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Questions tagged [hard-science]

Requires answers backed up by equations, empirical evidence, scientific papers, other citations, etc. Contrast with: science-based and reality-check tags. This tag should never be the only tag on a question because this tag frames how a question should be answered, not the topic. Review the tag info before using this tag, and flag your question for moderator attention once posted to have the hard-science notice added.

5
votes
3answers
256 views

Mega-human: What are the largest possible dimensions of a human? [duplicate]

How big can a person be while retaining all the functions of all their organs (including bones)? I am wondering if it is possible for large people to exist without compromising some part of their ...
3
votes
4answers
248 views

How can I measure the distance between two stars? [on hold]

So I am doing a write-up for a world setting set in our galaxy. I know the distance from Earth to the different stars in Light Years. However I am now trying to figure out how to measure the distance ...
14
votes
3answers
225 views
+100

How to calculate the loss of primordial heat for a given age and mass of a planet?

I´m working on a computer program which generates realistic planets for worldbuilding purposes. I´ve run into an issue with calculating my planets heat loss. While radiogenic and tidal heat generation ...
13
votes
1answer
226 views

What would happen to air flow and fires in an O'Neill cylinder?

I was curious: Suppose we built an O'Neill cylinder with an air mixture similar to Earth's (not pure oxygen). Does the air also get "thrown" down towards the floor of an O'Neill cylinder? If I ...
7
votes
1answer
169 views

How much energy can I produce per kg of hydrogen using this process?

In the far future the posthuman successors of mankind have disassembled the stars and live on ultra slow and ultra efficient solar system sized computers, Matrioshka Brains. The last enemy of ...
64
votes
21answers
17k views

Is it possible to kill all life on Earth?

Edit: It has been suggested that my question is a duplicate of What could humans do to render the earth uninhabitable?. That question only asks what would be necessary to make human life ...
4
votes
2answers
196 views

A Dozen Cubic Miles of Volcanic Ash--How Big Would the Cloud Be?

On May 18, 1980, Mount Saint Helens made American history with an eruption that took 57 human lives and killed thousands of animals. It has released only a quarter of a cubic mile of ash, but it is ...
9
votes
14answers
3k views

Natural Armour and Weapons

In my fantasy world, the magic system pretty much makes metal armour and weapons obsolete. The magic system's specifics aren't important, just note that the magic system allows the users to 'penetrate'...
33
votes
8answers
6k views

Of strange atmospheres - the survivable but unbreathable

Most gases that are toxic to breathe also do nasty things to the skin when they're in the atmosphere at dangerous concentrations - and one is walking around without sealed protective clothing; sulfur ...
10
votes
3answers
459 views

Can I render satellite deployment impossible, or at least impractical, by exploiting the Kessler syndrome?

I want to render impractical the deployment of satellites by exploiting the Kessler syndrome. Why, you ask? Maybe I'm an evil overlord and I don't want those pesky satellites flying over my lair. ...
-1
votes
3answers
237 views

How many babies can a human women safely be pregnant with at once? [closed]

Most pregnancies result in 1 baby, sometimes there are twins. Every now and then there are triplets. My guess would be that 4 at once has happened before too. But 5? How about 6? Surely not 7. How ...
1
vote
3answers
211 views

What are the harmful consequences of burning cigarette stubs in large quantities?

I have a pair of survivors living in a trailer (18-wheeler's trailer) and they have found about 3 pounds of cigarette butts and have decided to burn them for warmth. What would happen to these two? (...
-4
votes
1answer
91 views

A slowly cloning atom? [closed]

There is a single atom of handwavium which then splits into another atom of handwavium every hour (the second atom also has the clone ability). my question is how many hours would it take for these ...
13
votes
4answers
2k views

With today's technology, could iron be smelted at La Rinconada?

La Rinconada, Peru is notable because it has an effective oxygen concentration of only 11%, leading to the need for special techniques just to keep a fire going, and preventing the use of combustion-...
10
votes
1answer
526 views

What's the useful range of atmospheric oxygen content for fire?

