# Tag Info

### Maximum optimal economic growth rate in developed countries in the 21st century

Near infinite (almost). Once upon a time, most economic activity was based on the primary sector, food and raw materials. As a rule of thumb, in classical times and the middle age nine out of ten ...
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### What is the minimum specifications for a ship to survive propulsive reentry?

If you have engines that can exceed 1g and you have enough delta-v then your ship has no problem surviving a propulsive entry--you can slow it as much as you need to, the engineers who built it can ...
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### What is the minimum specifications for a ship to survive propulsive reentry?

Fortunately, there is in real life a space transportation services provider named SpaceX who routinely and frequently posts on YouTube complete videos of their missions, which in recent years have ...
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1 vote

### Could bioengineered trees grow high explosives?

Proteins A major focus of genetic engineering fundamentally works by creating certain adjustments to the genetic code of an organism, such that the organism is able to produce certain proteins that it ...
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1 vote

### How much food/drink would it take to properly feed 6 inch vs 72 feet people if the amount they need to eat stayed proportional to normal sized humans?

300 calories and 30 million calories. Homework Do a more detailed search and check are the figures for calories or KiloCalories. Human food labels are called calories but are actually KiloCalories (...
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### How much food/drink would it take to properly feed 6 inch vs 72 feet people if the amount they need to eat stayed proportional to normal sized humans?

If the amount of food required to feed a 6 inch person were proportional to that of a normal sized human, it would take an absurdly small amount to feed them. The daily calorie intake for an adult ...

### How much food/drink would it take to properly feed 6 inch vs 72 feet people if the amount they need to eat stayed proportional to normal sized humans?

700 kilocalories for the small guys 50'000 to 60'000 kilocalories for the big guys Usig the Katch-MCArdle formula it comes out to be around 500-700 kilocalories per day for very active humans that are ...

### How much food/drink would it take to properly feed 6 inch vs 72 feet people if the amount they need to eat stayed proportional to normal sized humans?

How to scale? Going from approx. 6 feet to approx. 6 inches, while retaining the proportions, would reduce the body mass by $\frac{1}{12^3}$, so arguably the energy use by organs and muscles should ...
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### What phonemes would a snouted animal (e.g. dog or cat) be able to pronounce?

I would strike a balance between understandability (for readers/listeners), effect, and realism. It would be burdensome to read a long book with extreme accents for main characters or dominant ...
1 vote

### How large would a tree need to be to provide oxygen for 100 people?

How large would the tree be? Trees release O2 when they absorb CO2 into themselves. So, it's not a question of how big the tree is, but of how fast it is growing. One person consumes ~400L of oxygen ...
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1 vote

### How large would a tree need to be to provide oxygen for 100 people?

I think that the tree would have to be really large with long branches and leaves, covering like 100 or 200 meters wide, each leaf double the size of a normal tree thus generating much more oxygen and ...
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### What is good Armament and Protection for a Quadruped Mecha?

Armour You are worried about things hitting the walker from below? Slap some armour on there! Heavy armor makes shells and bullets and broadswords go plink plink and do zero damage. Put armor on the ...
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### How large would a tree need to be to provide oxygen for 100 people?

Most of the mature tree is not the living tissue. The substance we understand as "wood" is the dead tissue that still serves its function of water transportation and mechanical support. ...
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### Help with my ocean currents

The broad strokes of the modern day currents are driven by the large scale atmospheric circulation (Hadley cells, the westerlies and the trade winds etc). This structure is related to the Sun and the ...

### What is good Armament and Protection for a Quadruped Mecha?

Slaughterbots A giant mech is a walking target with many weak spots. Damage the joints and it can't move anymore. It's a giant mobile weapon platform. The best defence is a drone swarm A cloud of ...
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### What is good Armament and Protection for a Quadruped Mecha?

