Could This Planet Physically Exist?

Intriguing premise. There may be some choices of solid core diameter and density that make the concept viable. If their explorations reach the water/air or water/space interface, to them that could be mind-blowing.

Don't let science get in the way of a good story. You'll ruin the plot.

Make up your own science to go along with the story line.

Just do like a modern commercial "news" reporter. Don't let the facts get in the way of a good story.

Oh yes, "Destroyer of Worlds" by ... (drum roll please) Larry Niven includes a rapidly advancing society of (somewhat) starfish like creatures with an ability to link minds, that originate "in" a water covered planet, that is roofed over by ice.

Extremely rapidly advancing society, as I recall. That's where the entire rise and fall of the civilization took just a matter of days, wasn't it?

No, that must be something else. I think this is more like steam era to fusion in ten years sort of thing.

Gw'oth

I don't remember how fast the civilization advanced, but they went from zero to sixty (fire to fission) in a few hundred years after breaking through the ice of their world.

Jm'ho, their home world, was a moon circling a gas giant much like Europa and locked in ice.

They were starfish-like creatures and some had the ability to telepathically meld into a 16-creature biological computer. This computing power allowed the species to rapidly advance in technology by avoiding a lot of trial and error.

Breaking through the ice was a real eye opener for them as they had previously no knowledge of anything beyond their own water world.

Perhaps OOBE might want to read Niven's Known Space series and its related books to see for himself.

oh I'm a big fan of Larry Niven. Ringworld is one of the greatest science fiction books ever written. And I have 12 of the 14 Man/Kzin Wars books, about the feline based civilization that is out to destroy mankind in battle. Fascinating stuff. they remind me of Klingons, but even more brutal. I actually own Destroyer of Worlds somewhere in my collection, but I haven't gotten around to reading it yet. Sounds like I should find it and read it.

Not until you leave the liquid will that be a problem.

Could still get the bends...

You need nitrogen gas to have that.

Sea creatures do not really have gas inside their body cavities.

The exceptions are air breathing mammals and swim bladders in fish. The swim bladders are for buoyancy and not that same thing as lungs, but can cause problems if a too rapid ascent is made.

The following is an excellent description of how mammals prevent nitrogen bubbles in the blood. It doesn't apply in the scenario of an ice locked planet, but interesting nonetheless.

Lastly, any lifeforms in a body like Europa likely is not going to use oxygen for cellular respiration and the generation of ATP. The best substitute is sulfur.

A sulfur based metabolism uses sulfur as the agent for reduction and oxygenation in the cell. Oxygenation in chemistry does not mean that oxygen is used as a component, but denotes the transfer of electrons between molecules and is part of generating ATP (Adenosine triphosphate).

Also, such organisms need to remain close to their source of hot sulfur to survive, so wandering away from the sulfur garden is not something that would happen anyway.

No wonder no wander, they would not stand the tremendous unstinkyness.

By weird quirks of circumstance, I have actually participated in editing two best-sellers. I like your idea and encourage you to develop it. Don't spill too many beans, but I hope you keep us posted.

Thanx Tornado! Will do. Sounds like a GA as far as I'm concerned.

There have been other Sci-Fi stories on underwater intelligent life, notable the film "The Abyss," in which the life forms were way ahead of us technologically. Sounds great, but I have difficulty understanding how they could possibly become so. Electronics, electrics, a chemical industry, smelting metals, etc. - underwater? Look at Dolphins - they are supposedly very intelligent, but are not known for their scientific achievements. Would be glad to be proved wrong by your imaginative ideas!

If only dolphins had opposable thumbs!

Now you've really hit on something there. Smelting on a small planet with water as an atmosphere and a shell of ice over it. Talk about a real pollution scenario. The planet could be slowly dying from pollution.

500 miles of ocean has some serious crushing power. your fantasy population has interesting lung capacities

Lung capacity? No, no, no - I think we need to be envisioning something with gills. Some of those fish from the depths of the trench in the Pacific with the built in lights would be very interesting.

Lungs/Gills? Where is the oxygen coming from?

On Earth I think sea water gets its dissolved oxygen from the surface air and surface plants (or those close enough to the surface to receive sunlight)?

Where would oxygen come from on an ice locked world with no photosynthesis?

Point taken - so we're talking anaerobic creatures. (???)