Fire is certainly high up on the top ten list of mankinds most useful inventions. It allows for a more efficient utilisation of nutriants, is the basis of chemistry and the material sciences, allowed ...
3
votes
3answers
228 views

Solar cells in the Renaissance

An engineer goes back in time to attempt to rewrite history: since global warming has wiped out all but a few living species at his home timeline, he wants to prevent it without preventing an ...
3
votes
1answer
141 views

Brown Dwarf Star vs Gas Giant as parent for habitable moon

I seek to build a habitable moon of a giant planet, thus I looked at the Rouche Limit Equation to figure out how to get the biggest possible Hill Sphere for my moon to exist in. $r_H = a(1-e)\sqrt[3]{...
4
votes
3answers
108 views

How would digital currency work on a intergalactic scale with limited FTL loopholes?

Another question got me interested in this. How would finances work when there would frequently be long delays for confirmations of transactions? Let's say there are Jump Gates/Artificial Wormholes at ...
1
vote
1answer
89 views

What chemicals can be used as an alternative fuel in an Internal Combustion engine, that are environmentally friendly? [closed]

As most people know, not all animals on earth benefit from humans driving vehicles that warm the globe and produce horrible chemicals, such as Carbon dioxide and Nitrogen oxide. My question What ...
33
votes
0answers
973 views

How soon can the first stars form?

Introduction In our universe, the cosmic microwave background was formed approximately 400,000 years after the Big Bang. It was hot, but within a few million years after the Big Bang, it would no ...
19
votes
13answers
7k views

A non-technological, repeating, phenomenon in the sky, holding its position in the sky for hours

Is this physically possible? A non-technological phenomenon visible in the same position of the sky, for 18 hours of a day using the other 6 to do whatever, rise and set, just be impossible to see, ...
1
vote
1answer
193 views

Creating a wormhole connecting two universes with different spacetime metrics?

A civilization wishes to create a wormhole connecting its universe to a universe with a different spacetime metric. For instance if we describe a timelike dimension with $+$ symbol and a spacelike ...
13
votes
3answers
1k views

Black holes as heat sinks

Cooling in space is a well known difficulty. There are many unpleasant consequences like no stealth in space, difficult space battles which turn into a short wars of attrition (because you have to ...
5
votes
2answers
191 views

Atmosphere of a terraformed 10 km planetoid with Earth gravity

Bernal spheres and other O'Neill cylinders are complicated, maintenance-high and fragile beasts. Someone started to make micro-black-holes and put them in asteroids, in order to have 1 to 10+km rock ...
7
votes
4answers
249 views

Aliens in a 4D universe try to explore our 3D spacetime fabric: How can they do it?

They do not necessarily meet humans and try to interact with them. This question is more about the technical possibility/impossibility of 4D aliens being able to "analyze" the inner structure of our ...
3
votes
2answers
199 views

Making iron tools from blood [closed]

So, I read a while ago several threads about making iron objects/blades from blood. In my conworld there are giant predators that would, according to my calculations, have enough blood so that 12 of ...
3
votes
1answer
226 views

Can you forge iron from oxide dust?

I've been looking over the internet and on here to find some kind of evidence for this, but nothing conclusive, so I was hoping for people with a better understanding of smelting, chemistry and ...
4
votes
3answers
160 views

Calculating Wormhole Wind Speeds

Here's something I've never noticed anyone asking when it comes to wormholes/portals: If they allowed air to pass through them, how fast would the wind be? Should atmospheric pressure differences be a ...
6
votes
2answers
136 views

Ice-World / Cryo-World Settlement (amorphous cryolava / cryomagma)

I was watching a program about the New Horizons space probe and was fascinated by the new revelations about cryolava/cryomagma, and the amorphous planes covering Pluto(98% nitrogen ice). I'm ...
7
votes
1answer
89 views

Visibility of a Red Dwarf Companion Star

An interstellar traveller stands upon the surface of an alien planet beneath the light of an unfamiliar sun. The planet upon which he stands orbits one star of a binary system in which one is a G-...
19
votes
8answers
12k views

Car headlights in a world without electricity

In a world like ours in the 1980s, but which for whatever reason does not use any form of electricity. (Either it does not exist or batteries and generators etc have not been invented.) For purposes ...
3
votes
4answers
183 views

Would a monster size aquatic lizard be possible?

So, I am writing a comic which will perhaps grow into an entire series about a group of aquatic heroes. One of those heroes is a monster size aquatic lizard. The story of how this lizard came about is ...
0
votes
1answer
86 views

How much colder would that asteroid make my planet?

