[Avodah] electronics on shabbat

[Micha Berger via Avodah]

On Thu, Dec 29, 2016 at 11:50:11PM -0500, Akiva Miller via Avodah wrote:
: In any case, I am curious about what the Raavad means here. Does he mean
: that heating the metal is bishul in *addition* to mav'ir, or does he mean
: that it is bishul and *not* mav'ir?

I think that bishul and mav'ir are mutually exclusive by
definition. Because if they were not, every case of mav'ir that involves
heat -- every case Chazal or rishonim knew of -- would be both. There
is no way to set fire to something without heat causing a change in it.

But in any case, I think the Ra'avad's point in 2:2 is that we see
that putting out the gacheles shel mateches is not mechabeh deOraisa,
and therfore the inverse isn't hav'arah. So yes, I believe he is saying
"and not mav'ir".

: I could go even farther, and suggest that the production of heat without
: light does NOT meet the definition of "aish". My evidence is in the
: halachos of Hatmana, where certain materials do more than merely preserve
: the heat of one's Shabbos food -- they are "mosif hevel", they "add heat".

They do not necessarily generate heat, though. Hatmanah with a hot item
is "mosif hevel" for the food by sharing their heat. Salt is motif hevel
because it dries out meat like roasting does. (Pesachim 76a, Meiri ad loc;
H/T R Yaakov Montrose, Kollel Iyun haDaf.) It is possible that melakh sedomis is
prone to some exothermic reaction when exposed to a common biochemical,
adding heat. But meliach keroseiach has to be true of kashering salt
too.

BTW, hevel is closer to steam than heat. Like the hevel that comes out
of pots that might infiltrate another food in the same enclosed space.

:-)BBii!
-Micha

-- 
Micha Berger             "As long as the candle is still burning,
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