Bei National Geographic lernt man verschiedene Begründungen kennen, warum man sich nicht die Füße verbrennt, wenn man über glühende Kohlen geht.

"...David Willey [a physics instructor and an expert on the science of fire walking at the University of Pittsburgh in Pennsylvania] ... said people are able to walk across a bed of burning coals because "wood is a lousy conductor."
...
In fire walking, a person's feet, which Willey said are also poor conductors, touch ash-covered coals. Since the fire walker is indeed walking, the time of contact between feet and coals is minimal—too quick for the coals to burn or char the feet, Willey said...."
(Quelle: National Geographic)

Damit man aber auch die andere Seite hört, gibt es da noch mehr Erklärungen, die mehr in Richtung "Motivationskünstler"etc. gehen:

"...
According to Burkan [founder of the Firewalking Institute of Research and Education in Twain Harte, California. He promotes himself as the creator of the U.S. fire-walking movement, which he says dates to 1977], the basic physical principle behind fire walking is the same that allows an egg to boil in a paper cup when placed atop red-hot coals. The boiling water keeps the cup at 212 degrees Fahrenheit (100 degrees Celsius)—hundreds of degrees cooler than paper's burning point.

Burkan says that circulating blood likewise keeps the flesh on a fire walker's feet from reaching its burning point—as long as the walker is relaxed enough to allow strong blood flow and as long as the walker keeps walking. "What controls [the ability to fire walk] is more than physics, it's your state of mind," Burkan said. (Quelle: National Geographic)

Varzil findet das alles ganz spannend und ist fest entschlossen, keine der Theorien an den eigenen Füßen auszuprobieren, solange man um das Feuer noch herumlaufen kann ...