Ball turrets! ball turret image source The problem you note is the same as that encountered for the B17. The solution: ball turrets! https://en.wikipedia.org/wiki/Ball_turret These cunningly ...
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### Suspending An Object in Time

Problems and weirdness with stopping time Time is very elusive. Imagine firing a cannonball and taking single 'frozen' moments in time of it. Each time you look at the ball you notice something ...
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### What is good Armament and Protection for a Quadruped Mecha?

A near-present-day solution? You mount EM-SHORAD turrets (or an analogous system) on its belly. Laser cannons of multiple tens (or, with the tech level you're apparently working with, hundreds or even ...
• 10.8k
1 vote

### What is good Armament and Protection for a Quadruped Mecha?

Without knowing what sort of Tech-Level your Mecha is dealing with, it's hard to answer. However, to protect the lower glacis, I'd go with a Hard-Kill Active Protection System like Trophy, but ...
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### What effects would a Jupiter-like gas giant's magnetosphere have on a human civilization on its habitable exo-moon?

The possible habitability of exomoons orbiting exoplanets in other star systems is a topic in astrobiology, the theoretical study of the possibility of life on other worlds. If exomoons can be ...
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1 vote

### How to design a geckskin grappling hook to attatch to surfaces like a rocks and builidngs?

I'm not much of an engineer, but I thought I'd mention that I recently saw this video by Veritasium about a similar material to the one you're talking about (or perhaps the same one). The video could ...
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### How large would a tree need to be to provide oxygen for 100 people?

163,200,000lbs or 74,026,275kg plus 5% per year for everyone. Or 1 general sherman just for the elves. Assuming you have a way to contain the gasses. It takes six molecules of CO2 to produce one ...
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### How large would a tree need to be to provide oxygen for 100 people?

Ultimately, the carbon cycle (between CO2 and food) is a closed cycle, so a tree or plant that can provide oxygen for 100 people could, if edible, provide enough food for 100 people. That should give ...
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### How large would a tree need to be to provide oxygen for 100 people?

It seems small, faster-growing plants are a better bet than most trees. You might want to follow what this bloke does. Reply to comments: Yes, it would be nice to have families live in a. single giant ...
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### Would an aircraft covered in radiation-absorbent sponges be invisible to radar?

You could. But I think that would make your aircraft slower and more visible. The better approach is to make your aircraft with no upright surfaces to reflect sideways-looking radar back where they ...
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1 vote

### Could a sufficiently heavy element serve as a muon source to catalyze nuclear fusion?

So, no. A muon is like an electron, only 207x as massive. If an atom has a muon instead of an electron, its shell is much smaller than that of an electron shell. You initiate fusion by shoving atoms ...
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### Could a sufficiently heavy element serve as a muon source to catalyze nuclear fusion?

To your first query No. There is no such element (as far as we know) that could have muons instead of electrons. As I read it, you have the misconception that muons are rarer forms of electrons (I ...
• 1,411
1 vote

### Could a sufficiently heavy element serve as a muon source to catalyze nuclear fusion?

You want muonium. https://en.wikipedia.org/wiki/Muonium Supposedly it is short lived but under certain cirumstances it can be trapped in crystals. A SEARCH FOR ATOMIC MUONIUM IN CHEMICALLY INERT ...
• 302k
Accepted

### Would an aircraft covered in radiation-absorbent sponges be invisible to radar?

Current stealth airplanes are covered in radiation absorbent materials and paints, adding also geometry designed to deflect radar away from the receiver. This doesn't make them invisible, they only ...
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### How large would a tree need to be to provide oxygen for 100 people?

A small frame challenge: Scaling up a tree will not provide more oxygen, as, absent some new biochemistry, larger trees tend towards net neutral oxygen production, eventually becoming net oxygen ...
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### How large would a tree need to be to provide oxygen for 100 people?

From https://space.stackexchange.com/questions/26668/how-many-plants-would-be-needed-to-produce-oxygen-enough-for-20-humans – "A 100-ft tree, 18" diameter at its base... very roughly, seven ...
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### What effects would a Jupiter-like gas giant's magnetosphere have on a human civilization on its habitable exo-moon?