I think so if the original premise is that the world is ice covered, like Europe.

We already have evidence of both sulfur based and arsenic based metabolic processes on Earth, so life could technically exist under the right conditions on a moon/planet like Europe as long as there is a long term source of energy (i.e., heat from tidal kneading) and organics to sustain the chemistry.

No ice

There's no ice covering this planet.

Some of you keep ignoring that point I keep making about my planet. this isn't Europa. it's not covered with ice.. The water goes all the way to the surface

Okay - just who is writing this story?

Oh.....I guess you are - sorry. Never should have mentioned Europa - just confused us.

Okay. That would demand an atmosphere and sufficient gravity to retain it.

That can change the dynamics of the whole ecosystem. You will need large quantities of kelp or other sea vegetation to provide enough oxygen for sea and air.

I would still seek someone that is an exobiologist to get a handle on what the ground rules would be like if you want to make such a world scientifically reasonable. Keeping the story plausible at least helps to create a minimum level of suspension of disbelief required to keep readers from abandoning the book.

However, I have always contended that good literature has less to do with the setting as it does with the struggle and drama of the human spirit (even if that spirit isn't human you still need to couch it as such).

So, this planet is in the Goldilocks's zone in an orbit that is stable and nearly circular so the seasons are mild. There would need to be a decent magnetic field generated by the core to protect any atmosphere from being swept away by solar activity.

To have a stable orbit, it would help to have a moon, which would then cause tides of what ever magnitude you like. With water and an atmosphere, you would have storms and huricanes with tornados. You might also have some life forms that have evolved to live on the surface. All plant life would probably float on the surface unless there was some other life form that lived on volcanic activity really deep.

I can't imagine how some species would be able to leave the water in this scenerio except for something like flying fish. Might there be some huge volcano that creates just a little bit of land? It would be like Atlantis on thin straw.

Europa is unique is that the moon is under constant tidal kneading from Jupiter.

The internal friction causes the interior of the moon to get very hot. This is what keeps a liquid "water" layer above the solid core. The ice is the boundary between the vacuum of space and that liquid layer.

You can see large cracks in the ice from expansion and cooling from tidal forces. As liquid bubbles through the cracks it evaporates and freezes at the same time, healing the cracks.

As for life, you need a power source to sustain it. No light will reach the liquid layer, so you must have another source.

On Earth that has been shown to been sulfur eruptions from vents in the seabed floor. The sulfur (and arsenic). The heat from these vents is intense, but life has proved resilient and adaptable to those conditions and no oxygen or light is required.

The bad news is that such life would never develop eyes and the the prospect of more complex life forms is slim to none under that biochemistry. Additionally, you are limited to the area around the vent for sustaining the environment to live.

So the likelihood of developing intelligent life is next to impossible due to the biological limitations that sulfur or arsenic chemistries provide and without light you have no eyes (and no sky), which limits a key sense for intellectual and technological advancement (assuming the biological chemistry problems were ignored).

Now a planet like Europa would soon freeze solid in an independent orbit since there are no longer the strong tidal forces to keep the core active and hot that Jupiter provides. That's another stroke against the story, unfortunately.

Lastly, any prospect for a technological form of life must have resources to produce metal and other synthesized materials. Building advanced machinery and in particular, electronics, requires an atmosphere, which is a hostile environment for aquatic life (amphibious life excepted).

I believe not only tital pressure from Jupiter, but it's also effected by radiation from Jupiter.

Radiation would only affect the outside of the moon. Remember, water is an excellent shield for radiation.

Second, the surface would take the brunt of the heating and that remains as ice, so Jupiter's radiation probably does not account for much thermal activity on Europa, clearly not enough to form a deep liquid layer trapped under deep ice as proposed.

His planet could be heated the same way Europa is, by tidal friction. Eyes would not be necessary, sonar works just fine. Agreed, their technology is likely to be low tech.

A few ideas:

The light source could be a radioactive asteroid that struck the planet 50 million years in the past, providing light and triggering the development of sight and intelligence.

You'll need an alien with a least a touch of humanity, like in the movie 'Avatar'. Your readers need to be able to see themselves as one of the aliens on this planet.

You need an event to trigger the action of the story. For example, the planet undergoes some unusual celestial mechanics where every 10,000 years it reaches a perihelion dangerously close to its parent star causing the oceans to begin to boil.

