That seems like a very landbased mindset. From a high level, what is an ocean but a thick atmosphere? I could even imagine an underwater culture would be quicker to explore because they would surely discover the surface of the ocean quicker than we discovered the concept of the atmosphere and that innately leads to the questions of whether the atmosphere has a "surface" and what is above it.

There is also the issue that they will likely never discover fire and thus chemistry and metallurgy.

This still seems to be based on assumptions coming from our own history and situation. I don't know why some hypothetical species needs fire for chemistry or even metallurgy for that matter or why an underwater civilization couldn't eventually discover fire themselves. There is also the potential that our reliance on combustion based rocketry is actually a crutch preventing us further space exploration considering how impractical it seems for interstellar travel.

Chemistry and reactions would absolutely still be a thing. Reactions happen underwater all the time such as the complex decay of organic matter.

The fire meta get's postponed until trapping air inside bags happens (could be seaweed/skin based bags).

Then you need to make a habit of collecting a bunch of air and trapping it and then can begin exploring chemical reactions in the air.

ex: take dead but not decomposed organic matter, dry it out in hot air bag (maybe cover the bag in black squid ink and float the bag of air in the ocean out in the sun's rays for day to warm it up.

Then eventually you need to have the insight to do friction based experiments in the bag with dried materials and then one discovers fire in a massive breakthrough not dissimilar to when humans created Bose Einstein Condensates for the first time in highly specialized environments.

Nothing here says "impossible" to me. I bet if whales had fingers to easily manipulate matter they might've already done all this by now.

While I agree that there is no logical reason that underwater organisms could not become highly intelligent or advance to the level of doing experiments with fire, it is clear that being underwater is an additional barrier.

As such, the number of intelligent underwater civilizations, that could get near our present level of advancement, would likely be significantly lower. Not impossible (because of how large the universe is), but some order of magnitude, less possible.

> While I agree that there is no logical reason that underwater organisms could not become highly intelligent or advance to the level of doing experiments with fire, it is clear that being underwater is an additional barrier.

Meanwhile, a few thousand lightyears away, some sort of talking crab is rubbishing the idea that industrial civilisation could arise on land; after all, they wouldn't even have access to hydrothermal vents! What would they do for energy, burn plants?

(I really think we're inclined to build a _lot_ of unwarranted assumptions into what industrial civilisation has to look like and how you have to get there, because it's what we did.)

> As such, the number of intelligent underwater civilizations, that could get near our present level of advancement, would likely be significantly lower.

Unless of course, having opposable thumbs and >50 year lifespan and intelligence in the water causes you to go through a completely different developmental path than land based creatures. We just don't know.

Why so complicated? There could be many 'mini-labs' in underwater caves, accidental discovery of inverse diving bell so to speak. With trapped gases of any sort, by whichever process(volcanism?) pushing the water out downwards, while unable to escape upwards. Ready to explore, and mess around with. Maybe even in something like free floating coral reefs. Or below the ice.

Why is fire the only chemical pathway to metallurgy?

Can they not discover fire in underwater caves?

Can they not build underwater containers that hold the necessary materials to do chemistry, similar to what we do with bioreactors, flasks, beakers, and pressure vessels?

They could roll nodules near black smokers, and have fun with methane hydrates instead?

Also electricity be experiencing shocks from electric eels, or similar. Economic lighting by bioluminescence.

To support this: Oceans are more conducive to exploration due to their natural currents and lack of mountainous regions or rivers which inhibit movement.

Like the comment below was getting at: if you are water bound, you are very unlikely to discover or become proficient with fire, which to us, as if now seems like a requirement to travel through space.

There’s also the massive weight disadvantage water has compared to “air”.

So no fire and have to travel with a water filled rocket instead.

But again maybe these are just land centered views.

Maybe you can just inject oxygen into the water that merely surrounds your head.

And maybe there’s a hydrogen power rocket that is more efficient than our fire ones.

For traditional rockets, it's not so much fire, as it is the rapid expansion of matter and the force that it generates. Fire just happens to be the most convenient method for us.

There could be metals under an ocean that could be mined. An underwater civilization could potentially harness nuclear power.

Volcanoes can launch things into space. There are already systems that try to tap into it. So its possible in theory to trigger it underwater.

Land animals are more likely to develop hands. Hands wouldn't give a fish any advantage, because there is nothing to climb.

Building a rocket requires hands, and the type of intelligence that evolves only after having hands.

I don't think this is a great argument. Crabs and lobsters have claws which are almost hand like. And Octopus have tentacles, which can be highly manipulative. So those limbs must give those creatures an advantage even in water. It wouldn't be too much of a leap from those appendages to something as good as hands.

I agree. I made my argument, but think it's flawed now. Appreciate the responses.

