Walking On Hot Coals? BS or what.
Chip Pearson
Recently my girlfriend and I got into a discussion about people who claim to
walk on hot coals without injury. My feeling is that it is total bullshit, a
hoax. She's more into the "mind over matter" new age stuff (she's got a few
crystals scattered around), and thinks that it is done frequently "on those
islands somewhere in the Pacific". (Geography is not her strong point.)
I suppose that if I had to, I could accept that the fire-walker could
temporarily block out the physical pain, but not physical tissue damage to
the feet. I suppose the guy could walk fast enough so that each foot is in
contact with the coals for a short enough time, but she claims to have seen
film of someone walking real slowly over the coals.
I know I'm right, but I need proof!
Chip
Brian Trosko
Chip Pearson <cpea...@gvi.net> wrote:
: the feet. I suppose the guy could walk fast enough so that each foot is in
: contact with the coals for a short enough time, but she claims to have seen
: film of someone walking real slowly over the coals.
: I know I'm right, but I need proof!
You are wrong; firewalking is well documented, with at least one college
physics professor demonstrating the phenomenon in the classroom.
It works because of film boiling. Heat up a metal skillet and drop a drop
of water into it; the water won't boil away instantly, but instead
skitters and dances on the skillet. This is because a thin film of water
boils, and this thin layer of steam insulates the rest of the water from
the heat.
When someone steps barefoot on hot coals, the layer of sweat on the bottom
of their feet forms a protective layer. This isn't mind-over-matter or
bullshit mysticism; it's physics.
Chip Pearson
Really? That pretty cool. But is there enough moisture on the bottom of the
fire-walker's feet to create enough steam to provide this level of
insulation? When you drop a drop of water on to the hot skillet, some
(signficant?) amount of it is converted to the steam that creates the
insulating layer. It seem that your feet would have to be AWFULLY wet to get
the same effect. This there a url for more info?
Chip
Brian Trosko wrote in message <6n3qc9$9...@nntp02.primenet.com>...
Grant Edwards
Brian Trosko (btr...@primenet.com) wrote:
: Chip Pearson <cpea...@gvi.net> wrote:
: : the feet. I suppose the guy could walk fast enough so that each foot is in
: : contact with the coals for a short enough time, but she claims to have seen
: : film of someone walking real slowly over the coals.
:
: : I know I'm right, but I need proof!
:
: You are wrong; firewalking is well documented, with at least one college
: physics professor demonstrating the phenomenon in the classroom.
: It works because of film boiling. Heat up a metal skillet and drop a drop
: of water into it; the water won't boil away instantly, but instead
: skitters and dances on the skillet. This is because a thin film of water
: boils, and this thin layer of steam insulates the rest of the water from
: the heat.
Steam will burn your feet pretty damn fast.
: When someone steps barefoot on hot coals, the layer of sweat on the bottom
: of their feet forms a protective layer. This isn't mind-over-matter or
: bullshit mysticism; it's physics.
You can walk on hot coals even with dry feet. It's mostly just
because coals have both low heat capacity and conductivity. There's
not much thermal mass, and what limited heat is there can't be
conducted quickly to your feet.
Try walking on hot iron. Even with wet feet you'll be in the hospital
after the first step.
--
Grant Edwards
Carl Fink
On 27 Jun 1998 15:06:01 -0700, Brian Trosko <btr...@primenet.com> wrote:
>It works because of film boiling. Heat up a metal skillet and drop a drop
>of water into it; the water won't boil away instantly, but instead
>skitters and dances on the skillet. This is because a thin film of water
>boils, and this thin layer of steam insulates the rest of the water from
>the heat.
Well, it works, but not for that reason. It works because the heat
capacity of hot coals is very low -- they don't walk on fires while
they're actually burning, they walk on "coals" -- that is, embers left
after the active fire has gone out. They're extremely hot, but the
actual amount of energy there is quite low because the mass of the
coal is small. (It's mostly air by that point.)