It depends on the gravitational pull of the rocky core that all will settle. Definitely at the surface of water and space, water molecules will evaporize due to the vacuum, without the sun or heat, the evaporation will consequently settles as ice covering the surface until equilibrium state is attained. Ice as a good thermal insulator and solid covering at the surface for the space vacuum, I imagine life beneath could exist only if there be energy available at the rocky core. It could be a radioactive core at the center or one that is influenced by electromagnetic effect by external planets or stars nearby. Next, it could be a biochemical reaction dependent life then originating at the core. If there be intelligent life, their socio-political interest and development solely is to go to the source and would probably has no idea and intentions to go to the outside world. Lifeforms will have solely developed thermal sensing organs where optical sensing is not necessary therefore this will limit their exploration capability on the outside world given the icy surface. Definitely no stargazing, no further imagination-a just cause for exploration and investigation. This would be the limiting factor for their intelligence and intelligent life as we imagine is less probable on this planet.

Funny though their life would be like that of living inside the box. opposite on your Out of the Box experience, just kidding

Unique bioluminescent micro and macro organisms inhabit the water. Lots of light at all depths.

Low gravity alleviates much of the pressure issues as well otherwise all gases produced would stay in a supercritical fluid state.

This would allow for fabrication of higher tech items to be done is special vapor chambers similar to what we have for vacuum chambers of which can be quite large.

Another stroke against the idea of developing intelligence is that on Earth we have a very diverse biosphere. This is not likely the case on Europa (if it has one at all).

I think the environment that best suits the development of intelligence is one of great diversity, which acts as an advanced lab to experiment wit a large variety of solutions to environmental problems and survival.

On Earth that process took billions of years to yield the creatures we see today.

That poses two issues for Europa.

First, is a diverse environment for a biosphere. That may be a challenge for a world devoid of sunlight and only one source of energy (heat). It's hard to tell just how diverse the undersea world of Europa is, but it is surly less diverse than Earth.

Second, Europe needs a long period of geological stability. That means that the heating and environment must be maintained within certain limits over a long time to allow for life to develop and diverge into higher organized creatures and eventually intelligence. There definitely needs to be changes in the environment (this is what spawns evolution), but it can't change too much nor too fast.

I still think that intelligence is a part of the process of evolution of life and is a direct response to the environmental challenges that life must exist in.

In other words, if the system such as Europa only has a limited set of challenges for survival, any spawning of life will probably hit some steady-state in the development process and remained locked at that level of development. There simply is nothing to drive further change as the organisms already have little threat to their survival. Sort of an evolutional dead end.

ok will turn a negative into a positive. Will find a way to give the planet environmental diversity. You're right I think that's needed

GA

I would relax the requirement that your species lives on the surface of the rocky core. There is nothing magical about living on rocky cores. For minerals? They can extract them from the water. The technique they use for this does not necessarily have to be a technology - it could be a byproduct of their metabolism. For example, horsetails (plants) naturally exude silicon carbide crystals at their buds. Early pioneers of the US west used horsetails to scrub their pots and pans. Silicon carbide is extremely hard but was/is also used in fabricating blue LEDs - your species' lighting technology may take advantage of this property. Eucalyptus trees in Australia concentrate gold in their leaves - about as close as you can get to money growing on trees. And we all know about mollusks which exude calcium carbonate to produce their shells. Your creatures? They could secrete metallic iron, or magnesium, some highly valuable (to us) alloys or whatever you/they need to develop their craft or whatever you've planned for their society's technological development.

Forget the rocky core. Water under extreme pressure forms dense ices even at high temperatures and so they would not have access to their planet's core and may not wish to, anyway, because of the high temperatures (if the planet is subject to tidal forces from a nearby star or large planet, like Jupiter). They may not even need to live on the surface of the icy wrapper but could be fully aquatic, like certain deep-sea fishes. The page is still blank, so it's up to you how the story goes. Glad you're trying to keep it plausible.

thank you Europium. you made some good suggestions there. But I don't want this civilization to be swimmers. I don't want them to be aware of the surface of the ocean. That's kind of a major plot point. the liquid needs to be their "universe", with no known end to it (to their knowledge). I'm trying to keep analogy between them in the liquid, and us regarding space and the universe. Because the eventual discovery that there is in fact an end to the liquid its going to be a big deal and part of the climax. So I need to keep them down down low. And their journey of exploration of the depths above is a major part of the story.

and yes, I'm trying to keep it plausible within reason. At least to the extent where floating mountains and thinking trees are plausible on Avatar.

