93
votes
Is it harder for an intelligent octopus to live on land, or a human to live in space?
You can see octopodes crawl out of a tide pool and into a neighboring pool with little difficulty. octopodes have been known to crawl out of a tank in an aquarium and have the crab in the tank next ...
- 4,457
85
votes
Could a person scuba diving take off his air tank and use it to propel himself?
My question is, would it be physically possible to do that with the air tank?
No.
Source: Tried it.
We've actually been taught to breathe off a tank without a regulator. You can do so by ...
- 5,894
81
votes
Is it harder for an intelligent octopus to live on land, or a human to live in space?
Octopodes are not going to colonize land the same way we've colonized space - they're going to colonize the land the way we've colonized the sea.
Penguino has done a pretty good of addressing how ...
- 7,400
54
votes
Accepted
Could a person scuba diving take off his air tank and use it to propel himself?
Here is a way to bypass the issue
Our hero removes his air tank, points it away from himself and starts fumbling to undo the top. It's not working! He's never opened one of these things himself let ...
- 66.3k
53
votes
Accepted
In an underwater society, would the wheel ever be invented?
Probably, but it depends on a couple of things
Firstly: The weight of the loads they're trying to move. If they only ever move things that can be easily pulled into the open water there is no reason ...
- 66.5k
53
votes
Could a jet engine that uses water as fuel work?
Let's analyze this step by step.
First, you wouldn't be using the water as fuel, but as reaction mass, like an ordinary jet engine uses air.
You can't really compress water, fortunately, that's not ...
- 7,898
52
votes
Looking for a soft substance that doesn't dissolve underwater
What you described is an old invention:the wax tablet.
Spermaceti from sperm whales is just one of many waxes your underwater people could use. Some of the fishes also contain significant quantities ...
- 33.4k
51
votes
Why would mechs be used in underwater combat but not on land?
Heat
Mechs are inefficient temperature-wise, being submerged in water helps them dissipate heat quickly, which allows them to operate longer than few minutes on land before overheating
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47
votes
Accepted
How would an underwater race protect against pressure waves?
Bubble curtain.
https://www.eurotrib.com/comments/2012/9/6/165418/5127/3
Depicted - an oil rig with a circumferential bubble curtain to reduce underwater noise.
https://en.wikipedia.org/wiki/...
- 306k
44
votes
How to make "humans" that can hold their breath for a long time?
The Bajau People
What you're looking for might already exist in a group of real people in southeast Asia known as the tribes of Sama-Bajau or the "Sea Nomads".
They live in a culture where ...
- 2,006
42
votes
Why would mechs be used in underwater combat but not on land?
There are a few reasons not to use mechs on land, with one of the main ones being that the joints are unable to support the weight of the body if the mech is too large. For details see
Plausible ...
- 888
40
votes
Accepted
How safe would deep-sea investigation of a nuclear battleground be?
We already did this. And oh boy, what a mess.
The target wasn't a sea monster, but the Japanese battleship Nagato, Yamamoto's flagship at Pearl Harbor. And it wasn't any Tsar Bomba, just an ordinary ...
38
votes
How expressive is a color-based language?
Binary
Consider how complex a computer is and what it is capable of, yet all its code is composed of almost the most rudimentary elements possible: zeros and ones (binary code). So, the computer ...
- 6,381
38
votes
Accepted
What would happen to a human body subjected to extreme water pressure?
You would die quite instantly.
L.Dutch's answer is accurate if you do the shift on a reasonably short timescale. But if you do it really fast, which I'm getting the impression is your goal, the ...
- 133k
38
votes
Could a jet engine that uses water as fuel work?
You have updated the venerable pop-pop boat.
Pop-pop boats are sweet. They boil water and use the steam for propulsion. The vacuum caused by the steam leaving the boat causes the water reservoir to ...
- 306k
34
votes
How would an underwater race protect against pressure waves?
A bubble curtain is a decent idea, but for something more static, that doesn't require continuous power...
A sponge wall.
You want a series of baffles that will allow water to pass through, but will ...
- 42.7k
33
votes
Is it harder for an intelligent octopus to live on land, or a human to live in space?
There are a few issues that need to be considered separately:
Constructing water-filled environments for a water-breather to reside in on land isn't a significant technical issue. The manufacturing ...
- 7,566
33
votes
Could merfolk cook without air by using electrical heating?
Consider Not Cooking
For starters, electricity and water are not a great combination. Your merfolk are as likely to cook themselves as anything else.
Beyond that, ask yourself if they need to cook at ...
- 106k
32
votes
Accepted
What is a medieval technology method of underwater enemy detection?
Marine watchdogs.
First option:
Build a net wall around the city in the water like torpedo nets. Inside the net give a cautious and jumpy sea dweller a home. The net has no warning function, it ...
- 14.7k
32
votes
Could a submarine 'sail' the ocean currents?
Sailing actually requires two separate mediums for it to work. Sailing ships tack based on the wind pushing the sail, and that presses the keel of the ship against the water. The direction of the ship ...
- 17.8k
32
votes
How could an aquatic race hunt land animals?
Same way we catch what we want. Bait or traps. Stand on the wrong bit of seaweed and you sink into a trap.
Pigs and dogs will go out at low tide looking for food, so set something up that they can see ...
- 28.4k
31
votes
Underwater acoustic muffling/dampening and sonar evasion. Is a stealth torpedo possible?
Fishpedo
You want stealth. Then be stealthy. Blend in. The ocean is full of fish. Look like a fish. Move like a fish. Have the sonar profile of... you get it.
The sub cannot destroy every ...
- 306k
31
votes
Are there any structural materials suitable for production underwater?
Domesticated Molluscs
Giant clams are just one sort of shellfish, but there are potentially many others of various shapes and sizes. You don't even need to grow clams this big so long as you are ...
- 85.8k
31
votes
In a single-continent world, what could cause hydrothermal vents?
You can have tectonic plates even on a water world, that is still "land" under there, you just have enough water to cover it all.
In your case, any tectonic plates carrying enough land to break ...
- 34.8k
30
votes
Accepted
What kind of weapons would still be effective under water?
Basically everything that you thrust.
The issue with underwater combat is, as you mention yourself, the drag. Thus every weapon that relies on swinging or other movement in order to abuse its weight ...
- 12.1k
30
votes
Accepted
What are the considerations for waterproofing a building's first few floors?
Well, I think the city founders should maybe respect the Dutch a little bit more, because they don't know what they're getting into.
First and foremost, salt water is incredibly corrosive. There's no ...
- 34.7k
29
votes
Could a person scuba diving take off his air tank and use it to propel himself?
First of all, holding your breath while emerging from a deep dive is a really bad idea: the air in your lungs will expand as you approach the surface and will turn you into a balloon, probably killing ...
- 301k
29
votes
Accepted
Weapon design for underwater hand-to-hand combat
He is strong enough to swing swords and other melee weapons despite the water resistance
Swinging stuff underwater is a massive waste of energy, and even if you're hella strong you'll find that you ...
- 78.5k
28
votes
What's a reasonable environmental disaster that could be caused by a probe from Earth entering Europa's ocean?
The Europans are terrified of what the probe means.
The probe does not do anything more than it was supposed to do. But it is recognizably an artifact of an advanced alien culture. That means aliens ...
- 306k
27
votes
Accepted
A drinks party underwater?
Edible water bottles!
Scientists have invented spherical water bottles made out of agar (which comes from the sea) that can be bit into and swallowed (you can find them here) and learn how to make ...
- 4,454
Only top scored, non community-wiki answers of a minimum length are eligible