Firewalking

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Firewalking is the act of walking barefoot over a bed of hot embers or stones. It has a long history in many cultures as a test or proof of faith, and is also used in modern motivational seminars and fund-raising events.


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[edit] History

Firewalking is practiced

Walking on fire has existed for a few thousand of years with records dating back to 1200 B.C.[1] Cultures across the globe, from Greece to China, used firewalking for rites of healing, initiation, and faith.[1] Firewalking became popular in America during the 1970s when author Tolly Burkan began a campaign to demystify the practice. He offered evening firewalking courses that were open to anyone in the general public. The demand for firewalking classes became so great that in 1984 Burkan began training instructors.[2] Recently, in the United States, firewalking is used by businesses to build teamwork and as a so-called alternative health remedy.[1]

[edit] Explanation

When two bodies of different temperatures meet, the hotter body will cool off, and the cooler body will heat up, until they are separated or until they meet at a temperature in between.[3] What that temperature is, and how quickly it is reached, depends on the thermodynamic properties of the two bodies. The important properties are temperature, density, specific heat capacity, and thermal conductivity.

The square root of the product of thermal conductivity, density, and specific heat capacity is called thermal effusivity and tells how much heat energy the body absorbs or releases in a certain amount of time per unit area when its surface is at a certain temperature. Since the heat taken in by the cooler body must be the same as the heat given by the hotter one, the surface temperature must lie closer to the temperature of the body with the greater thermal effusivity. The bodies in question here are human feet, which mainly consist of water, and burning coals.

Due to these properties, David Willey, professor of physics, says he believes firewalking is explainable in terms of basic physics and is not supernatural or paranormal.[4] However, he adds, "The 120 foot walk done by Sara Raintree and Jim Jarvis, and reports of longer walks and people remaining stationary for extended periods on the coals are currently under investigation by the author." Willey notes that most fire-walks occur on coals that measure about 1,000 degrees Fahrenheit (500 degrees Celsius), but he once recorded someone walking on 1,800-degree (1,000 °C) coals.[1]

[edit] Factors that prevent burning

Factors that act together to prevent the foot from burning
  • Water has a very high specific heat capacity (4.18 kJ/K kg), whereas coals have a very low one. Therefore the foot's temperature tends to change less than the coal's.
  • Water also has a high thermal conductivity, and on top of that, the blood in the foot will carry away the heat and spread it. On the other hand, coal has a poor thermal conductivity, so the hotter body consists only of the parts of the coal which is close to the foot.
  • When the coal cools down, its temperature sinks below the flash point, so it stops burning, and no new heat is generated.
  • The coals are often covered with ash, which is a poor heat conductor.
  • The coals are a very uneven surface, and the actual surface area of foot touching the coals is very small.
  • Firewalkers do not spend very much time on the coals, and they keep moving.
  • Calluses on the feet may offer an additional level of protection, even if only from pain.

[edit] Risks when doing firewalking improperly

There are risks when doing firewalking improperly
  • People have burned their feet when they remained in the fire for too long, enabling the thermal conductivity of the coals to catch up.
  • Foreign objects in the coals may result in burns. Metal is especially dangerous since it has a high thermal conductivity.
  • Coals which have not burned long enough can burn feet more quickly. Coals contain water, which increases their heat capacity as well as their thermal conductivity. The water must be evaporated already when the firewalk starts.
  • Wet feet can cause coals to cling to them, increasing the exposure time.

Therefore, even if firewalking is explained with simple physics, there are still hazards. Notably in 2002, twenty managers of the KFC fast food chain in Australia received treatment for burns caused by firewalking.[5] However, this exercise in firewalking was practiced over timber, a more efficient heat conductor than coal.[6]

[edit] Records

The "world's longest firewalk" record of 220 feet, accomplished by Amanda Dennison in Alberta, Canada on June 15, 2005, was broken by Scott Bell who walked 328 feet in Wuxi, China on November 28, 2006.

[edit] References

  1. ^ a b c d Binns, Corey. "World's Watch and Learn: Physics Professor Walks on Fire", Livescience.com, 14 August 2006. Retrieved on 2007-04-13. 
  2. ^ Loring Danforth, Ph.D., Firewalking and Religious Healing (1989), Princeton University Press. ISBN 0-691-02853-2. Chapter 8, page 261. See Amazon Online Reader: Firewalking and Religious Healing.
  3. ^ "Can you walk on hot coals in bare feet and not get burned?", The Straight Dope, 14-Jun-1991. Retrieved on 2007-04-13. 
  4. ^ Willey, David. "Firewalking Myth vs Physics", University of Pittsburgh, 2007. Retrieved on 2007-04-13. 
  5. ^ Kennedy, Les. "KFC bosses aren't chicken, but they sure are tender", The Age, February 28 2002. Retrieved on 2007-04-13. 
  6. ^ Mitchell, 1987.
  • Xygalatas, Dimitris, “Firewalking in the Balkans: High Arousal Rituals and Memory”, in: Ivan Czachesz (ed.), Changing Minds: Religion and Cognition through the Ages, Groningen Studies in Cultural Change Series, Leuven: Peeters forthcoming.
  • Xygalatas, Dimitris, “Firewalking and the Brain: The Physiology of High-Arousal Rituals”, in: Joseph Bulbulia, Richard Sosis, Erica Harris, Russell Genet, Cheryl Genet, and Karen Wyman (eds.) Evolution of Religion: Studies, Theories, and Critiques, Santa Margarita, CA: Collins Foundation Press 2007, pp. 189-195.
  • Xygalatas, Dimitris, “Introduction to the Cognitive Science of Religion”, in the Greek Translation of Harvey Whitehouse, Modes of Religiosity (Greek title: Τύποι Θρησκευτικότητας, Θεσσαλονίκη: Βάνιας 2006), pp. 9-92.

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