Fire-walking

[Please could one of the firewalkers on the net contribute a paragraph or two for this section. PAJ]

6.1: Is fire-walking possible?

Yes. It is possible to walk on a bed of burning wood without being hurt.

6.2: Can science explain fire-walking?

There are a number of theories which have been put forward to explain firewalking. Any or all may be the explanation for a particular event.

• The dry wood coals used by firewalkers conduct heat very poorly. The coal itself may be very hot but it will not transfer that heat to something touching it.

• The coals are a very uneven surface, and the actual surface area of foot touching the coals is very small. Hence the conduction of heat is even slower.

• Wood coals have a very low heat capacity, so although they are very hot there is actually not much heat energy to be transferred to the foot.

• Firewalkers do not spend very much time on the coals, and they keep moving. Jan Willem Nienhuys <wsadjw@urc.tue.nl> adds that about 1 second total contact time per foot seems on the safe side.

• Blood is a good conductor of heat. What heat does get through is quickly conducted away from the soles of the feet.

• The "Leidenfrost" effect may play a part. This occurs when a cold, wet object (like a foot) touches a hot, dry object (like a burning coal). The water vaporises, creating a barrier of steam between the hot and cold objects. Hence the two objects do not actually touch and evaporation from the cold object is much slower than might otherwise be expected. Since steam is a relatively poor conductor of heat the foot does not get burned. Jearl Walker, of Scientific American's "The Amateur Scientist" column, explains the Leidenfrost effect in the August 1977 issue; he walked across coals unharmed and attributes this to the Leidenfrost effect. Other scientists believe that the Leidenfrost effect is unimportant in firewalking.

Firewalking is usually done in a religious or spiritual context. This would tend to reduce the level of pain experienced by firewalkers without affecting the amount of physical damage done to the feet.

Some firewalkers put forward mystical explanations of why firewalking is possible without serious physical harm. A few skeptics have challenged these firewalkers to stand on hot metal plates instead of coals. Others have pointed out that making such a challenge in the belief that the firewalker would be seriously hurt is of dubious morality.

Jay Mann from New Zealand writes:

> The NZ CSICOP had a mass firewalk at its annual meeting in
> Christchurch about 5 years ago.  We had a lengthy afternoon talk by a
> professor of physics, complete with demonstrations of tossing hot
> bread loaves back and forth. The fire was built in mid-afternoon, and
> the firewalk took place after the society banquet, that is, about 10
> p.m.
> 
> One *never* walks on live coals.  The fire is lit hours before the
> actual walk. Large burning coals are removed. The firebed is carefully
> raked to provide a continuous smooth layer of ashes over all burning
> embers. By this time, it is dark and the firebed is seen to glow
> ominously.  It is still hot, and potatoes can be cooked in the ashes. On
> the other hand, the rate of heat transfer through the ash is
> time-limited.  If participants take steady strides, even city-folk with
> soft soles can manage at least five steps.  In the Christchurch version,
> we stepped in a small puddle of water at the end of the firewalk; I have
> seen at least one description of a "commercial" firewalk where cooling
> water was also provided.
>  
> In Christchurch, dozens of people went across.  Some went back for two
> or three passages.  The bed was re-raked periodically to restore the ash
> layer. There were two or three minor burns and blisters the next day,
> mostly people who had kicked embers up between their toes.  Having done
> a firewalk is a wonderful conversational topic, and most people will not
> believe that you didn't have some sort of mystic faith and determination
> to "protect" your body.
>  
> Denis Dutton, then president of the NZSCICOP, later went to New Guinea
> on a professional trip.  There he trained one local tribe in firewalking
> as way to attract the tourist dollar.  The first few firewalkers, in a
> private test, were cautious, but eventually the whole tribe-- man,
> woman, and child -- gleefully ran through the "fire".  For public
> performance, the tribe added a lot of magical incantations and rituals.
> Denis asked them how they would explain their knowledge of the trick.
> They replied that they would say "an alien from the skies came and
> taught us".  You can imagine that people with tough soles from barefoot
> walking could tolerate more exposure soft-soled city people.