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Now that FTL travel is here there are all sorts of family outings we can go on. One of these is a scale model solar system lovingly made by hobbyist Barty Slartfast. In full scale Sedna is thre...
How small could our Sun be and still "burn" with nuclear fusion and emit the same spectrum of light and other radiation as the real Sun does? Edit: The goal is to have a small sun inside a huge v...
What would be the diameter and rotational speed of an O'Neill cylinder on the inside surface of which centrifugal and coriolis forces are equal to "gravity" and coriolis force on the surface of Ear...
Background: The moon has been selected as the base for human space exploration. Rather than ship tonnes of material out of earth's gravity well, interplanetary spacecraft and space stations will be...
How can I predict the color of the sky based on the information provided? Atmospheric composition: | 2% Trace gases | 58% Nitrogen | 26% Oxygen | 11% Argon | 3% Carbon dioxide | Average s...
I was having fun reading this article about making cement on the moon when I asked myself (and now you), is it possible to make a suitably high-compressive-strength cement on Mars? Since concrete...
Suppose you could pump a load of energy into an asteroid at a safe distance. As energy gets added to the object, does it make sense that this could be done in a way to get the asteroid to different...
I have a planetary system in which there is a huge planet and a moon orbiting it which has an atmosphere and water (and actually everything needed to sustain life). Thing is that I'm sure the mass...
So my story is set in the TRAPPIST-1-system and a rogue planet enters the system. When it's still far off, a scientist discovers that one of the numbers is slightly off. (She has some tables that p...
In my fiction I'm setting up a civilization which uses Laser Propulsion for moving things between bodies within a solar system (assume Earth/sun analogy). Laser Units have been set up anchored to a...
I'm currently outlining my science fiction novel which deals with humanity reaching Type 3 civilization status. My goal is to place an emphasis on hard science fiction while featuring fantastic tec...
In my story a man who works in Military Intel gets early warning that a nuclear attack on his base is inbound. He abandons his post, grabs his wife and kid from on base housing, and books it out of...
I'm making a mostly ice planet with two moons. For the purposes of this question, let's assume that they are both proportional size and distance to the size and distance to our moon. Both are tidal...
Suppose that there is an alien spacecraft travelling towards the Sun. This spacecraft is similar in design, size and power output to Voyager 1 and Voyager 2 as they were immediately after launch fr...
I'm writing a cyberpunk novel where one of the characters has an augmentation that allows them to echolocate. The idea is that there is a device on the center of his forehead (is there a more opti...
Lego representations of Earth have been made at various scales, for example this one: Suppose Slartibartfast made a full-size Earth from Lego (including the oceans being represented as solid blo...
I'm building a moderately hard scifi future setting that focuses on space and land warfare and I'm trying to decide what would be the most realistic from an engineering standpoint of artillery tec...
Pathogen Note: For the purpose of this question I define a pathogen to include viruses and/or bacteria. Edit: I don't exclude other biological agents such as fungi that might have the same effect...
I'm sure most worldbuilders will have heard the aphorism that in space "Everyone sees Everything", or that "There Ain't No Stealth In Space". I'd like to propose a possible solution to this. Th...
My question is pretty basic, would square thrusters and RCS ports have any real drawbacks over round ones? I know that angles on windows for airplanes is a problem because of the pressure, so I don...
Prior to the Cambrian, there have been three separate ice ages--the Huronian, from 2.4 to 2.1 billion years ago; and the two Cryogenian ice ages, from 720 to 635 million years ago, split in such by...
Human physiology is adapted for life at 1G, but planets colonised by future humans will likely have different surface gravities. What is the range of values for surface gravity that humans can com...
This question has been rewritten to incorporate all clarifications. On Earth, half the planet is illuminated at any time (let's ignore eclipses). Axial tilt lets day lengths vary, but over the cou...
There are several previous questions concerning concentric shells. I won't reference them here because this is different. I understand that there is no gravitational effect inside a concentric she...
I have been working on a sci-fi story for a little while now, and have recently discovered that I made a very big error in assuming the position of Eris. The main issue is that I had forgotten to t...