Your swimmers don't necessarily have to approach the surface. They could have evolved in a temperate 'Goldilocks Zone' somewhere between the core and the surface. Too close to the core and it's too hot or it's impenetrable ice (or both) and too near the surface (of which they're yet unawares) and it's too bluddy cold. Europa's surface is not just ice, right at the surface it's ice that's never rises above minus 260 degrees Fahrenheit (minus 160 degrees Celsius). What species would like to venture there without a damn good reason?

Nor do you need 500 miles of water depth to make the surface unobservable. In Earth's oceans you scarcely need to dive below 100 metres before it's too faint to see the surface. Fifty miles deep? That water could be as clear as Bonito, Mato Grosso do Sul in Brazil, but fifty miles of it would be as opaque as flint.

I like the Goldilocks zone. But remember I have a second civilization living on the surface, and I'm trying to avoid the ocean being covered in ice.

I'm still liking the floating continents idea. I could do a lot with that. Including artifacts and debris that comes from these floating continents and are a mystery to the bottom dwellers as they sink to the bottom. they may even use this rain of debris as some kind of building materials or something useful

Maybe the rain of debris is their food. Lots of species at the bottom of Earth's oceans subsist on the rain of debris from organisms farther up.

They're called 'lawyers.'

Something else you may wish to consider is your species energy source to power their civilisation. One novel approach (no pun intended) might be an induced current thanks to a parent planet's enormous magnetic field - like Jupiter's. (if it were possible to see Jupiter's magnetosphere, from Earth it would appear larger than a full moon. Jupiter's magnetic field is enormous).

Given that your world consists largely of liquid water (at least to some reasonable depth below the surface beyond which it turns to ice), and given that oceans tend to contain a significant mineral content, rendering the water highly electrically conductive, such a large electrical conductor moving through a parent planet's magnetic field would induce large electrical currents in your satellite's liquid wrapper. Your species could harvest this energy using vast vertical metallic grids, for example. Advanced technological societies consume large amounts of energy and thermal vents just won't cut it. They'll need something more and more reliable.

very i nteresting. I may go in that direction. I'll wait to see what other comments there are on that idea.

another decision I need to make is whether Voda is a planet unto itself, or if it is a moon of another planet which may or may not have certain characteristics that influence Voda in some way that is beneficial to our two civilizations in some way

Your decision should be based on whatever outcome you want as a result. Making your world a satellite of another raises abundant possibilities, such as the one I mentioned above.

Caveat: do not make your world a satellite of a magnetar - a collapsed star having an astronomically huge magnetic field. Why? Magnetars persist as magnetars for only about 10,000 years, a mere wink of an eye in cosmological terms, giving your civilisation little time to evolve a technology dependant on that. You could, of course, and take advantage of an impending energy crisis as the magnetar spins down (your creatures don't know why their grid is losing power, for instance, but without their having to know anything about what's beyond their immediate surroundings), but there other problems: the environment around such a star is hostile in the extreme. Radiation from accelerated charged particles would pelt the planet incessantly, making it inhospitable to life.

If it were my story? I would make my world a satellite of another, a gas giant like Jupiter. Plus, it's plausible. Many if not most of the exoplanets thus far discovered are enormous gas giants (it's why they were so easy to discover).

Good ideas! Bioluminescence and caverns. I think I can work with that.

GA

We really don't know what is out there. I kind of like the idea of pair of planets ending up circling each other but in orbit around a normal star. Eventually those planets are going to merge. And that would eventually become an exteninction event with little chance of any bioligical life form, other than bactereia perhaps, to survive.

Of course, you could just have the sun start to show signs of becoming a red giant. That would be motivation to migrate to the stars.

The Earth/Moon system is such a binary planet. The Moon is not a satellite of Earth but of the Sun. How can you tell? From the Sun's POV, the Moon's orbit is everywhere convex.

