27 Comments on “Gene Firewalker”   rss feed

1. Dan on Apr 28th, 2006 at 2:41 pm

   I guess at least you have to walk pretty fast or you’ll get burned, no?
   I would love to see some actual numbers, as some friends don’t believe me when I tell them that it’s straightforward science and not “willpower”, “god”, etc.

2. citrine on Apr 28th, 2006 at 3:08 pm

   Is this the hazing ritual for new faculty?

3. Rob Knop on Apr 28th, 2006 at 3:13 pm

   The mystic powers you need are very similar to the mystic powers needed to do the “bowling ball in the face” demo to a freshman physics class. I tried to do this as a TA at Caltech, and failed.

   This is where, in a big lecture hall, you have a long rope with a bowling ball at the end, making a very large pendulum. Stand on one side of the room with the bowling ball touching your nose, drop it, and stand perfectly still as it comes back almost to your nose again, confident that there isn’t enough energy in the system for it to go any higher than it started and whack you.

   I flinched. I couldn’t help it. Rationally, I knew I didn’t need to, but those same instincts that keep me from putting my feet on hot coals kept me from holding my face still with this bigass bowling ball visibly coming in at high speed. The mystic powers one needs are called willpower. And, I guess it’s not mystic, but I’m not sure I have enough of it….

   (I then rationalized later: what if I didn’t drop, but accidentally pushed the ball down a bit, so that it started with some kinetic energy? Then it would wack me. What if I was swaying a bit, and was a little bit forward? What if there was a small earthquake (this was California, after all) that pumped some energy into the system? All of these are rationalizations to try to excuse my flinch, but the real reason was that the instinctive reaction worked faster than my reasoning brain. Better safe than sorry, I guess.)

4. Cynthia on Apr 28th, 2006 at 3:58 pm

   Oh really, physics 101… tell me - if I can easily burn a steak on charcoal, how can coal be a poor conductor of heat? Therefore, if coal is not a great conductor of heat to flesh, then - at the very least - it is a semiconductor of heat to flesh.

5. Clifford on Apr 28th, 2006 at 4:05 pm

   It is our Physics 100 course actually. He’s not standing on the coals, he is walking across them. Also, the charcoal brickettes you are thinking of are denser than the wood-burn coals that people firewalk on. Slightly better conductivity. But the main effect is what I said in the first sentence.

   Try it and see.

   Put another way. When you are next baking some potatoes or a pie, open the oven. Everything in there is at the same really high temperature. You can touch (for a short time) the potatoes and the pie quite comfortably. But you would never touch the metal parts of the overn, right? You already know this. It is because of your instinctive knowledge (from experience) of the different heat conduction capabilities.

   -cvj

6. Clifford on Apr 28th, 2006 at 4:05 pm

   Rob Knop. Yes, the pendulum one is scary.

   -cvj

7. janet on Apr 28th, 2006 at 4:35 pm

   It also helps if you cool down your feet first, with cold water. Judging from the basin in the picture, that’s what he did.

8. damtp_dweller on Apr 28th, 2006 at 4:53 pm

   We used to do the pendulum demonstration with the aid of a stepladder, a clothes iron, and a generous length of rope. Happy days.

9. Clifford on Apr 28th, 2006 at 5:21 pm

   Yes, Janet. The group I did it with years ago actually used a different approach. Use dry feet since it reduces the chance of a piece of coal sticking to your foot and having time to burn. I guess Gene decided to use a different approach. Either way, it helps debunk the mystic nonsense.

   -cvj

10. Rob Knop on Apr 28th, 2006 at 5:22 pm

    But you would never touch the metal parts of the overn, right?

    Unless you’re clumsy. I do this sometimes. I always regret it.

    There’s a similar, analogous demonstration for cool; I think I saw it at the SF Exploratorium first. There are several plates, all at room temperature (which is less than your skin temperature). One is metal, one is wood. The metal one feels much colder… even though they’re all at the same temperature. Same thing, conductivity.

    -Rob

11. Spaceman Spiff on Apr 28th, 2006 at 5:28 pm

    Yes, stepping on to the coals with wet feet means that a whole lot of energy that is conducted to the feet must first go into vaporizing the water on the surface. But even moisture naturally present on and within the skin tissue would serve in this capacity, even before major tissue damage sets in. But exposure time is ultimately of importance - those wood coals are not space shuttle heat tiles…

12. Uncle Al on Apr 28th, 2006 at 5:36 pm

    For shame polluting the atmosphere by burning raw carbon, exacerbating the Greenhouse Effect! You should be burning hydrogen. You should not be breathing, either, or at least not exhaling. Only developing countries deserve to exhale.

