Firewalking For Fun

Southampton University Physics Society's Firewalk; May 11, 1997

by Jim Champion (jdc295@soton.ac.uk)
written 19 Aug 1997

This article is classified "Real"


"Hot footing boffins in burning issue" read the headline in the Southampton
Daily Echo.  Apparently that's what the Physics students at the University
of Southampton were.  (Maybe if their reporter had actually been bothered
to turn up at the Physoc event of the year then they might have thought of
a slightly less corny headline.)  There was no special mental preparation,
no supernatural powers involved and not a pair of asbestos flip-flops in
sight.  Just twelve feet of glowing embers at a temperature of 600 degrees
Celsius and a hundred people only too eager to risk their feet for the sake
of science.

Dr Robin Allen (firewalking expert from the Wessex Skeptics) gave the
pre-walk lecture.  He explained why a bunch of physicists have organised a
spectacle usually associated with Eastern mystics, religious nuts and
blatant con-artists.  Apparently there is no mystery about why one can walk
over coals at temperatures of several hundred degrees C without coming to
any harm, and it's all down to the physics of heat conduction.

"It's like opening the oven to take out a baked cake", he said.
"Everything in the oven is at the same temperature, the air, the metal cake
tin and the cake.  You have no fear of putting your hand in the oven --
that's because the air is a poor conductor of heat and doesn't immediately
burn you.  But the metal cake tin will!"

The wood is a poor conductor of heat -- it only causes burns if your feet
stay in contact for long enough for the heat energy to be transferred.
There are many other factors involved, such as the length of the pit, the
thickness of the soles of your feet, how quickly you walk and the type of
wood being used.  Dr Allen confessed that this particular firewalk was
going to be a bit of an experiment as the wood that would be used was
beech, and he had only ever used oak before.  One hundred and fifty people,
a mixture of physicists, other students and the general public, reassessed
their need to take part.  All the reassurances seemed to scare people even
more, so as a distraction he showed a video clip of a guy who licks red-hot
iron bars for fun.  Compared to that, the task in hand seemed a doddle, and
everyone was out of the physics building like a shot, swarming around the
bonfire site.

While the lecture was in progress a quarter of a ton of beech and rosewood
had been set alight, with the help of some paraffin and copies of the Daily
Mirror.  By the time we arrived, the leaping flames had died down and red
hot embers were being raked out evenly over the pit.  People started to
remove their shoes and socks, following the lead of Dr Allen.  The tension
was mounting, the embers were given a final prod and the firewalking
physicist carefully wiped his feet on a towel -- hot embers stick to wet
feet, and the way to avoid nasty burns is to make as little contact with
the hot stuff as possible.

The crowd held its breath as Dr Allen crunched his way across the
far-from-cool pit, following his own advice of brisk light steps, with toes
curled upwards and no hanging around.  After five strides he was onto the
sopping wet blanket at the far end.  The gathered throng burst into
applause and he ran back and had a second go at it.  Amazement and relief
showed on people's faces -- it was possible.  There was a short pause
before some guy decided this was not a cruel trick and had a go himself.
Suddenly everyone wanted a go.  As the pensioners left, having seen what
they came to see, a constant stream of willing volunteers donated their
pound to the Wessex Cancer Trust and made the journey across the 600
degrees C terrain.

To the flash of the press' cameras, people went across alone, three-legged,
in a conga, and generally very quickly.  No one attempted a handstand,
cartwheel, forward roll or back flip -- and especially not the Monkees
walk.  After an hour of this application of thermodynamics most of the
experimenters grew tired of this amazing feat that was actually quite easy
to perform.  Only a few die-hard physics students remained, trying to set a
record for going across the most times.  At 10pm the security guards
declined the offer to be the last ones to go over and the
once-quarter-of-a-ton of wood was finally extinguished.

At the recovery session in the Union bar everyone was busy lying about how
brave they had been.  No-one seemed to have any injuries -- the only
casualty of the evening was a packet of Hob-Nob biscuits that had fallen
from the pocket of a firewalker.  The profit for charity added up to 100
pounds.  Riding high on a wave of firewalking-induced self confidence, I
was confronted by a guy who said "So you walked across hot embers; what's
so amazing about that?" This was a bit deflating, to say the least, and I
realised that some people don't need a sound demonstration of the
application of physics to remove the mysticism from the spectacle of
walking on fire.

N.B. Don't try this one at home.

See also:
  • Fire
  • Celsius, Anders

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