Questions tagged [science-based]

For questions that require answers based on hard science, not magic or pseudo-science, but do not require scientific citations. Contrast with the hard-science and reality-check tags. Do not use this tag as the only tag on a question.

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37
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13answers
8k views

How to stop a massive canal system from silting up?

Based on the desert world from this question I need to transport around 500 cubic kilometres of water / year across a desert. Using this calculator. this can be achieved if the main feeder canal is ...
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8answers
7k views

Are diamond berries possible?

Diamonds are carbon. Plants take in CO2 and use the carbon. Chemically, could the right kind of plant have diamonds for berries, or is there some other limiting factor?
37
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7answers
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Can 3 planets rotate around each other like this?

I was wondering if three planets can rotate around each other so that: Two of the planets are smaller and rotate around each other Both of the smaller planets rotate around another, bigger planet. ...
36
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17answers
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What can plausibly explain many of my very long and low-tech bridges?

I have a very large developed (relatively rational) fantasy game world which mostly has medieval technology with some Renaissance technology, and some low-powered magic. In it, when I was much ...
36
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13answers
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Is there a liquid that could protect a human inside it from impact?

I am trying to figure out what kind of liquid, if any, can be used to severely impede or slow human motion without killing or severely damaging their bodies (IE if after being submerged in this liquid ...
36
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15answers
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What methods might an ancient civilization use to desalinate sea water?

Following on from my previous question here concerning the ancient civilization I have called the Androy and their struggle to survive terrible drought conditions on their planet. After years of ...
36
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17answers
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Deadly, Heavier than Air Gas

In a given fantasy world, I need a deadly (yet not magical) gas that will naturally pool in low depressions and valleys. The level of magic is not high, so I'd like it to be an actual chemical that ...
36
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9answers
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What are the effects of slicing the Earth in half with a particle beam?

Scenario: An exact copy of our world is sliced in half by a particle beam. The beam has a diameter of 40 meters and moves at a speed of 0.999c. The beam slices the earth from top to bottom in 600 ...
36
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14answers
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How can hornets be engineered to kill a human with a single sting?

Asian Giant Hornets are particularly vicious and deliver a dose of neurotoxin to its victims. Generally an average of 59 stings are sufficient to kill a healthy non-allergic man Given a suitable ...
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20answers
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Possible Long Term Effects of Frequent Teleportation

This is a follow-up to my previous question, based on one of the comments that was made. While the answers to the original make it quite reasonable that there will be no permanent effects manifested ...
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19answers
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What sort of world would help prevent an intelligent species from discovering evolution?

I’m working on a first contact story set in the near future where an advanced alien species arrives at Earth and reveals itself to humanity, but is utterly baffled by the diversity of life that it ...
36
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10answers
4k views

Managing heat dissipation in a magic wand

Backstory You won't believe it, but I'll tell you anyway. I'm a Level 61 wizard. If you think about it, wands aren't all that hard to use. Point, invoke, joyfully watch your enemy burn in the ...
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23answers
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Economic reasons to put people on Mars?

I am working a hard science fiction story and I cannot come up with a really good reason to put people on Mars. I need people on Mars for the story to work, but there is no reason for them to be there....
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13answers
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Can a river be put under enough pressure to jet straight up for a mile?

I've been mulling over an idea for my preferred RPG setting, and I wanted to check if anyone knows the following: Is it possible for a river to flow underground for miles, and then suddenly be put ...
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11answers
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How does an ordinary person announce major discoveries?

While this is a hypothetical question, I am actually looking for a 'real-world' answer. This is my first time here, so please let me know if I should ask it somewhere else. So, let's say I am an ...
36
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10answers
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Is it more likely that merfolk would evolve with horizontal or vertical tails?

Another mermaid questions I'm afraid! Fish have tail fins which are vertical, whales have fins which are horizontal. My race of merfolk are: Very active (more likely to be warm blooded) Have gills ...
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10answers
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How can I destroy a gas giant planet?

