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164 votes

What is the utilitarian purpose of artificial waterfalls?

Low-tech climate control: the waterfalls fill the air with spray, which evaporates off and cools the populace. The Romans used to achieve a similar effect with fountains.
Chronocidal's user avatar
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125 votes

What is the utilitarian purpose of artificial waterfalls?

Still water is heaven for proliferating algae, bacteria and annoying insects like mosquitoes. A large city with large bodies of still water is a recipe for plague spreading. Having water on the move ...
L.Dutch's user avatar
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73 votes

A way of getting the water to the top of the tall building without electricity?

In order to get water up to the top of a building, you can either carry it manually, or you can pump it. Pumps don't have to run on electricity. Wind-powered pumps use a windmill to power the pump, ...
AJMansfield's user avatar
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70 votes

(How) can I provide reliable water sources in a world of flying islands?

While I am answering my own question, this is by no means a definitive answer, please contribute your own if you feel there are other alternatives There is a kind of plant in the Andean regions of ...
Miguel Bartelsman's user avatar
70 votes

What is the utilitarian purpose of artificial waterfalls?

Energy storage. You use a form of energy generation with unreliable or periodic output. As a form of energy storage you pump water up into a nice big reservoir when you have surplus, then power ...
Joe Bloggs's user avatar
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65 votes

Sailing without wind, but with strong currents

You can't control your direction in a sailboat when there is just one current. Sailboats are only able to move into a different direction than the wind is blowing because they have a "second sail" ...
Philipp's user avatar
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65 votes

Pressure inside an infinite ocean?

You won't be able to have this in a universe that uses our physics. The degree to which space itself expands or contracts is related to the cosmological constant and the density matter within that ...
Yakk's user avatar
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65 votes

How long could a person survive on nothing but water, salt, and sugar?

Warning: the links go to medical Wikipedia pages and they show bodies that look quite ill. Follow with caution. Just isotonic sugar water will likely lead to death by scurvy, beriberi, and kwashiorkor,...
Trish's user avatar
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59 votes

What is the utilitarian purpose of artificial waterfalls?

You're looking at it backwards. Nobody added artificial waterways to a city. They did what they had to do to support building a city on top of existing waterways. Human settlements naturally spring ...
bta's user avatar
  • 8,139
57 votes

0g pool: can I keep a big ball of water in space?

Yes, this is possible. The ball of water could be kept in place with equally spaced air fans to nudge splashed water back from all directions. However... At 10 metres across (5 metres deep) there is ...
rek's user avatar
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57 votes

0g pool: can I keep a big ball of water in space?

There is a 0g pool available for the guests. I want it to be a large ball of water 10m in diameter. Can it work? I don't think you can make this work as you've envisioned it. Let's look at some of ...
Rob Watts's user avatar
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54 votes

A way of getting the water to the top of the tall building without electricity?

The oldest pump in historical records is the force pump. The book that first describes it was written between 15 and 30 B.C/B.C.E. This is the Archimedes's screw, which is one of my favorite ancient ...
The Square-Cube Law's user avatar
52 votes

Are 'tree waterfalls' possible?

No, at least not with classical trees. A tree can be defined as a woody perennial plant, typically having a single stem or trunk growing to a considerable height and bearing lateral branches at ...
Dragongeek's user avatar
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51 votes

Closest Proximity of Oceans to Freshwater Springs

What is the closest I can realistically have my spring to the ocean? 0 meters When, as a kid, I went to the sea during summer, it was common knowledge that, in some places along the coast, there ...
L.Dutch's user avatar
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48 votes

Feasible and rational way to give food and water to a prisoner?

In medieval times, this was given quite a lot of thought as castles were designed in most cases to survive a siege. Food is an issue during a siege to be sure, but water more so; this ties into the ...
Tim B   II's user avatar
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47 votes

All of the freshwater on Earth has suddenly vanished - would humanity survive?

Depending on the temperature you are exposed to, you can go 100 hours without drinking at an average temperature outdoors. If it’s cooler, you can go a little longer. If you are exposed to direct ...
JBH's user avatar
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42 votes

What methods might an ancient civilization use to desalinate sea water?

Reverse osmosis. from Aristotle, Meteorilogica. There is more evidence to prove that saltness is due to the admixture of some substance, besides that which we have adduced. Make a vessel of ...
Willk's user avatar
  • 305k
39 votes

(How) can I provide reliable water sources in a world of flying islands?

Fundamentally you need a large enough body of water for evaporation to occur. There are two options, the simplest is just to have a "water world" with an ocean down below and have the islands ...
Tim B's user avatar
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39 votes

How to create tides in a small sea?

Rocking Your continent is floating. Maybe it is rocking back and forth as it floats. That can happen with floating things. Any number of forces can put a body into an oscillating motion. As ...
Willk's user avatar
  • 305k
39 votes

How could an organism store a massive amount of water?

Water volume isn't a problem. The mass is the problem. Your body is somewhere around 60% water. This means even a perfect water storage mechanism can only be about 66% more efficient. You can't ...
Cort Ammon's user avatar
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39 votes

What methods might an ancient civilization use to desalinate sea water?

You can build a solar still using nothing but pottery tubes, sealed with asphalt or similar. A single unit (different design) can produce as much as five liters per day. For continuous production, ...
LSerni's user avatar
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39 votes

Would this system work to purify water?

Do it like it's done on Earth Using filters and machinery is useful when you need it fast or compact but on a generational ship, it's materials you can't spare. You need garden/agricultural areas ...
Thorne's user avatar
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39 votes

Is it biologically plausible for a land animal to drink saltwater and not drink freshwater?

In animals found on Earth, the ability to drink sea water is dependent on the ability of the kidneys to export salt without damage. Sea mammals can do it -- seals, sea lions, manatees and dugongs, ...
Zeiss Ikon's user avatar
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36 votes

Would it be possible to make a water mill without metal?

It is very possible. It's been done. The wheel itself can clearly be made out of wood, as many are even in societies that have metal. The axles and gears that transfer the rotational energy are ...
Jared K's user avatar
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35 votes

How could the rain fall slower?

What you need is much, much lower terminal velocity for raindrops. Using mathematical terms, terminal velocity—without considering buoyancy effects — is given by$$ V_\text{t}= \sqrt{\frac{2mg}{\...
Mołot's user avatar
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33 votes

What would realistically happen if you could water walk?

It will be WAY harder than it sounds Not sure if you've ever seen these floating lilly pads at any public pools, but they work more or less as described. The below body of water is completly still, ...
Nosajimiki's user avatar
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32 votes

How to make sure humans do not know the meteorological phenomenon rainbow?

You need to have direct sunlight that can be dispersed to see a rainbow. If you have only already dispersed light, no rainbow can occur. If you have a permanently cloudy atmosphere (like it is the ...
Thern's user avatar
  • 446
29 votes

Logistics Problem With Water Creation Magic

Your question already contains the answer: There's a facet of my magic system that uses a certain kind of crystal to create water out of the magic energy stored within. The amount of magic energy ...
Otkin's user avatar
  • 6,665
28 votes

What could cause the world to be almost completely submerged in water, naturally or man-made?

The idea of an ocean planet isn't too far-fetched. There are several moons in the Solar System - Enceladus and Europa, for instance - that have subsurface oceans. If the ice covering their surfaces ...
HDE 226868's user avatar
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28 votes

A way of getting the water to the top of the tall building without electricity?

Steam it up with a solar concentrator. This London skyscraper can melt cars and set buildings on fire The building — designed by internationally renowned architect Rafael Viñoly — is a dramatic ...
Willk's user avatar
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