--
Carl Fink ca...@dm.net
Q. Why do some people take astrology seriously?
a. Because they have unusually small brains. --Dave Barry
Donald Billgren
>It works because of film boiling. Heat up a metal skillet and drop a drop
>of water into it; the water won't boil away instantly, but instead
>skitters and dances on the skillet. This is because a thin film of water
>boils, and this thin layer of steam insulates the rest of the water from
>the heat.
>
>of their feet forms a protective layer. This isn't mind-over-matter or
>bullshit mysticism; it's physics.
Our local university physics professor has demonstrated it himself and
taught a number of interested people to do it, as documented on TV. Another
important factor in making this possible, he points out, is that the coals,
while being hot, have a low heat capacity - you would thus probalby get
injured trying the same thing walking on red hot iron.
Brian Trosko
Carl Fink <ca...@dm.net> wrote:
: >of water into it; the water won't boil away instantly, but instead
: >skitters and dances on the skillet. This is because a thin film of water
: >boils, and this thin layer of steam insulates the rest of the water from
: >the heat.
: Well, it works, but not for that reason. It works because the heat
: capacity of hot coals is very low -
That is a contributing factor, but is not the sole reason. The same
professor who has firewalked in class (can't remember his name, but he's
my physics textbook author), also has performed many demonstrations where
he dips his hand in water, and then plunges it into a bath of molten lead,
which has a significantly higher heat capacity than wooden coals.
I believe the formal name is the Ledenfrost Effect.
Randall Joiner
"Chip Pearson" <cpea...@gvi.net> wrote:
>Really? That pretty cool. But is there enough moisture on the bottom of the
>fire-walker's feet to create enough steam to provide this level of
>insulation? When you drop a drop of water on to the hot skillet, some
>(signficant?) amount of it is converted to the steam that creates the
>insulating layer. It seem that your feet would have to be AWFULLY wet to get
>the same effect. This there a url for more info?
>
>Chip
There's a book that discusses this, and many other topics, explaining
the scientific how's and why's of things like this.
"Why People Beleive Weird Things: Pseudoscience, superstition, and
other confusions of our time" by Michael Shermer.
It's a well written book, with alot of time and thought placed into
it. A good primer for a beginning Skeptic.
Randall Joiner
Rodger Coghlan
Chip, the explanation that I have heard is that it is the difference
between temperature and heat content (ie, say you are baking bread in an
oven at 450 degs - You can stick your hand into a 450 oven with no
problem, you can touch the loaf of bread that is 450, but if you touch
the metal rack - you are immediately burned. (I have also heard some
people report that their feet blistered the next day.) Those people walk
pretty fast across the coals so that the feet never spend a lot of time
on the coals and the coals are pretty well burned down to ash. I was at
a meeting of NWSkeptics in Seattle with a couple of guys who tried it -
one went through the class and the other who joined in without taking
the class, and both walked the coals without blisters (proving that
there was nothing in the class that was responsible for the feat). So,
firewalking is real but it is just a trick (so to speak).
Rodger
Chip Pearson wrote:
>
> Recently my girlfriend and I got into a discussion about people who claim to
> walk on hot coals without injury. My feeling is that it is total bullshit, a
> hoax. She's more into the "mind over matter" new age stuff (she's got a few
> crystals scattered around), and thinks that it is done frequently "on those
> islands somewhere in the Pacific". (Geography is not her strong point.)
>
> I suppose that if I had to, I could accept that the fire-walker could
> temporarily block out the physical pain, but not physical tissue damage to
> the feet. I suppose the guy could walk fast enough so that each foot is in
> contact with the coals for a short enough time, but she claims to have seen
> film of someone walking real slowly over the coals.
>
> I know I'm right, but I need proof!
>
> Chip
--
All opinions expressed are Mine
(mea culpa, mea culpa, Mea maxima culpa)
Carl Fink
On 28 Jun 1998 18:08:00 -0700, Brian Trosko <btr...@primenet.com> wrote:
>That is a contributing factor, but is not the sole reason. The same
>professor who has firewalked in class (can't remember his name, but he's
>my physics textbook author), also has performed many demonstrations where
>he dips his hand in water, and then plunges it into a bath of molten lead,
>which has a significantly higher heat capacity than wooden coals.
