How would air work on the plane of water?

[some bloke]

Hey everyone!

I'm a keen D&D-er and one of the unexplored regions of the planar map is the elemental plane of water. There's a few handwavey explanations of it, but I want to make it into an entire setting.

As much as one can on an infinite plane of water without a defined gravity field, I want the world to make sense. I have created a logical reason for there to be land within the water, and how it works, but it just struck me that I don't know how bubbles will behave.

The elemental plane of water is an "infinite" span of water which has no surface, and which has no real "depth" - the pressure is as though you were 3ft. below the surface everywhere. I've added a huge disc of coral which forms the main "continent", which slowly turns, bringing regions in and out of warmer and cooler parts of the plane, creating seasons. The plane is dark, as there's no sun, but bioluminescence and magical lights pick up the slack. The "deep" water around the reef is home to leviathans and other horrible monsters - people don't go there.

Now, what happens if air gets in? assuming there were bubbles near the surface of this reef, would they float away from it due to the slight gravitation of the reef and the relative density of water? would it pull toward the reef and stick to it? in either case, what are the limits? It won't float up forever, and it makes no sense for the reef to be inside a bubble, if we went to the extremes.

As I consider it further, with no sun there's no photosynthesis so the bubbles would be rare. I might just make them float freely, clinging to anything that they touch. But still, I would love to hear some more science-y answers for this!

 

[berkeman]

I may regret stepping into this...

As much as one can on an infinite plane of water without a defined gravity field, I want the world to make sense.

A "plane of water" implies a surface.

The elemental plane of water is an "infinite" span of water which has no surface,

Well, which is it young feller? (what movie is that from?)

It seems like you should just deal with the physics of a very large water world with gravity and no sun / some sun or whatever. If you want to apply the laws of physics to your world, you need to avoid making unrealistic assumptions, IMO.

 

[Hornbein]

Good for you coming up with something original. There is still gravity but since the attraction is the same from every direction it cancels out so the net gravity is zero. Pressure would also be the same everywhere, but could be any amount.

Now, what happens if air gets in? assuming there were bubbles near the surface of this reef, would they float away from it due to the slight gravitation of the reef and the relative density of water? would it pull toward the reef and stick to it? in either case, what are the limits? It won't float up forever, and it makes no sense for the reef to be inside a bubble, if we went to the extremes.

You say the reef is denser than the water. If it has the mass of a planet then it will form a sphere with gravity like a planet. Then "up" is away from the surface of the reef.

If the reef is the same density as the water then it won't collapse into a sphere. The gravity of the water surrounding it would cancel out the gravity of the reef, which then could be any shape and any size. No gravity would be felt anywhere.

It also could be dense but not massive enough to collapse. In such a case I would guess the gravity would be not much. Much less than that on the Moon.