    2,2,4-trimethylpentane (isooctane), d = 0.692 g/ml
    2,2,4-trimethylpentane-d18, d = 0.820 g/ml

    We can reduce the price of gasoline to 84 wt-%, $3.20/gallon down to $2.70/gallon, simply by going to perdeuterated fuels. I call this FEMA-nomics. Next year, after intensively funded studies, we substitute C-13 and save some more. Here’s a slogan to rally the masses,

    “Just Add One!”

13. Pražák on Apr 28th, 2006 at 5:59 pm

    Being myself a physicist, I find it funny how physicists react when confronted with a phenomenon of this kind.
    Usually they deny possibility of the phenomenon for years and then, when somebody finds an acceptable explanation, they quickly jump on it and say: see it’s trivial, it’s first grade physics. Usually there is no humble intermediate stage “it exists, but we do not know why”.

    Here in Eastern Europe we were always told by authorities that traditional bulgarian fire dance Nestinarstvo (see e.g. http://library.thinkquest.org/C0130033/d3.html)is some kind of fake. Dancers dance (usually) more than 10 minutes in burning coals, with feets often ankle-deep in the embers. Are you sure that Gene Bickers can do this?

14. The Ridger on Apr 28th, 2006 at 6:48 pm

    Also - are you actually cooking that steak ON the charcoal? Or on a grill over the charcoal - a metal grill that conducts the heat very nicely indeed?

15. steve on Apr 28th, 2006 at 6:57 pm

    We had a very large “monkey gun” to demonstrate the independence of horizontal and vertical motion of a projectile. The device was probably built in the 50s and fired a 100mm diameter (hard) wooden projectile towards a falling bowling ball over a non-trivial distance.

    On the last year the canon was used the projectile struck the bowling ball a bit off center (it was apparently difficult to line up) diverting the projectile towards an overhead projector. The projector lost - badly. Of course the students thought this was wonderful, but the device was retired for safety reasons.

16. Jeff Nuttall on Apr 28th, 2006 at 7:04 pm

    Along not altogether dissimilar lines, I guess: When I was TAing the physics labs at USC, there was one experiment that used liquid nitrogen. Generally, the students would be convinced, from the movies, that liquid nitrogen instantly shattered anything it was poured on, or thereabouts. So…I’d disabuse them of the notion by pouring a generous amount of liquid nitrogen over my hand. This generally got some looks of surprise.

    Oddly, when I mentioned this to some of the other TAs, they were shocked and apparently thought I was risking losing my hands, or something like that. Well, I’ve done that demonstration maybe a couple of dozen times (and actually reached into liquid nitrogen to retrieve things that had sunk inside–though I concede that’s rather more dangerous, and I had to be sure to be quick about it), and both my hands are still in perfect working order…

    Just to be on the safe side, though, every time I did that demonstration I did warn the students not to try it themselves. (It’s not really that dangerous, but there is the risk someone might do something stupid like, say, cupping their hands under the nitrogen, and getting prolonged contact with it…)

    (I’m not sure how happy the lab director would have been to know I was doing this demonstration, but hey, now that I’m no longer working as a TA I can tell about it without fear of reprisals. )

17. Cynthia on Apr 28th, 2006 at 7:28 pm

    The Ridger - I pierce the steak with a wooden stick and then slowly rotate the steak over charcoal heat. The steak cooks quite nicely without the aid of metal conduction.

18. Rob Knop on Apr 28th, 2006 at 7:48 pm

    I’ve never been bold enough to reach into liquid nitrogen, but I’ve watched other people do it. (In grad school, building a spectrometer, we wanted to make sure some parts would still move after thermal contraciton, so we just filled a cooler and plunked them in.)

    I’m a temperature wimp anyway, though. And I’m sure it feels *cold*.

    If you leave your hands in too long, it would be bad… but that’s true of icewater, too.

    I once did suffer from ln2 — poured on the ground, and I was in my socks. And my socks were a wee bit wet. Suddenly, I had ice socks on my feet. That hurt– that was cold.

19. Spaceman Spiff on Apr 28th, 2006 at 10:01 pm

    Cynthia - then you are utilizing radiation and convective energy transfer, rather than conduction. The main energy transfer mode for the “hot coal walker” is conduction.