We have already discussed how difficult it would be to blow up a planet like Earth, basically deciding that you can't do that with any reasonable amounts of energy. But what if I don't need to blow up ...
36
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10answers
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No newborns on Earth. How much time to find a cure?

Pretty much what it says on the tin: It's the beginning of 2016. Due to a fast-spreading virus, humans have lost the ability to reproduce themselves. The virus makes current artifical fertilization ...
36
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5answers
13k views

Is diamond armor better than traditional armor?

A medieval alchemist (from Europe) has figured out how to crystallize any object and turn it into diamond. Would diamond armor (e.g. chain mail and plate armor) and weapons be superior to their ...
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3answers
6k views

How many plants does it take to breathe?

I'm working on a space story in which an astronaut is travelling to Neptune to validate our CurrentEarth™ corporation's findings regarding our Solar System. The setting is a moving ship similar to the ...
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5answers
6k views

Can a planet realistically have multiple suns?

Several science fiction books I have read (including, IINM, Nightfall by Asimov) have featured planets with several suns. Some worlds where this happened wrought interesting effects on the inhabitants ...
36
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3answers
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How would a Reflecting-Oven-Jay Evolve?

This answer to my question about light-as-a-weapon came up with an interesting concept: The Reflecting-Oven-Jay This is a small African predatory bird with a perfectly smooth set of wings with ...
35
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17answers
11k views

An object that is gold in one specific area but becomes worthless if you leave that area?

Let us pretend there is some "sacred city" created by gods, where gold is so common that it is the standard form of currency and everyone has lots of it. But once you try to leave the city with this ...
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33answers
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Why would a fighter have a weaker shield than a capital ship?

I enjoy designing games, and in one that I'm working on the ships have shields, similar to the shields in Star Trek. They are created via some kind of force field projection mechanism and are ...
35
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16answers
8k views

Best species to breed to intelligence

I’ve included more background below, but the TL;DR is that you’re a lone immortal who’s decided to breed some species of animal to a human-level intelligence (over the course of hundreds of thousands ...
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12answers
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Is It Possible to Make a Computer Virus That Acts as an Anti-virus?

After receiving answers to this question, I now know that viruses cannot be written in machine code in such a way that they can universally infect all kinds of systems. Every machine has a unique set ...
35
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12answers
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Weaponry made from extreme light-weight steel: swords and daggers

Imagine there was a material that was mostly identical to steel in almost every way, but instead of a density of $7.85–7.87 g/cm^3$ it would be a tenth of that. That is about 4 times lighter than ...
35
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15answers
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Precision Destruction by a Cosmic Being (Or how to destroy StackExchange from space)

We have a lot of weird questions come up in chat and fun comments about how we destroy worlds over a lunch break. Here is one that though I might share. You are a power that can affect cosmic bodies ...
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9answers
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Are external lights on spaceships even necessary?

Many fictional spaceships of all kinds are known to have external lights. Do they even need them? Outer space is lit by the billions of stars and galaxies, so why are there external lights on ...
35
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6answers
6k views

Would a suit that acts as extra-cardiovascular system allow you to run indefinitely?

Generally, when you run a long distance or do something particularly strenuous, you start breathing heavily because of a decrease of oxygen in your blood. Your gasping and weezing is in an effort to ...
35
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7answers
8k views

How far can a time traveller go into the past before his electrical equipment becomes unchargeable?

My time traveller has a maybe 20-minutes-into-the-future smartphone and laptop. They can store large amounts of data, on the Petabytes level or higher. The time traveller can effectively store the ...
35
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17answers
11k views

What society might survive the 3 generation rule

A not widely accepted psycho-social phenomenon but one our descendents might sometime face, the Three Generation Rule states: that the degree of social discipline needed for a space habitat to ...
35
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9answers
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How long does it take to build a medieval city wall?

There is a medieval city that, for multiple reasons, doesn't have any kind of structural defense, but they decided to build a wall now as there is risk of a war in the bordering kingdom, which can ...
35
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6answers
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What's the smallest reasonable natural planet or moon with Earth-like surface gravity?

