The Physics of FirewalkingS

Last Thursday, close to two dozen participants at a motivational seminar hosted by Tony Robbins suffered burns on their feet, while attempting to tromp across lanes of red-hot coals. So what did these burn victims do wrong?

The Associated Press reports that most of those injured sustained second- and even third-degree burns, but event organizers have since released a statement claiming that 6,000 attendees walked across the coals that day and emerged from the embers unscathed. Educate yourself on the physics of firewalking — here's what you need to know to keep from getting burned.

The first and most important thing that you need to understand about firewalking is that it's not magic. That might sound obvious, but firewalking's ties to religious, mystical, and paranormal explanations date back thousands of years, and persist to this day in the form of seminars like Tony Robbins' "Unleash the Power Within" event (which, speaking of getting burned, participants paid as much as $2,000 to attend). Don't believe me? Here's a sample of what seminar attendees had to say about their firewalking experiences:

"It's amazing what your mind can do when you get into the right state" said one participant. "Look into the power within yourself, and focus on just walking on the fire," declared another.

The Physics of FirewalkingS

Bullshit. Firewalking isn't about mind over matter; it's about basic physics, and moving yourself across that bed of coals posthaste. The "mystery" behind firewalking can be laid bare by examining a physical property known as thermal conductivity. When scientists talk about an object's conductivity, they're referring to its ability to transfer energy in the form of heat to an object with which it has come into contact. In the case of firewalking, we're interested in the transfer of heat from the hot coals to your naked feet.

Coals, woodchips and similar combustibles are made up almost entirely of carbon, and it just so happens that carbon is positively miserable at conducting heat. Most metals, by comparison, are orders of magnitude more efficient at transferring heat than a smoldering coal or wood chip; if you've ever burnt your hand on a hot frying pan, you have an appreciation for just how conductive metal can be.

A layer of ash atop the coals serves as an additional protective barrier. Like the coals beneath it, ash is a poor conductor of thermal energy (so poor, in fact, that it has a history of use as insulation material in ice boxes). Add to this the fact that the ash is no longer producing any heat itself, and one can begin to appreciate how walking over a bed of 2000-degree coals might be possible.

All that being said, it's important to remember that these coals are hot. There's no two ways about it — if you dawdle, you're going to get burned. "It is neither necessary nor advisable to run, a brisk walk is reported to work best, with each step taking half a second or less," explains University of Pittsburgh physicist David Willey, who has made a habit of demonstrating physical concepts to his students by walking across hot coals, dipping his hand in molten lead, and ambling over broken glass. "During a fourteen foot firewalk then, each foot will be in contact for a total time of a second or so."

If I had to guess what happened with the people who suffered burns Thursday night, I'd say that they spent too much time looking into "the power within themselves" and "focusing on walking on the fire," and not enough time focusing on actually getting themselves off the coals.

[The University of Pittsburgh | National Geographic | The Committee for Skeptical Inquiry]

Top image via Shutterstock; Firewalker via