20. Jeff Nuttall on Apr 29th, 2006 at 3:51 am

    Rob Knop - Actually, the one time I did manage to do some (very mild) harm to myself with the liquid nitrogen demonstration, it was to my feet. I was wearing sandals that day, and when I poured the liquid nitrogen over my hands some got into my sandals and underneath my feet, and there was enough prolonged contact that–well, it didn’t do any permanent damage, but I did get some blisters for a while.

    And yes, reaching into liquid nitrogen definitely does feel cold. (And yeah, of course you can’t leave your hands in for long. Like I said, I had to be sure to to be quick about it.)

21. Cynthia on Apr 29th, 2006 at 7:18 am

    Spaceman - you are right. Thanks for pointing out my error. Unless Gene is levitating off the hot coals, he does not appear to be utilizing radiation and convection heat transfer in his firewalking experiment. Nevertheless, does not maintaining uniform temperature of the hot coals play a role in the overall safety of this walking experiment? I image “hot spots” conducting to the feet might hurt a bit.

22. Clifford on Apr 29th, 2006 at 8:50 am

    Cynthia. The hot spots are irrelevant. It is all one giant hot spot. The temperature is high everywhere. (Temperature and heat should not be confused, by the way.) Nevertheless, the low conductivity means that it cannot transfer heat to you fast enough. Uniformity is irrelevant too….although I imagine it is pretty univform since it has been burning down for at least two hours….. It’s pretty simple, really. Conductivity. That’s it.

    Best,

    -cvj

23. Bob on Apr 29th, 2006 at 9:16 am

    I’m assuming that Cynthia is questioning whether the conductivity, rather than the temperature is uniform throughout the coal cat-walk, in which case it is since I take it that only coal is being used. Another question I have for anyone who has tried this or knows about it, does the conductivity of the coal vary at all throughout the duration of it’s burn cycle?

24. Harv on Apr 29th, 2006 at 10:12 am

    There’s a series of videos made by Jerrol (sp?) Walker on physics which my class watched in high school. I remember one of them being on fire walking (and another on pluging a wet hand into molten lead). He was one of the authors of my intro physics textbook in college (Halliday, Resnick, & Walker) and had an appendix which talked about similar things. He explained that firewalking was often done at night where there would be dew on the grass or that you might get nervous and your feet would sweat. He described in the textbook about his experience firewalking while clutching a physics textbook to his chest.

    As for liquid nitrogen, at Astronomy Camp (www.astronomycamp.org), the prof who runs it does liquid nitrogen demonstrations, including one where campers can “touch Saturn” (liquid nitrogen being about the same temperature as Saturn). He has them open their hands with fingers apart and pointing downward (and no rings on) and pours a little over their hands. No harm done.

    The worst that happened to me with it was a little stayed on my glove while I was filling an instrument dewar at the telescope. I now have a glove with a hole in it.

25. Ponderer of Things on Apr 29th, 2006 at 3:16 pm

    Someone was telling me that sweat on the soles of your feet (if you do NOT dip them in water first) helps too - which is why people who are a little nervous of walking across the coals than those who don’t care.

26. Jeff Nuttall on Apr 29th, 2006 at 3:37 pm

    Regarding the steak issue: There are other factors to consider too. The steak takes a lot longer to cook than just a few minutes. No doubt there is some heat being carried to Dr. Bickers’ feet through convection and radiation while he’s taking steps over the coals, etc., but he’s not spending all that long walking over the coals. Hold a steak over coals for just a minute or two and then withdraw it and it’s not going to be much changed. I’d imagine if Dr. Bickers wandered continuously over hot coals for half an hour, he might find the experience significantly more painful.

    Also, remember that humans, unlike steaks, are alive, and that their systems are actively adapting to the heat. I read an account once (though I don’t have the book with me now where I read it, so I may be misremembering the details) about a certain (apparently rather brave or foolhardy) early researcher who voluntarily spent time in a room heated to a very high temperature, to test human heat tolerance. He brought with him a dog and a steak. I forget exactly how long they spent in there, or what temperature the room was (as I said, I don’t have the book with me, and on what little I remembered I wasn’t able to find anything online with a Google search), but according to the account I read when they left the room the man and the dog were both uncomfortable, but still alive and healthy–but the steak was cooked!

27. slanted tom on May 1st, 2006 at 9:31 am

    Here’s a different kind hot coal that perhaps someone will care to walk across.

    http://www.realityphysics.com/

    I think someone will make it. If not here, where?

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