In the world that I am making there are hollows all over the planet, which are massive underground subterranean areas of the planet. Think The Hollow of the Gears Of War series. So far the going theory on how they formed was underground rivers, natural cave systems, old volcanic tubes, and things of that nature besides burrowing animals of old.

In order to solve the problem of light and heat my friend and I created Hearthstones, which are Biominerals, that feed on heat, light, and ambient radiation in order to survive. Now the Hearthstones have a feeding and heating phase where they are black and are cold to the touch when absorbing energy, and release light and heat when they aren't. The reason we did this was to make it so that the Hearthstones could keep their environment within a mean of 58 to 72 degrees for ideal environmental conditions to feed. We have talked in depth how this system might work but have run into several roadblocks concerning this. Mainly how it would function and be realistic.

So with this in mind, here are some road blocks my friend and I have run into.

  1. Due to the changes in temperature in the hollows due to the Hearthstones would there be wind currents in them?
  2. Would the presence of summer/ winter affect the hollows, making them opposite to the surface season since the ground would be colder/ warmer in the respective seasons?
  3. Is the system I have suggest feasible or would it need an outside source as well like magma flows or the like?
  • $\begingroup$ What is living in these hollows and what do they eat? If you're planning on having photosythetic plant life down there, your hearthstones are going to need to function differently. $\endgroup$ Oct 31 '19 at 18:48
  • $\begingroup$ Just as a general rule on SE, try to keep to one question per post. Really cool idea tho, I hope my answer helps! $\endgroup$
    – Stephan
    Oct 31 '19 at 19:18
  1. Temperature and Pressure are directly related; meaning: when your Hearthstones radiate energy, they are increasing the pressure of the local atmosphere. If the atmosphere has somewhere of lower pressure to move to (cold areas or open to the surface somewhere) this pressure will propagate to those areas, aka breeze.

  2. Ground temperature is fairly stable below the frost boundary. If these caves are sufficiently deep, odds are there will be no appreciable variance due to the seasons. However, if that's the goal you're looking for, having regular openings, like sinkhole skylights, would allow cold air to flood in during the cold seasons, triggering your Hearthstones' exothermic cycle.

  3. If you want drastic temperature fluctuation from the stones in order to regulate their environment, you'd probably want to have dramatic variance between winter and summer on your planet. As far as massive cave systems: limestone is rather soft and soluble in water. If your planet was formed with some weird geological process that caused massive veins of limestone to form within a harder stone like granite (probably not possible but I'm not a geologist) you could have water erode the caverns over time. As long as you do your research on geology, or stay away from too many specifics, there's nothing particularly far-fetch about your idea.


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