Sparks flew outside St David’s lecture theatres last week as students were invited to take part in a firewalking demonstration.
Physics expert, Dr John Campbell, hosted the event, which was preceded by a public lecture on why we’re able to safely walk on the coals, which were around 900 degrees Celsius. Campbell explained that a lot of the art is down to safety precautions, organisation, an experienced pitman and timing.
“Every Kiwi who’s had an open fire knows that when a spark flies out of the fire and onto the carpet, we’re able to pick it up and throw it back in,” explained Campbell. “We know, from what used to be everyday experience, that you can use your fingers to touch red-hot charcoal for about a second.”
Campbell said the general rule is that our living tissue “mustn’t reach a temperature of more than 55 degrees Celsius.” With charcoal, “you have about a second of contact time” before this occurs.
The reason we can walk on coal at such temperatures is because “there’s only one foot down at a time, and it’s in contact with the ground for about half a second.” Therefore, you can walk four paces on red-hot charcoal and you’re only just getting towards the limit of the damage.
However, this only applies to the bare-end surfaces of the body where there is a lot of wear and, therefore, a very thick layer of dead skin. For example, our fingers and the soles of our feet.
Campbell, who has been hosting such events since 1989, said he began the talks around the time when firewalkers were deemed fascinating. “It was the usual nonsense, [they’d say] ‘give us $200 and we’ll train you to control your mind so that you can walk over red-hot charcoal without feeling pain’. That’s all just hogwash,” he said.
He and his undergraduate students then had a trial with the coals, and held their first public talk at a national skeptics conference.
Campbell has held six of the talks in Dunedin, and said he waits until there is a “new generation of students” who are yet to hear the science behind it.
University of Otago student, Levi Bourke, who walked across the coals last Monday, said it was “a little bit stingy … but it was certainly an experience”.
