Comment by appplication
14 days ago
> The temperature at the focal point may reach 3,500 °C
I thought this was interesting because it doesn’t really seem like an applicable top level claim, surely this is referring to a specific furnace, not all solar furnaces?
Then this got me thinking if there is some universal upper bound constraint to these temperatures. E.g. if I recall a telescope can’t make a source object brighter than it actually is, and this just seems like a thermal telescope, so I wonder if that principle applies here or not.
> I wonder if that principle applies here or not
It applies, but also in practice the maximum temperature is lower than the theoretical upper bound.
https://what-if.xkcd.com/145/
I'm confident that the physics is correct, but I hate when things are translated for the lay public:
> "In general, there's no way to "overlay" light beams on each other, because the whole system has to be reversible".
Behold, my two torches.
Oh funny, my intuition when I was writing that was “there’s probably an xkcd what if about this”, but I imagined it be about surrounding the sun with mirrors. Same idea though in the end
You may have been thinking of this one instead https://what-if.xkcd.com/141/ . Maybe we should put Randall on the supervillain watchlist.