It's just goes on and on and on. There's a bottom when it's practical to have gone that far, because it informs further aspects of the setting, but any further is a bit ridiculous.
I actually had this *exact* issue and had to calculate the price per kilogram of bulk helium-3 fuel to within 1-2 thousand dollars... for the ships in my setting to afford the transits, and required energies for given exhaust velocities to achieve said transits.
And the extraction efficiencies of Helium-3 by mining planes in Saturn's atmosphere, and fractions of helium-3 as an isotope within the atmosphere, extraction rates, price of vehicle operation and net profit per sortie to justify industrial extraction to even support a fusion economy.
“Fantasy authors don’t do research.” An author on reddit built a medieval economy that was so accurate, their protagonist could no longer afford to go on the quest.
How many mining planes would need to be harvesting the atmosphere, how many tons of unprocessed helium-3 they could dredge up per sortie, how many weeks a sortie, the maintenance and parts costs of the reactor components based on reactor topology and style, the cost of fabricating the parts in the first place.
Here's a tiny science detail I doubt anyone will care about, but I think is kinda fun!
The match is usually impregnated with paraffin wax, like candles. As it burns the charred part wicks some of the wax, which the heat of the flame vaporizes and burns just above.
So the flame is just above the charred part of the match, and the part where the wood begins to charr, as the wax evaporates. Without the wax the match would burn in seconds instead of tens of seconds.
Burn one to notice! It's neat.
@feuph3d That, and refrigerant velocity probably helps. Oil vapor’s getting drug around everywhere inside and it’s low volume so the circulation time is short.
A whole home heat pump compressor is quite a bit bigger.