A Psi wheel
-like device consisting of a small piece of paper
balanced on the tip of a pointed object. Most common explanations for its actions involve air currents caused by the convection of heated air which move the psi wheel. It is also commonly used in attempts to prove the validity of telekinesis
There are several designs for the shape of the psi wheel, but the most common is an inverted funnel-shaped pyramid. This psi wheel shape may be constructed by creasing a small (around 2 inch by 2 inch) square of paper
lengthwise, height wise, and diagonally both ways, then bending the square slightly along the creases to reach the desired shape.
Another common type of psi wheel is in the shape of a cross made out of a thin sheet of metal such as aluminum or brass. The arms of the cross are anywhere from 1.25 to 2 inches in length,
with a small dimple in the middle so that it can be balanced on something sharp.
This wheel then balances on a small, pointed object such as a thumbtack, needle, or pen cover firmly planted on a flat surface. An object such as a thumbtack or pen cover can stand on its base by itself, however an object such as a needle will need to be rooted in another stable object such as an eraser, sponge,box, or bottle cap in order to provide it with enough stability to hold the spinning wheel on its tip; one design even uses a bottle cap filled with J-B Weld, a two-part epoxy, to hold a needle in place. Sometimes such psi wheels are placed within small glass or plastic containers to prevent random bursts of air from causing spurious movement of the wheel.
The human body maintains its core body temperature by releasing excess heat through the skin into the surrounding air. Thus when very, very warm hands are placed on either side of the psi-wheel, the air around the wheel becomes warmer than the surrounding air. This hot air rises after a long period above the surrounding colder air by convection
, causing a small updraft that pushes on the psi-wheel. The positioning of the hands can manipulate the direction of the draft to cause the wheel to rotate. Any heat source, human or non-human, can reproduce this effect with the appropriate positioning. A problem with this explanation is that in some displays of the spinning psi wheel, the wheel rotates several times, which requires more convection air than possible from normal human hands.
Many experimenters claim after trying this that it is very unlikely that the wheel will move at all or for very long by convection from the user's hands, and there have been several experiments with a psi wheel and a spoon heated beyond the human body temperature, which failed to move the psi wheel at all.