[Avodah] Just How hot is Yad Soledes Bo anyway?

[Micha Berger]

On Mon, Dec 07, 2009 at 07:00:55PM +0000, rabbirichwolpoe at gmail.com wrote:
: Re:  Rn Chana's post
: We weren't measuring YSB directly. We were measuring what is the
: threshold temperature that cooking-bishul takes place. So I see
: retropsectively that I mis-titled the subject line. Sorry for any
: confusion!

I think one of RnCL's points was that it's unclear that yad soledes bo
is linked to actual bishul. As we see from things like keli sheini and
beyond issues, sometimes derekh bishul is a bigger issue than whether
bishul can actually take place.

If that wasn't her intent when writing:
> With all due respect to you chemist colleague's expertise, it seems toe
> that all this is, in terms of the halachic debate, not that relevant.
...
> Proof of this would seem to come in the form of kli sheni and kli hlishi.
> Your chemist friend could no doubt obtain much swifter cooking effects from
> a kli sheni and kli shlishi, but again that does not matter...
then let me put the idea on the table now.

Continuing RnCL's post:
> The one in common use is to point out that the knife used for shchita is
> deemed cold (ie does not need to be treated as though it was cooked by the
> blood of the animal it schechted), even though it is in contact with the
> body temperature of an animal (43 degrees or so, although others have

But for how long? Does the actually knife heat up? (I would think that
if it does, pressure and friction might have more to do with it.)


As for measuring YSB experimentally, R' CO Chait tried this with us when
he was my rebbe in HS. We went down to the lab, took out bunsen burners
and thermometets, divided up into lab partners.

Our answers end up wildly different if you put your hand into hot water
vs if you put your hand into water and slowly heated it up.

(See <http://en.wikipedia.org/wiki/Boiling_frog>, which begins:
    The boiling frog story is a widespread anecdote describing a frog
    slowly being boiled alive. The premise is that if a frog is placed
    in boiling water, it will jump out, but if it is placed in cold
    water that is slowly heated, it will not perceive the danger and
    will be cooked to death. The story is often used as a metaphor for
    the inability of people to react to significant changes that occur
    gradually.[1] According to contemporary biologists the premise
    of the story is not literally true; an actual frog submerged and
    gradually heated will jump out.[2][3] However, 19th century research
    experiments appear to corroborate one underlying premise; that a
    submerged frog will stay still when heated, but only as long as the
    heating is gradual enough.[4]

Lemaaseh, the frog will jump out before dying, but at a far higher temp.
Just like our hands.)

That said, for those who put their finger in at 5 deg intervals rather
than doing it gradually, automatic recoil was in a very narrow range of
temps. I'm not sure what it was. Vague inkling it was 135degF, but don't
put too much stock in that. (Recall, this memory is from the 1979-1980
school year, and its reliability should be assessed based on that.)

My mom, who has been cooking and occasionally burning her hands for
decades, has a much higher tolerance than I do -- never mind than I did
back when my skin was softer.

Tir'u baTov!
-Micha

-- 
Micha Berger             Here is the test to find whether your mission
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