Such planets do not merge; rather, they drift apart, thanks to energy lost through tidal friction (not just sea tides in the case of Earth, there are land-tides also). This is true of the Earth/Moon system as well; the Earth and the Moon are drifting apart a few cm per year. The Earth's rotation rate is also slowing down. The drifting apart will continue until both planets' diurnal periods are synchronised to their orbital periods. This synchronisation is already true of the Moon; one side of the Moon always faces Earth (but it does nutate a bit, and so we can see a few percent more than one-half of the Moon's face as it goes back and forth from Earth's POV). Earth will one day follow suit but is taking longer because of its larger angular momentum.

I doubt if lifeforms will mimic light in the absence of it, if all source depends on the heat of the core ever since the beginning.

Lifeforms at the depth of the sea here on Earth mimic light for predation because in the first place that's the source abundant is provided by the sun and all is attracted to it.

There will also be issue on the hierarchy/niches of lifeforms with respect to depth. Diversity will flourished on the lowest part where source is abundant, material or energy transport will be a reverse to what is here on Earth. Usually, lifeforms here on Earth survive on deep ocean by scavenging dead carcass at the surface since by gravity all will settle in the bottom of the sea. As to this planet it will be an issue. What lifeforms could exist at upper level of the sea and how would they survive?--nonetheless if and only if they will scavenge fart from organism or bubbles of gases from the core--that's crazy stuff but probable.

"I doubt if lifeforms will mimic light in the absence of it,"

But life on Earth here developed intelligence despite its initial absence.

Light and the EM spectrum in general are a very persistent effect in the universe of which plays a moderate role in the actions and reactions of molecular events. Developing sight or at least a primary sense that takes advantage of the spectrum we see or can not see seems like a logical adaptation to me.

They may not see all of the light spectrum we see but that does not exclude the evolution of the ability to see at a different spectrum range that works for them.

I might not be intelligent but I mimic it damn well!

The whole driver here is survival. If eyes in a dark world are an advantage, then after some length of time it is possible that they may develop.

On Earth many deep sea fish have some sort of optical sensory, even when they dwell exclusively below the photic zone of the sea where no light is available.

And there examples of bioluminescence in deep sea life, too.

One thing that probably would be a real hurtle for intelligent life at such pressures is that the fluidity of cell membranes decreases, which reduces metabolic efficiency, which makes it much more difficult to sustain larger brains required for intelligence since they require a large degree of metabolic function.

In humans we have already pretty much reached the brain size limit due to our body size and its ability to supply both nutrient, carbon waste scrubbing, and oxygen needs.

This is a fascinating subject, but the original poster might do well to befriend an exobiologist if they would like to have some form of grounded science to build from on the water world planet.

Oh yeah, who knows really what possibilities could there be. As long as it falls in the realm of physics and thermodynamics down there, it's far more than we could imagine.

Anything goes damn well with a glass of beer (even fiction).

Plenty of great comments! Thank you for your interest and suggestions. Let me point out a few more details of my water world. This world is not Europa, but only similar in certain aspects. The differences are as follows:

There is no ice layer covering the water.this planet is in its own Goldilocks zone, relative to its sun.

I like the bioluminescence as a light source. This could either be something floating around in the water (theIr "sky"), or it could be planet bound In their floor. I do believe eyesight is necessary For our inhabitants

the intelligent life is not free floating and swimming like fish with bladders, but rather gravitationally bound to the central rocky core. Although, their wildlife does include fish flying in their sky. But a powered vehicle of some sort is required to leave the surface of the core and delve into the watery Heights.

Dry caverns are a good idea, sort of the negative equivalent of our lakes on earth. Although the life forms breathe in the water, over time they have developed the technology to explore and work in these waterless expenses or caverns, much as we have developed the ability to work in and explore underwater. These dry areas would allow technologies to be developed That couldn't be developed within the water itself. Additionally these dry pockets may have their own lower life forms developing within them. This would allow biodiversity.

the next question is should this B an actual planet, or a moon? Would it being a moon with all the additional Astro mechanics involved, give it some advantages for diversity and 4 intelligent life developing?

My world is becoming more defined.

pardon my odd typos. I'm talk texting into my phone, and large fingers and small text makes editing the typos somewhat challenging.

Just hope you are not driving, too! :-}

well actually I'm driving a bus full of old ladies to a prayer meetin'. But no worries. Its all good

That good deed pays for all your ills. :-)

Hmmm...

