Is it posible to heat liquid water to “glowing red hot” (let’s call it 700c)? Presumably it’d have to be under a lot of pressure to keep it liquid. How much pressure? Can we create such conditions on earth which would allow us to see that light?
Doesn’t look like it. See the phase diagram here:
http://www.lsbu.ac.uk/water/phase.html (the last chart is clearest)
Water becomes a super critical fluid above 600 C, which isn’t what we’d typically call a liquid. However, stuff starts to glow around 525C. You can go a bit above that and keep water liquid at about 100 MPA (tough to tell because the pressure scale is logarithmic). I don’t really know much about pressure vessels, but that pressure is pretty easily doable. I’d imagine you’d be able to get a very small clear window into the vessel. It wouldn’t be glowing very much, but you should be able to see something.
What a great site/cite!