Your people need protection! That Jupiter radiation is charged particles. They are tough on things. If they go through your eyeball you see flashing lights. Your people need protection. You could ...
• 302k
Accepted

### Could a biological organism have organs that perceive entropy?

Think smarter, not harder. While I don't plan on press the same key again, this feel like a pointless thing given what it'd take. For starters, entropy itself is not something that can be observed, ...
• 13.9k
Accepted

### Could my planet sustain life?

Part One: Planetary Size. You should specify what you mean by your planet having about 1.25 the size of Earth. If you mean that it will have about 1.25 the volume of Earth, it will have about 1.0775 ...
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### Is it possible for a living creature to have no need for oxygen or some other gas

Here's the problem: here on Earth nearly all living things require oxygen because it's the most convenient, plentiful, and non-toxic oxidizing agent. Oxidation could realistically be called the center ...
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### Is it possible for a living creature to have no need for oxygen or some other gas

The fundamental problem here is that almost no life on Earth works this way because it's very inefficient. Oxygen is by far the most energetic oxidizing agent available and thus anything using it in ...
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### What would be the ideal reaction mass for hall-effect engines?

Xenon, Krypton, or Bismuth The noble gases xenon, krypton, and maybe argon are likely to be used in far future Hall-effect thrusters. They are relatively common elements, so no need to mine gas giants ...
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### Is it possible for a living creature to have no need for oxygen or some other gas

Anerobic bacteria get by just fine without oxygen. According to the laws of thermodynamics, the driving force of change in a system is disorder, which must always increase. There are two ways of doing ...
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### How many days in a week, and weeks in a month, would be needed for this specific lunar cycle?

Your moons are going to change phase all together. Sorry. That is how phases work. Think about why our moon has phases. It is because of the direction the sunlight is coming from. From the ...
• 302k
1 vote

### Could my planet sustain life?

Use your moons to stir it up a bit Q: "if life couldn’t evolve on this planet, what features could I change in order for it to be possible?" Your design includes the moons as well. Now ...
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1 vote

### Could bioengineered trees grow high explosives?

Explosives require the mixture of a fuel and an oxidant. These can be in separate molecules, as in gunpowder (charcoal and sulphur fuel, potassium nitrate oxidizer) or in the same molecule, where ...
• 2,787

### Coldthrower and other stuffs

I don't understand much of your post beyond the first sentence. I'll just take it to mean "Could a coldthrower weapon be developed, and how would it work?" I'll further assume that you want ...
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### Is it possible for a living creature to have no need for oxygen or some other gas

living creatures as we know them need oxygen This is very untrue (as you indeed acknowledge). Anaerobic life is common. Even humans and other higher mammals have many anaerobic metabolic pathways. In ...
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### Is it possible for a living creature to have no need for oxygen or some other gas

May depend on your definition of breathing. My first thought was the fish; however absorbing oxygen directly from seawater (pumped through gills) still meets your definition of breathing, and ...
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### Is it possible for a living creature to have no need for oxygen or some other gas

This led me to thinking that there could be alternative ways to produce energy rather than breathing in air. Of course there are. There are small sealed glass balls for sale with plants inside, ...
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Accepted

### Is it possible for a living creature to have no need for oxygen or some other gas

Strictly anaerobic. I proposed a giant sea creature that would not need to breathe because it metabolized its food using anaerobic glycolysis. Could a deep ocean creature use some kind of bacteria in ...
• 302k
1 vote

### How would micromachines communicate?

Nanomechanical computers are more compact and are a billion times more efficient then semiconductors. a neural network made of microbots with nanomechanical processors would have far more room and ...

### Could my planet sustain life?

Earth looked a lot like that for about a hundred million years. This is commonly called "snowball Earth" -- a period when, due to the way the continents had drifted and joined, the Earth ...
• 44.1k
Accepted

### How many days in a week, and weeks in a month, would be needed for this specific lunar cycle?

This looks like a case for Grey Codes! Grey Codes were always one of my favourite parts of computer science. In short, it's a way of ordering binary values so that every step changes only one bit/...
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