/c where P is the incident optical power, c is the speed of light, and the factor of 2 comes from the fact the the light is reflected rather than absorbed. So a power of of 1 W gives a force of 6.7*10^-9 N or f = 6.7*10^-9 N/W

The test objects in the paper were experiencing a force of about 10^-6 N per Watt of input power, which is about 300 times higher than the expected "raw" thrust one would expect from just the recoil from the EM radiation emitted from the test objects (assuming it all went in one direction).

However, the environment that the test objects are in is an enclosed conductive cavity that will have a complicated structure of high intensity standing waves built up in it by any radiating Êsource placed within. And that does not seem to be accounted for in the experimental setup or in the simulations (if it were, there'd be some form of effective absorber incorporated into the enclosure in the paper).

I expect that the "thrust" effects that are being reported are a result of the intensified microwave radiation field within the cavity. If the cavity Q is on the order of several thousand then the resulting electromagnetic field intensity will be correspondingly higher than the few Watts being input into the device. The intense EM fields are acting very much like the fields in a macroscopic (microwave) optical tweezer -- pushing the test object around in the gradients of the cavity's standing wave pattern. Therefore, the resulting "thrust" would be an electromagnetic force acting between the object under test and the walls of the enclosure.

If there were to be included a few square feet of absorbing material on the interior walls of the test enclosure I'd bet that the thrust effects being reported would diminish by, oh, about 99%. If the thrust is still hundreds of times "too high" when the EM waves in the cavity have been sufficiently damped, then there might be something interesting going on. (Which I would **really** like to know about because it would point to answers for some very interesting questions unrelated to propulsion.)

Sorry to be really blunt, but if I understand what I've read, there was no modeling of the intensified electromagnetic fields that the test devices are *actually* embedded in when in the chamber. Furthermore, the test chamber appears to be almost exactly the reverse of what it should be -- it should be like a radar anechoic chamber, not a hall of mirrors. There can be correspondingly little confidence that what is being reported is anything but an unfortunate set of measurement artifacts. Or is my understanding incorrect about the test objects' environment and response?

Lastly, despite the blunt messaging here, I've decided to do the respectful thing and contact you directly about my observations, instead of simply putting them up on a blog somewhere (assuming they haven't already been posted by someone else -- I've been out of comms for two weeks and don't know what the blogospheric followup to your experiment has been). I hope you can give me credit for being at least a little tactful, I do think what you are doing -- speculative as it may be -- is worthwhile. I just want to see it done as right as can be.

Thanks for reading this far.

David Woolsey

P.S. Oh, yeah, what make/model of stabilized HeNe lasers are you using?