[Avodah] our understanding(s) of fire......change in halacha??

[Joel C. Salomon]

On 09/15/2011 06:04 PM, Harvey Benton wrote:
> our understanding of fire (and its' associated electricity cousin) in
> the minds of the poskim, are not the
> same as they were at the turn of the century when they decided that 
> electricity was assur on shabbas. now our understanding has changed, and
> for instance we know that
> not all fires (eg underwater flares) are the same;

I'm not touching your question about the possibility of change in
halacha, but the halachik definition of fire is interesting.

Consider:  A flame, a glowing coal, and red-hot metal are all considered
"fire".[1]  Is there anything in the way of equating this with
"incandescence"?  Is there anything else halachikly defined as "aish"
that does not fit this, aside from the Chazon Ish's view that all
(most?) electric current qualifies?

[1]  Turning on a glowing-filament light bulb on Shabbos would therefore
be a d'Oraisa [barring discussions of indirect action], no matter what
your view on the halachik status of electricity.