We all know that equation for surface gravity is $$ g = \frac{4\pi}{3} G \rho r $$ So if we want Earth-like surface gravity of $ g = 9.81 $, then the equation for radius is $$ r = \frac{3 g}{4\pi G ...
35
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9answers
6k views

How would tattoos fare on reptilian scales?

In a world with humanized (or at least tool using) reptiles, how long would a tattoo be able to last on the scales? Would the tools need to be much different than what we use today? Would it be ...
35
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5answers
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What would happen if magic was constrained by the second law of thermodynamics

This is a followup question to the question Wondering what would happen if magic was constrained by Conservation of Energy and it's related to this post. This question asks which sources of energy ...
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16answers
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Is it possible for nature to create bubble wrap?

Bubble wrap is a synthetic packing material featuring small bubbles that are designed to provide cushion to the protected object and pop in place of damaging the object under excessive stress. They ...
34
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12answers
7k views

Is it possible for a substance to be thermally inert?

Heat is energy. Temperature is an indication of the level of heat in a substance. But the normal way to measure temperature is to observe how the substance interacts with its surroundings - most ...
34
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8answers
12k views

Could the Romans have colonised the New World?

The question of whether the Romans could have crossed the Atlantic in a storm has already been answered and the answer seems to be: yes but unlikely. Could the Romans have crossed the Atlantic in a ...
34
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18answers
11k views

How is warfare affected when armor has (temporarily) outpaced guns? How can guns compete?

This a follow up on the previous post that asked how strong graphene armor would be and the general conclusion is that we have no idea sadly. So in this post I will ask a more relevant question. ...
34
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12answers
7k views

Why would astronauts go to space to mine asteroids?

Realistically, if we are ever going to mine asteroids, it would be drones and robots that do it, not humans, because of safety and cost reasons. What reason could justify the participation of human ...
34
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6answers
8k views

How many years before enough atoms of your body are replaced to survive the sudden disappearance of the original body’s atoms?

A magician summons a person to the material world to be their servant. Their body is not made from true atoms per se, but is some kind of force projection. In most ways though, they act as a person ...
34
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12answers
6k views

Super Spies Reality Check

It's a common trope that during the Cold War (and afterwards) America, the UK, the USSR, and sometimes nations beyond these developed super spies, capable of acts of espionage, sabotage, and direct ...
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5answers
7k views

Dyson sphere with mirrors

What would happen if the entire inner surface of a Dyson sphere (not necessarily a solid shell, maybe a very dense swarm) would be coated into a highly reflective material? Let's say it can reflect ...
34
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18answers
5k views

Bare Minimum Tech for Spaceworthy Vessel

In my story, a planet of low-tech natives in the midst of war are abruptly brought into contact with a much more advanced empire. There are many historical precedents for this kind of event, and ...
34
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7answers
9k views

What makes a dragon's scale so tough?

Many fantasy stories involve some variation of a dragon, and while there's a lot of variation in whether or not they fly, if they can breathe fire, how magical they are, etc., the strength of dragon ...
34
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8answers
92k views

What would be the effects on the human body if the oxygen level increased by a lot?

How would the human body be affected if oxygen levels increased by a lot? Our air is 78% nitrogen and 21% oxygen. If it increased to 30% oxygen, what would the effects be and how long would it take ...
34
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19answers
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Which current networking protocol would be the optimal choice for very small FTL bandwidth?

Possibly a dumb and outsider question, but my knowledge in the basics of computer networks is terrible. Imagine the possibly not too original concept, that humanity somehow manages to transmit data ...
34
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7answers
4k views

How to create an annual celestial event for a world

Yesterday while Green, Andy and I were recording new episodes for the podcast we stumbled upon a bit of a problem that we need someone with physics/astronomy knowledge to help out with. We want to ...
34
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13answers
4k views

Finding Earth on a star-map

One day, I am randomly teleported to somewhere else where I meet some aliens. These aliens are very technologically advanced and after figuring out communication, we establish a rapport. The aliens, ...

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