Irrelevant -- firewalkers don't do that, and in fact people with
sweaty feet are reported to get *worse* burns because the hot embers
stick to their feet.
--
Carl Fink ca...@dm.net
"God never bothered to patent his stuff." --Calvin
Brian Trosko
Carl Fink <ca...@dm.net> wrote:
: >That is a contributing factor, but is not the sole reason. The same
: >professor who has firewalked in class (can't remember his name, but he's
: >my physics textbook author), also has performed many demonstrations where
: >he dips his hand in water, and then plunges it into a bath of molten lead,
: >which has a significantly higher heat capacity than wooden coals.
: Irrelevant -- firewalkers don't do that,
While you are correct that they do not, you are incorrect that it is
irrelevant. The film-boiling effect is the same, and it protects hands
from molten lead and feet from hot coals in the same way.
My textbooks are not near to hand, but I will be happy to cite from them
in the near future, sometime after July 4th.
: and in fact people with
: sweaty feet are reported to get *worse* burns because the hot embers
: stick to their feet.
I had not heard that. In fact, the professor I speak of, whose name I
still cannot remember, was burned while firewalking only when his
nervousness about performing the feat subsided, and his feet were not
sweaty for the attempt.
Lee Oliver
In article <6n452q$199$1...@carlf.dialup.access.net>, Carl Fink
<ca...@panix.com> writes
>
>Well, it works, but not for that reason. It works because the heat
>they're actually burning, they walk on "coals" -- that is, embers left
>after the active fire has gone out. They're extremely hot, but the
>actual amount of energy there is quite low because the mass of the
>coal is small. (It's mostly air by that point.)
I'd like to add that if they were to try the same trick walking on a
sheet of steel heated to the same temperature as the coals, they'd be
seriously injured very quickly (probably), as steel would a have a much
greater heat capacity and would deliver a lot of heat to the skin.
Notice how nobody has ever demonstrated fire walking on anything other
than hot coals.
The real trick is just psyching oneself up enough to do it, which is
still pretty impressive in itself.
--
Lee Oliver West Yorkshire, UK
<l...@sniper.demon.co.uk> http://www.sniper.demon.co.uk/
Carl Fink
On 29 Jun 1998 19:44:01 -0700, Brian Trosko <btr...@primenet.com> wrote:
>My textbooks are not near to hand, but I will be happy to cite from them
>in the near future, sometime after July 4th.
My sources are perhaps somewhat closer -- do you really want to play
"dueling argumentum ad authoritem"?
Care to experiment?
BTW, as a biology major I might point out the lack of sweat glands on
the soles of the feet.
The phenomenon you describe *does* explain fire-EATING, though.
--
Carl Fink ca...@dm.net
Manager, Dueling Modems Computer Forum
<http://dm.net>
Douglas Natelson
Brian Trosko <btr...@primenet.com> wrote:
>That is a contributing factor, but is not the sole reason. The same
>professor who has firewalked in class (can't remember his name, but he's
>my physics textbook author), also has performed many demonstrations where
>he dips his hand in water, and then plunges it into a bath of molten lead,
>which has a significantly higher heat capacity than wooden coals.
>
>I believe the formal name is the Ledenfrost Effect.
The professor is Jearl Walker, at Cleveland State I believe, and
you're right about the name of the effect. Another striking
demonstration of the Ledenfrost Effect: pour a cup of liquid nitrogen
on the floor, and watch what the blobs of LN2 do, skittering around
just above the surface.
DN
Ron Thomas
On Mon, 29 Jun 1998 18:02:05 GMT, Rodger Coghlan <rod...@oup-usa.org>
wrote:
I was at
>a meeting of NWSkeptics in Seattle with a couple of guys who tried it -
>one went through the class and the other who joined in without taking
>the class, and both walked the coals without blisters (proving that
>there was nothing in the class that was responsible for the feat). So,
>firewalking is real but it is just a trick (so to speak).
