The Scientific Method
The hypothesis inherent in Physical Testing is that a spirit can move a glass or pointer. Tests are based on eliminating all other possible ways that the glass in a séance is moved.
This form of testing basically revolves around the attempt to detect (and measure) any "unnatural" force exerted onto the glass or pointer used in a séance. To detect this force you must somehow exclude the forces exerted by the séance participants. An obvious test would be whether the glass moves without anyone touching it.
There are definitely stories of things moving by themselves. My beloved tells a story of a room in her parents' house in which things moved unaided. I, however, observed nothing in the time that I stayed in that house. The point is that one of the demands I place on testing is that it should be reproducible, by anyone. It is no good to say "Oh it moves when you are not here" whenever a skeptic is around. In any logical argument you would have to seriously consider delusional behaviour when confronted by someone who says he or she sees things that you cannot.
There are many people who tell stories of glasses not moving at all than those who tell of glasses moving mysteriously. I personally observed a moving glass stop dead when my brother and I removed our hands from it. I therefore suggest that it is entirely likely that some sort of physical contact with a glass or pointer in a séance is required for movement.
So, if people have to touch the glass to get it to move, then how do you eliminate the possibility that they are actually moving the glass themselves?
One of the best "home remedies" I have heard is one in which the glass was placed on soap and the participants just lightly touched the glass. The reduction of friction would make any attempt by a participant to manipulate the session (even unconsciously) quite apparent.
Other suggestions included variations on seating arrangements to avoid having any one person manipulate the glass. I do recall that during my séance, after my beloved had left, the glass did move away from my bother and I as easily as in any other direction.
I am indebted to a researcher in Melbourne, James (whose other name is buried somewhere on my reformatted hard drive), who sent me an image of an octotron, a device used to eliminate the effect of participants efforts to control the movement of a pointer. It does not look like something I could knock together in the garage!
One major problem I see with the physical testing approach is that it is based on an assumption that I have not been able to support, that is that there is some physical force exerted by the "spirit". As is mentioned on the spirit page, expecting a spirit to answer questions is enough without the introduction of some sort of poltegeist capability. For a force to be exerted some energy must be expended. If a spirit pushes a glass, even very lightly, where does the energy come from?
It is very remotely possible that the necessary energy could be drawn from the air. This would result in the air becoming cooler, a phenomenon which is reported but more likely to be psychological rather than thermological. If however, this is the mechanism, it should be possible to measure a change in air temperature if the conditions of the experiment are sufficiently controlled.