That sounds like a real out of box experience in and of itself!

Henceforth, my water planet shall be called Voda :)

Sounds like great fun. But to add science to the mix? why?

Been done by SpongeBob but nice try.

There is no frozen shell covering my planet. this is not Europa. The water goes all the way to the surface. It is in a warmer part of its solar system.

it's not covered with ice

a colony of blind land dwellers? How does that have anything to do at all with my story line of a civilization 500 miles below the surface of water? You do realize we're developing a science fiction story and not a scientific thesis of biology under pressure, right?there are famous and successful stories written of time travel and alternate dimensions that still fall under the category of science fiction and are accepted as plausible. My story line is no more impossible than any of those. It's impossible for technology 2 develop under such pressures? We certainly don't know that.. I'm asking our CR4 family for advice on how to make my story line plausible within the realm of science fiction. not for reasons why it's a dumb idea and to change the entire plot.

but thanks for your comments anyways. Its all good.

"I'm asking our CR4 family for advice on how to make my story line plausible within the realm of science fiction."

I think that is what most people are trying to do. You just don't like some of the answers.

Well, welcome to the world of science, where someone postulates something and the rest of the world tries to poke holes in it.

If you are trying create a "plausible" scenario it only figures that you need to understand both the enablers and the inhibitors of your proposed science. In what way does a 500 mile deep ocean limit technology?

But it all depends on your definition of "plausible". If you want to say that all things are possible, then I guess your question doesn't matter.

As for the colony of the blind goes, whats the difference between a blind civilization and a civilization trapped in a world of darkness?

Lastly, don't loose sight (no pun intended) of the purpose of your book. Are you trying to just get your name known, fortune, is there a deeper message, or are you just after a personal adventure and having fun writing a story?

I Did say that I appreciate your comments, as all comments are useful in one way or other. But you are saying that things are impossible that clearly are not impossible, only improbable according to the science that we are aware of... and particularly within the scope of what qualifies as science fiction. The things you are saying are impossible are totally eliminating my entire plot line. The main plot that I presented was not people who live in darkness, as we've already discussed bioluminescence and other technologies the civilization has. The main plot of the story is people who have liquid as their universe, as opposed to air and space. And they don't know that they live on a planet of water because they have never been able to reach the surface.

by starting this thread I was hoping to gather suggestions on how to move forward with my main plot and yet still remain within what is scientifically plausible. but simply shooting down everything that I propose as being impossible isn't advancing the purpose for which I asked original question.

So let's keep the conversation light and positive. I'm just trying to get people's imaginations flowing, if they wish to contribute, and have fun with this. Not simply find reasons why this would never work.

But anyway, you are a knowledgeable person and I appreciate your input. You brought up some good points. But I still think its fun to try to find ways for my premise TO work, and not only reasons why it could never work.

Yes, but you asked, "Could This Planet Physically Exist?"

While the planet could exist, there are serious technological barriers that need to be addressed.

I never really said the word impossible, but I did stress that the likelihood of some scenarios may not be "plausible" for your story.

Secondly, you didn't state what you thought I said was impossible, so I can't really comment on anything specific.

Lastly, the blindness I was talking about is not so much to do with being aware of one's immediate surroundings as being unaware of what lies beyond.

A blind person's world is much different than the world where one has sight of the sky and the stars (assuming the former never had sight from the beginning). Essentially, you are creating a world optically and electromagnetically shielded from the rest of the universe. The same drama applies to both a blind community and your virtual world and they face the exact same challenges with discovering things they could neither see nor imagine.

So, whether or not you intended it, you are creating a story of a community who live in darkness, estranged from the rest of the universe.

You say that the main plot is about a liquid environment, but it really sounds like the real drama of the story line is about the struggle with their own ignorance induced by the world they live in. To me that would seem to be the more intriguing component of the story.

yes, as I said, the pressure issues are a challenge. That's why they have developed some technology but are still confined to the seabed. It is in parallel to the vacuum issues that mankind experienced during our early space program. That is one of the major storylines.

as far as life not being able to develop under such astronomically high pressures,it is not out of the realm of possibility, and there's no more far fetched then many of the great science fiction stories that speak of life as we do not know it. it can be far-fetched yet still plausible, and still be based on sound scientific principles. 50 years ago, who knew that organisms could thrive in an acid, or in the high heat near volcanic vents?Extrapolating the plausible is the basis of science fiction