>
>There must be a psychological element about this as well. What about the old chestnut of the University student
who was being put through some initiation ceremony, was blindfolded,
and told he was about to be branded with a red-hot iron. A n
ice-cold iron was in fact applied, but the student came out in a huge
blister and a severe burn. Is this possible? And could there be
any connection with the coal-walking?
Ron
Ron Hunsinger
In article <359aa43...@news.force9.net>, r...@ronthomas.force9.co.uk
(Ron Thomas) wrote:
> There must be a psychological element about this as well. What about
the old chestnut of the University student
> who was being put through some initiation ceremony, was blindfolded,
> and told he was about to be branded with a red-hot iron. A n
> ice-cold iron was in fact applied, but the student came out in a huge
> blister and a severe burn. Is this possible? And could there be
> any connection with the coal-walking?
I don't know about the blisters, but the student could very well believe he
was touching something very hot.
You skin contains sensors for "warm" and "extreme temperature". There is an
exhibit at the Exploratorium here in San Francisco that demonstrates this
very nicely. There is a cylinder with metal coils wound around it. One of
the coils is very cold, and wraps around about 2/3 of the cylinder's length
from one end. The other coil is mildly warm, and wraps around 2/3 of the
cylinder's length from the other end.
What that means is that the first third of the cylinder has only the cold
coil wrapped around it. Put your hand there, and it feels cold. The last
third of the cylinder has only the warm coil wrapped around it. Put your
hand there, and it feels warm.
But the middle third of the cylinder has both coils, alternating. Put your
hand there, and the temperature sensors in your skin report "extreme" and
"warm", which your mind interprets as "very hot". It takes an effort to
keep your hand there.
-Ron Hunsinger
tim
In article , "Chip Pearson" <cpea...@gvi.net> writes:
>
> I suppose that if I had to, I could accept that the fire-walker could
> temporarily block out the physical pain, but not physical tissue damage to
> the feet.
You're missing the possibility that walking on hot coals doesn't cause
any physical tissue damage.
By the way, I see that in another post someone has mentioned the sweat
effect. I doesn't take that much water at all. A good trick I was
taught while glassblowing is that if you don't know if a piece of
glass is hot (and it really is absolutely impossible to tell whether a
piece of glass is at room temperature or several hundred degrees just
by looking), lick your fingers before touching it. In the event you
were wrong, you hear a sizzling sound as you touch it and quickly yank
your hand away; it doesn't even feel hot at all. Unfortunately, I
must say if you don't lick your fingers, you get a rather nasty burn
from even the briefest touches. Another professor who likes to
demonstrate this effect has been known to pour water over his hand
then stick it in molten lead, then pull it out unharmed. Oh, while
I'm at it, I've also stuck my finger in liquid nitrogen, and poured it
on my hand before. You get protected by a similar effect :-)
As a home experiment in how poorly gases conduct heat, preheat your
oven to 500 degrees. Open it, and stick your hand inside. While it
feels warm, your hand suffers no damage despite being in contact with
500 degree air. Now consider what would happen if you touched the 500
degree metal racks instead :-)
(DON'T TRY ANY OF THIS AT HOME :-))
---------------------------------------------------------------------------
Tim Hollebeek | "Everything above is a true
email: t...@wfn-shop.princeton.edu | statement, for sufficiently
URL: http://wfn-shop.princeton.edu/~tim | false values of true."
Randall Joiner
t...@wagner.Princeton.EDU (tim) wrote:
[snap]
>As a home experiment in how poorly gases conduct heat, preheat your
>(DON'T TRY ANY OF THIS AT HOME :-))
*boggle*
t...@wfn-shop.princeton.edu
In article <35a0f883....@news.america.net>, rljo...@mindspring.com writes:
> t...@wagner.Princeton.EDU (tim) wrote:
> [snap]
>
> >As a home experiment in how poorly gases conduct heat, preheat your
>
>
lots more stuff deleted here, but if he admitted that, it would be
completely obvious how pointless his post was.
>
> >(DON'T TRY ANY OF THIS AT HOME :-))
>
> *boggle*
Obviously refering to the more dangerous stuff near the end. Now go away.