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Re: [Phys-l] tiny bubbles

How's this: the sky is blu, for the same reason * there are nucleation sites, admittedly very small.
* no liquid has uniform density (except a Bose condensate?)


Stefan Jeglinski wrote: [back in Feb.]

Ionizing rays, entering the vessel would play a role. But your ideal
world probably does not have such rays.

Fair enough. To be more clear, I'm trying to figure if the ultimate
"force" in this matter is still nucleation sites. Or does something
else substitute for such sites? An argument that uneven heating could
create density gradients that in effect were equivalent to a
nucleation site, seems plausible. Or your ionizing rays creating
highly localized conditions that are essentially... nucleation sites?

Bill Beaty's page (referenced in another post) dodged the most
important question, when he said "since its temperature has risen so
high above 100C that bubbles are appearing spontaneously". OK, what's
causing the bubbles to appear *spontaneously*? Is it merely a
smaller-scale nucleation site such as a microscopic steam bubble? If
so, how does said steam bubble occur? As a result of even smaller
nucleation sites?

Perhaps on any scale, one can observe *something* that can be
considered a nucleation site. I have no problem with that - I'm just
curious to know if eventually there is a departure from this
mechanism, or if it's nucleation sites all the way down, as it were.

I quite suspect reality keeps this from being answered experimentally
without great difficulty. I think I once ran across
discussion/publication of the highest temperatures ever achieved,
after careful preparation, for superheated water, but I don't recall
the result.

Stefan Jeglinski