Conduction, Insulation and Firewalking

Conduction, Insulation and Firewalking

Firewalking is an ancient practice, part of spiritual and religious traditions around the world. Today, it's also become part of leadership retreats and management seminars. The basic theme is mind over matter -- with enough confidence or spiritual training, the fire can't hurt you. And while people who firewalk often report feeling a sense of empowerment or spiritual progress, there's also a physical explanation for what's happening.

Like (Hot) Water Flowing Downhill

A person's ability to firewalk builds on the basic nature of heat. Essentially, heat is energy that moves from warm places to cool places. Much like water flowing downhill, it can't go in the opposite direction. One way heat moves is through conduction, with a warm object transferring its energy to a cool object it touches. The warm object expends its energy and lowers its own temperature in the process, which continues until the objects reach the same temperature or stop touching. Heat also moves as electromagnetic radiation -- that's how heat from a radiator reaches your skin. Finally, heat can move via convection. Warmer regions of a liquid or gas rise while cooler, denser areas fall.

When it comes to firewalking, conduction and radiation are the two methods of heat transfer in play. The firewalker's feet and the embers are touching, so heat moves through conduction. The coals also emit heat as electromagnetic radiation, warming the area near the coal bed.

Hot Coals and Coffee Cups

So if the coals are moving heat into the air and into the firewalker's feet, what keeps people from getting burned?

The secret is in the nature of the coals themselves. Typically, firewalking takes place on a bed of wood embers that have burned down, coating themselves with a thick layer of ash. This ash acts like an insulator, making it harder for the coals to transfer their heat to the walkers' feat. It's like the difference between sticking your finger straight into a cup of hot coffee and wrapping your hand around your coffee mug.

Time is also a factor. Firewalkers tend to move at a brisk pace. They don't run -- so their feet don't dig down into the coals -- but their feet don't spend a lot of time in contact with the embers, either. While they're in contact, the coals raise the temperature of the firewalker's feet through conduction. But since the firewalker quickly moves his or her feet away from the coals, the temperature of the skin typically doesn't have time to rise to a point that it causes injury.

Physics or First Aid?

This doesn't make firewalking foolproof, though. In 2002, 20 restaurant managers attending a conference wound up in the hospital after attempting a firewalk. Another 10 people received first aid at the scene.

The moral of this story? Even though there's a protective padding of physics involved in firewalking, don't try it at home.