[Avodah] electronics on shabbat

[Akiva Miller via Avodah]

R' Marty Bluke wrote:

> There is no prohibition to create a light on Shabbat, the
> prohibition is to create a fire or heat metal until it glows.
> It just so happens that until recent times there was no way
> to create light without heat (e.g. incandescent bulbs).

I agree that this ability did not exist until recent times, and that is
exactly why they never asked the question: How do we define fire for
Hilchos Shabbos? Is the glowing metal considered fire because of the heat,
or because of the light, or because of some combination of the two? RMBluke
seems to presume that the heat is the main factor, and the light merely
defines the shiur of heat, but I'd like to see this proven.

By the way, these LED bulbs aren't the only modern way to make light
without heat. We also have the phosphorescent chemicals in a glow stick. Do
such glow sticks constitute "aish"?

According to Rav Moshe Heinemann (of the Star-K; in "Guide to Halachos" by
Nachman Schachter, published by Feldheim, pg 29):

> Activating any electrical device to generate either heat or
> light or increasing the setting on an electrical device to
> generate more heat or light is prohibited because of the
> Melacha D'oraisa of Mav'ir. Examples include intentionally
> 1) activating a heating pad, 2) activating a light, ...

Unfortunately, he does not offer any explanation or sources for his choice
of words "heat OR light". Does anyone know of other poskim who offer
opinions about technologies that make light without heat, or heat without
light?

Akiva Miller
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