What keeps the water surface from evaporating? How can a dry cavern exist? What dryness is it filled with? Have you calculated the pressure under 500 miles of water? What sort of thermal gradients will you have? The temperature and pressure my well be such that there is no distinction between water and steam, and biological processes would require great imagination. If, on the other hand, the rocky surface has a temperature which does not cook life, then, 500 miles above, assuming a sort of adiabatic lapse rate, it will very cold and icy. Yes, water is supposedly incompressible, but not absolutely and surely there will be some sort of convection, especially if the rocky core is a heat source. If the intelligent beings are not fish but "walk" on the surface of the core, what sort of material culture can they have? What raw materials can they use to create a probe or whatever? For that matter, what will they eat? Consider: even if dolphins had opposable thumbs, what could they do with them? Weave seaweed fish nets?

LOL, that rocks!

I can use some of that. I wonder... Perhaps the secondary plot would be the fact that there are two civilizations, who have no idea of the existence of each other. 1 grounded on the seafloor, and the other existing on floating islands of some sort. and the story is about the journey of the two peoples discovering each other. I think I would want the underwater group to be the more advanced of the two

Thanks. It was fun thinking about it.

Technical question for the experts: Waves tend to be generated by wind. Would a kelp forest that it not anchored to the sea floor reduce the effect of wind, keeping the size of waves low? Otherwise you could have enormous wind-generated waves that just kept going, and going, and going.

Might a kelp forest have any dampening effect on a tsunami generated by tectonics or meteor strikes?

Kelp will help inhibit waves.

However, a tsunami does not generate waves in the open sea. The only way you get a wave from a tsunami is when the tsunami strikes the shoreline. The rising shoreline at the coast first causes the water to recede followed by the actual wave.

You could be on a boat in the middle of the ocean and a tsunami could pass you by and you would not notice it.

Surface waves would probably be pretty homogeneous and weak over much of the globe as there would be no real wind circulation in the atmosphere.

Without landmass there is no real atmospheric solar temperature differences except between day and night and the water will mitigate that.

Without the surface temperature gradients there will be no real vertical thermals and downdrafts. Weather patterns will be pretty much the same everywhere you go, except maybe the polar regions.

Thanks. I thought the kelp would have to have some effect.

In regard to the polar regions, I thought that Earth's trade winds were generated by temperature differences between the equator and the poles, and shifted spinward or antospinward by coriolis forces.

Yes, but I think landmass plays a significant roll in all of this, which is going to be absent in a total water world.

It would be really neat if there was some way to software model such a planet to see how it would all work. I have no idea what institutions would have such software/computers available to do it, but it would be neat.

I'm going to quibble a little bit with your answer. You're right that you won't notice a tsunami on the open sea, but they are still waves. They only turn into BREAKING waves when the water gets shallow. Is that what you meant?

Seems to me that depending on the cause of a tsunami you could have violent wave action at the origin. A big meteor will cause a big splash, then a tsunami afterward.

My understanding is at open sea the wavelength is so long it only appears as a slow vertical displacement, as if a tide was at work. Much different than a breaking wave as you point out.

That wavelength period could be minutes or longer, so it is not going to be easy to recognize on open seas where there are no other references to observe such a slow change.

Yes, an impact into the ocean or a nuclear blast would produce a breaking wave, but a deep sea earthquake (the more common source) would not.

Agreed.

Nice analysis.

Good point. I forgot about Ice Vi.

Okay, maybe the ocean is not as deep.

Maybe the gravity is lower, with a much smaller iron core, so that the pressure gradient is much lower. The planet doesn't have to hold onto its atmosphere as long as Earth does, only long enough to develop life. Maybe for a much shorter time than Mars did.

Also, maybe the ocean is not water. It could be methane or other hydrocarbons. There could be a process that reduces methane to higher chain hydrocarbon like oil. Could even be a biological process. After all, biological processes created all the oxygen in the atmosphere here.

The author stated no ice on Voda, so you need an atmosphere or the water will evaporate into space, which means a reasonable gravity to retain that atmosphere and most likely a magnetic field.

There are two other factors. As you go down into a planet, the gravity decreases. So the pressure will rise more and more slowly as you descend. That increases the depth at which the Ice VI forms.