If I was affixed to the surface of some solid spherical body in space (so as to ignore effects like me floating away), would it be possible for me to throw a tennis ball so that it went into orbit ...
It has been determined by observation of the stars that the gravity on Flat Earth is due to it accelerating upwards at 1G. This is what holds people and objects to the surface. It has also been det...
Considering the well-established relationships between stellar mass, surface temp, and luminosity, how unusual would it be to find a star (or brown dwarf) that possesses about half the mass of an a...
In another question Everybody has a brain implant. What measures can a criminal take to escape justice? I assumed that a brain implant would be possible in the future for surveillance. In this que...
For my hard sci-fi story, I would like to have a planet similar to Titan (very cold, nitrogen atmosphere, methane seas) but with a surface gravity in the region of 1g. Could this occur, or would th...
I ran a quick calculation, and the mass of iron required to form a black hole is on the order of 10^40kg. So, suppose that in my story there is this almost much iron available to somehow be brough...
Could a planet support both large mammalian megafauna and non-avian dinosaurs at the same time? My worry is that bigger mammals have progressively more trouble with dissipating body heat, whereas ...
In my world, physics works exactly like on Earth, except that there is a narrow, 400 foot tall magical column sticking vertically out of the ground, which is magically always extremely cold -- I'm ...
A XX century researcher time traveled back into the prehistory. He is not in danger of death or anything, but he has only energy to attempt one jump. He must jump back during the sunrise either i...
A common, matter-efficient science-fiction habitat is a hollow cylinder or ring in space that is spun to simulate the pull of gravity on its interior surface. These habitats have been imagined as s...
Everybody has seen superpowers like superstrength, flying, and regeneration. While flying and superstrength are quite straightforward regarding the energy cost, regeneration is not. In this questi...
In a world set many years (At least a generation or two) after a near extinction level nuclear event, how could a recovering population set up a internet or internet like service? Key points I'm i...
What amount of energy would you need to expend to create an arm out of nothing but energy? Of course we have $E = m c^2$ telling us the energy any amount of mass represents. Given the average of a...
I want a planet that is twice the diameter of earth's but has very similar gravity, atmosphere, and day length. Would doubling the rotational speed of the planet meet these parameters without notab...
I've looked around the forum but didn't find an answer to this particular question. In short, what food could realistically be produced in a space station assuming current (or near future) technolo...
The last time I asked a worldbuilding extinction question, I asked on what sorts of factors would create an extinction event in which 96% of all terrestrial species and only 70% of marine species d...
I was on a beach recently and was contemplating what it would look like if Silicon just didn't bind oxygen very well/at all, perhaps similar to gold. I'm not sure if something else would take the ...
So the background is simple: in the modern day a CME (coronal mass ejection, a solar flare that has escaped the sun) hits the Earth and destroyed all the electrical equipment causing planes to cras...
Rockets consume a lot of fuel and carry not eough payload. To reduce the fuel needed, why not send it in the mesosphere? Imagine a big balloon, capable of carrying a small rocket to the mesosphere...
I want to put a circular city in geostationary orbit. The city will have a radius of 20Km. I was thinking of using quantum trapping/levitation to achieve this. Here's what quantum trapping is: ...
By Colonies 'in' the outer solar system I mean the various moons and space stations past the asteroid belt. Currently the Hegemony has established bio domes, mining stations, and a few large scale...
Pretend I'm writing a story about a world exactly like our own. Real world physics, no magic, modern technology. Suddenly an eccentric world leader comes up with the idea to replace the melting gl...
There's a Thylacine that's found in Tasmania, unfortunately they only found a single female specimen. It it possible to grow Thylacines artificially (say like in an artificial womb) of both male a...
Premise In this Earth-like world, a multi-billion dollar privately owned aerospace/defense corporation is devising a secret plan to manufacture a fleet of nano-bots. These nano-bot have swarm inte...
I'm working on a story involving first contact with an alien species that bases their space travel on directly manipulating gravity fields. My question is not about how that would work, but rather ...
