I understand that this is an old thread, but since a Google search brought it up, I thought I would add my 10 cents.
I'm a physicist who has been studying, researching, and experimenting with the dowsing effect for 5 years. I have been dowsing for 20 years. There's not nearly so much lost information as there is false information, people just have forgotten how to look for it.
A short list of valuable books on the topic:
- The D-Force by V. C. Reddish
- The Field of Rotating Masses by V. C. Reddish
- Principles and Practices of Radiesthesia by Alexis Mermet
- Le Pendule by Alexis Mermet
- The Torsind by Alexander Pugach
- Solar Energy and Dowsing in the Isles of Scilly by A. P. Tabraham
- On the Remote Influence of Stars on a Resistor by M. M. Lavrentiev
There's alot more out there to be read, but this should give you a solid, scientific, and very reliable foundation on the science behind how and why dowsing works, as well as some of what does NOT work and what does not affect it. A brief overview would be as follows:
Dowsing is not magic, nor is it spiritual in any way. It will not help you find answers to questions, or point you toward what you want.
Any rotating mass will generate a torsion field in space as was initially proposed in the Einstein-Cartan theory, though the field is different in structure and strength than they initially supposed.
Because the sun and Earth are both rotating, we, standing on the earth, have the Earth's signal passing through our bodies and being interacted with by the sun's. This causes the electrical resistance of our nerves to change, which in turn causes our arms to move without our awareness, and those movements are exaggerated by the instrument we use. The pendulum, Y-stick, or L-rods are all just an indicator of our bodies' motions, and are not performing any real interactive function themselves. For this reason it is just as effective (outside of an individual's own beliefs hindering them) to use a plastic pendulum as it is to use one made from monocrystalline quartz. Electrical conductivity of the instrument makes no difference whatsoever. Furthermore, electrical signals, fields, etc and magnetic fields do not affect a dowser's ability to dowse.
Any parallel objects will act the same on the torsion field as the double-slit experiment will, causing diffractive patterns. This is why dowsing for pipes is possible, as well as tunnels, streams, etc.
For masses of material such as ore beds, it is possible to find those because as the torsion field passes through it, it is altered in one way or another depending on the material. Because of this, your body is equally affected by the sudden change in the field just as you would be by the diffraction pattern over a pipe.
The torsion field is a torque through the axis of a rotating body, which spreads to a transverse wave radiation as you apprach the radius of the rotating body. The axial field travels an infinite distance and appears to travel instantaneously, and is thought by many scientists to be the source of "spooky action at a distance" or quantum entanglement. The radiative field weakens at the same rate as many other waves according to the inverse square law.
This field is not electrical, nor magnetic, nor gravitic, nor any other kind of field you are previously familiar with. It is not zero-point energy and overall the field carries only extremely miniscule energy at all, mostly being useful to carry information in the form of altering the electrical properties of mass.
None of this is revelatory, as all is available to read online, much of it for free (some needs to be translated from Russian or French). I'm currently building a device that can take rough snapshots (and in the future, video feeds) of structures underground, to take out the human error from the equation. 33% of dowsers are sensitive to the signal, providing a foundation for training that they never obtain. 33% are poor dowsers but, believeing themselves to be gifted, provide ample unreliable results and severely throw off the balance of dowsers' reputations. The last 33% cannot dowse and therefore believe the whole mess is fraudulent. This also is covered in the above listed books and articles. If you want to be educated, read the above list. If you wish to continue to believe a specific thing, then by all means skip over the content and chastise me for necroposting.