I've seen some posts here (for example this one) for the effects of certain sizes of impactors, but I'm not finding any definite answer and all my google and google scholar searches have not turned up ...
19
votes
3answers
4k views

The One-Electron Universe postulate is true - what simple change can I make to change the whole universe?

The one-electron universe postulate, proposed by John Wheeler in a telephone call to Richard Feynman in the spring of 1940, hypothesises that all electrons and positrons are actually ...
8
votes
3answers
195 views

How to calculate the thickness of the ice-layer of a frozen ocean planet/moon?

How do I calculate the thickness of the upper ice layer on cold ocean worlds like Europa, Enceladus, Ganymede, ...? I'm asking this for a programm I'm currently writing. Given/Known is: mass, radius, ...
14
votes
10answers
4k views

Could solar power be utilized and substitute coal in the 19th century?

Would it be possible for a nation with 19th century to very early 20th century technology and history and hot desert climate to utilize solar power for electrical generation as a substitute for coal ...
-5
votes
3answers
153 views

Preventing the Big Bang

I travel back in time to the Big Bang in my time machine. I am equipped with all the present day equipment I need. I locate the infinitesimal 'point' where the Universe would come into existence and ...
2
votes
4answers
329 views

How would a Type I civilization not cook itself?

A type 1 civilization is defined as a civilization that can utilize the maximum amount of energy equal available to its entire planet, roughly 1017 watts for Earth. This is equal to the amount of ...
2
votes
0answers
77 views

What is the minimum tech level for manned flight? [closed]

For instance, a hot air balloon is really pretty simple; I suspect that even thousands of years ago, it would have been possible to make - steam engines existed in 1AD, after all. So, just how far ...
0
votes
1answer
121 views

What would the moon look like if its orbit was highly inclined?

How would the phases of the moon change depending on the inclination of its orbit with respect to its primary's equatorial plane? Earth's moon has an orbit that is rather close to the ecliptic, but ...
14
votes
4answers
5k views

Would mining huge amounts of resources on the Moon change its orbit?

Imagine that humanity builds mining facilities on the moon. We know that the moon has Helium-3 which could be used as fuel for fusion reactors. Also, there are a lot of other resources which could be ...
2
votes
5answers
587 views

Death from old age has stopped, but fertility window is the same. What is the new population equlibrium?

I'm imagining a near-future world where a process can be undergone that will halt all future aging of the body, but the approach causes infertility. Those undergoing it will not have (biological) ...
4
votes
1answer
177 views

Super Strong robotic prosthesis steampunk Style

I'm thinking of a character that has the magical ability to transform parts of his body into technology, similar to Generator Rex or Bleeding armor iron man, but only with the technology that he "...
-7
votes
3answers
249 views

Focused Earthquake by Remote Jumping up and down - Destroy the Palace!

This question draws on an old idea but it is different. The original question is, "If everyone in the world jumps at the same time, will the Earth move?" My question is,"If everyone in one hemisphere ...
9
votes
1answer
188 views

To make a blue moon, what element does it need?

We know that Mars has a reddish color, because its ground consists of iron-based compounds. The moon is grey-whiteish because it consists mostly of silicon-based compounds. What element should the ...
2
votes
1answer
419 views

Splitting the atom with a hammer

In a world of superheroes the job of blacksmith is given to the very strongest of them. Question Is splitting an atom in a human-scale piece of work by using a human-scale tool even theoretically ...
6
votes
1answer
131 views

Feasibility of an Antimatter-Catalysed Ram Augmented Interstellar Rocket (AC-RAIR)

A fictional starship that I am designing functions via a form of Bussard ramjet that uses hydrogen from the interstellar medium as reaction mass, not as fuel. In order to accelerate the propellant, ...
-1
votes
2answers
176 views

Could implanting false memories change someone's perception immediately? [closed]

This question is about how the brain works in that aspect, if it's even known. I mean with the question that a person might react to something with fear, happiness, disappointment, or whatever other ...
6
votes
2answers
316 views

How hot is my dragon?

Little side project on fantasy story with dragons (or wyverns to be exact, but they're equivalent for the purpose). I have dragons roaming the country side, laying waste and ruin in their wake. As ...
10
votes
2answers
314 views

Bouncing Beads of Blood - Just how cold would it have to be?

My heroine has been stabbed - run through the abdomen by a foot-long dagger - and is bleeding to death. She is currently crawling toward her salvation through a very cold place. She is magically ...