The other factor is that very large, not very dense planets have enormous gravitational fields, but out near the surface the gravity is not very strong. Gravity at the surface of Saturn is less than Earth's. The gravity at the surface of Jupiter is 2.5 that of Earth.

If the inhabitants of the planet live on the "bottom" of the ocean, that is simply the point at which water becomes Ice VI. Can you calculate how deep that is? They don't really have to live on a rocky bottom. The can live on the Ice VI bottom.

Underwater igloos. :-)

Actually, I don't think that pressure will begin to decrease with depth.

If we have a planet with enough mass to retain an atmosphere, 500 miles down is not all that significant compared to the total diameter of such a planet.

I didn't say pressure would decrease with depth. I said it would rise more and more slowly as you descend.

Gravity decreases with depth, until it is zero at the very center of the planet. Pressure increases but levels off and and approaches an asymptote.

Imagine a planet 10,000 miles in diameter with a sea 500 miles deep.

The sea bed is only 10% of the total radius of the planet in this case and the change in gravity is not going to be substantial. It will be lower, but I really don't have time to do all the math to calculate how much.

Zero G is still another 4,500 miles down past the sea bed.

10,000 miles diameter is only about 25% larger than the Earth's diameter and so the surface gravity would be about 50% greater (all else being more or less equal). Give it Earth's diameter and you could still have an ocean 500 miles deep.

Agreed. Considering that the core will be much denser than the ocean, the change in gravity is still less significant for those circumstances. But it does still lower the depth of the Ice VI transition a little.

It can't make too much of a difference in that because "If you look to the water phase diagram...you will see that at 300°K water turns into ice VI at less than 10kbar (less than 100km)", which is about 60 miles down from sea level, according to Alex's calculations in post #70.

If true, then it really doesn't matter what the gravity is as you hit the seabed because the threshold for ice is about 440 miles above the seabed floor.

That will be true on Earth. I was thinking about either a smaller planet with a deep ocean and a small core, even if it loses its atmosphere to space, or a much larger planet like a gas giant.

Saturn is not very dense at all; less dense than water. If you had a tub of water big enough, Saturn would float in it.

I'm trying to imagine what would happen to Saturn if you put it into a big tub of water. I kind of doubt it would involve floating. Maybe more of a big hydrogen mess. With a diamond at the bottom. (Big, big, diamond.)

Given that the whole idea of *putting* Saturn anywhere is speculative at best, putting it in a tub of water is clearly a gedanken experiment and should be taken as such. Someday, maybe, if we ever reach Type II or III Civilisation status, we might give it a try but first, we need to concentrate our efforts on surviving our current Type Zero status. De Beers can launch an expedition later.

Hm. The idea of NOT taking is as a gendanken experiment is an interesting thought.

I'm imagining a big (very big) washtub of water sitting out by Saturn, with some unknown source of gravity keeping the water inside without pulling the washtub and Saturn together into a black hole somewhere, and my grandmother getting ready to plunk Saturn into the tub like a baby to get rid of those dirty rings and moons, and then popping it back into orbit without it dissolving into the water.

But if she did do it, she would probably have to throw out the baby with the bathwater.

very interesting developments for my planet today! Alex Roman, excellent post. Thank you. You are exactly that kind of person I was hoping what come upon this thread. That's very good information.

so between you, hero, and canary...my planet is beginning to be a little more realistic. Good stuff! The main points that I'm trying to hold intact, are that there are two civilizations separated by the depths of the liquid that covers the planet. it doesn't have to be water. The planet doesn't have to be the size of Mars. The depths of the lower civilization does not need to be 500 miles. Just deep enough that they have never seen or been aware of the surface above.

I think that the floating islands are a good idea. These islands could be massive, perhaps even continent size. Very thick, just not connected to the bottom. This could make for some interesting continental drift situations. Where the continents shift and slowly collide, and then eventually perhaps even bounce off of each other. Like a planet wide game of slow motion pinball. Perhaps the debris falling from above would be the equivalent of meteorites to the civilization below. With unexplained origins as far as they are concerned.

and yes, the bottom dwellers could live on the ice at the bottom of the ocean, but that would eliminate Their ability 2 mine for metals and advanced the technology and civilization. I'll need to find a way around that.