“No Thing Coal” (Fire walking)

Fire walking could more accurately be referred to as coal brisk-pacing. It refers to traipsing barefoot across hot coals, rocks, or cinders without suffering harm. It is often employed in religious rituals or in New Age mind-over-matter seminars.

However, there is nothing mystical about it. It is merely conductivity and physics in action. While the objects themselves are hot, they conduct heat poorly. Therefore, someone spending just a few seconds crossing the pit will usually escape unscathed. By way of comparison, imagine an oven set at 350 degrees for baking macadamia nut cookies. Mmmmmm, cookies. After a few minutes, both the air inside the oven and the pan that houses the cookies will be at the same temperature. But while one could safely put one’s hand in the oven, touching the pan would be extremely painful and potentially harmful. That’s because air has a low heat capacity and little ability in the thermal conductivity department. Metal, by contrast, being much denser than air, is an efficient conductor of heat and would burn any idiot who touches it.

Bob Nixon of Australian Skeptics explains, “The difference comes from the ability of various substances to conduct or transfer heat. Air is a very poor conductor of heat, (whereas) metal conducts heat with great efficiency, even though the temperate of the oven air and the container are the same.”

As this relates to fire-walking spectacles, 1,100-degree coals will not usually burn a person’s feet, provided the participant performs more of a jaunt than a leisurely stroll. This is because coals have a low heat capacity and they serve as good thermal insulators. In addition, ash remnants from the burnt charcoal is likewise a poor heat conductor. Also, firewalkers often wet their feet beforehand, which makes burns even less likely.

Combine the poor heat conductivity with the scant time spent crossing the pit and one ends up with a seemingly miraculous movement over burning coals.

“The average human foot will happily be in contact with a glowing wood coal for about a second before sufficient heat is transferred to burn the flesh,” Nixon said. “The average step takes about half a second so for most people, so it is possible to take two steps with each foot before a dangerous amount of heat has built up.”

Burns can still occur under specific circumstances, i.e. a person with thin soles taking too much time to cross on coals that are hotter than usual. But this confluence seldom occurs since those running the show take steps to avoid it and they give explicit instructions to the walkers on how to cross.

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