> Hands wouldn't give a fish any advantage, because there is nothing to climb.

The ocean floor has plenty of stuff to dig into, pick up, and manipulate, along with un-anchored things like mats of seaweed.

> Land animals are more likely to develop hands.

I can easily imagine sea-creatures making the same kinds of assumptions in reverse: "Sir Blub-blub, while this hypothesis of 'land' animals is indeed intriguing, they would undoubtedly be primitive, far less likely to develop intelligent grabbers. After all, there will be nothing worth grabbing but hard 'dry' rocks! They wouldn't even be useful for propulsion, given the intangibility of this 'air'."

This all pre-supposes that evolution will lock alien organisms into a specific and static body configuration on other planets like it has done to organisms on Earth.

Is there any particular reason why an intelligent organism couldn't evolve to be able to grow and change its body into any arbitrary size and shape that it wanted to merely by thinking about it?

Perhaps aliens from another planet would consider our limitation as four limbed bipedal organisms to be absurd.

Why can't organisms chose to grow eight hands each with 16 opposable digits?

> This all pre-supposes that evolution will lock alien organisms into a specific and static body configuration on other planets like it has done to organisms on Earth.

It's pretty normal for organisms to have drastically different body configurations through their lives. e.g moths

Though I'm not aware of any that have choices to make in the process.

Edit: actually lots of organisms can "choose" to change their sex

What about an octopus?

Vs. tentacles with claws and suckers(with nice sensors embedded). As in https://en.wikipedia.org/wiki/Cephalopod

> From a high level, what is an ocean but a thick atmosphere?

"Now you have two atmospheres."

Ha. Ha ha. Nice.

It would probably be useful for high speed travel. Speedboats can go a lot faster than submarines. Airplanes can go even faster, but they might be a bit impractical since they'd have to be full of water.

Also radio communications since radio travels much better through air than through water. Of course, they could just build antennas underwater and then float them above the surface to use them.

Navigating by the stars would be really useful, and for that you need to be able to see above the surface. I guess you don't need to go above the surface. A periscope would do the trick.

It might also be useful for energy generation. Wind power if the wind is stronger than ocean currents. Or solar because the light is stronger.

Their airplane doesn't necessarily have to be full of water, just like our high altitude (military) planes and spaceships do not have to be full of air. For convenience, yes, but just for survival you'd wear a protective suit with life support systems, just like we do. Edit: But I agree that they'd be impractical for convenient business and leisure travel for the average octopus out there...

> Also radio communications since radio travels much better through air than through water.

There is https://en.wikipedia.org/wiki/Whale_vocalization which carries rather far, if not disturbed by humans.

But with a full water atmosphere in a space ship you would be way more protected from radiation :)

Orcas could very well be smarter than us, but it is extremely unlikely they'll ever evolve hands to build tools - it would be a radical and crippling change in their skeleton with absolutely no evolutionary pressure to do so. Primates (and koalas) didn't evolve hands with opposable thumbs to build tools, we did so because our ancestors got pushed into the trees. And orcas really need their flippers to be good in the water.

"If life evolves on a planet with land, instead of only oceans, imagine how much longer it would take to discover boats and submarines that can travel on and under the water!" - Xenobiologists on K2-18b after detecting possible signs of life on the Sol system's third planet.

Earth had precious little land, if any, over the first billion or so years too. The crust takes time to differentiate and pile up into cratons.

Though in this particular case it looks like the planet is a gas giant, plausibly with a water ocean but without any higher density rocky/metal core to make "land" out of.

I wonder how oceanic life would be able to record information. If we assume that extraterrestrial oceans would have lifeforms similar to corals and barnacles, how would an aquatic civilization prevent written information from getting encrusted with biofouling or keep it from corroding away?

there are so many ways to record things... for example https://en.m.wikipedia.org/wiki/Quipu maybe the need to keep it clean just makes it more important to a society...

By using strings of pearls on fishbones. To the effect of something like this: https://en.wikipedia.org/wiki/Quipu

Or selectively breeding barnacles to make longlasting letters/symbols, or 'milking' their glue and put it on something to avoid being overgrown. Imagine an aquatic market for underwater fonts!1!!

I highly recommend reading Adrian Tchaikovsky's Children of Time series which explores this a bit.

I listened to the series, I enjoyed it a lot.

Overcoming water->land barrier seems comparable to overcoming land->air and air->outer space in the context of rocket launches.

Taking it a step further, being an ocean dwelling creature could even be an advantage in space since they would more easily be shielded from radiation if they were enveloped in a large mass of water and g-forces might be easier on their bodies since they'd be less compressible.

But on the other hand: https://www.smithsonianmag.com/smart-news/fish-dont-do-so-we...

How high are you? :D