Questions tagged [hard-science]
REVIEW THE WIKI BEFORE USING THIS TAG! For questions that require unequivocal proof that answers are correct through the use of equations, empirical evidence, scientific papers, etc. Compare to: science-fiction, science-based and internal-consistency. This tag may not be used alone. This tag may not be used with the science-fiction, science-based, or internal-consistency tags. Flag your question for moderator attention once posted.
984
questions
112
votes
11
answers
12k
views
Would planets be cubic in my "cuboverse"?
Summary
The main idea behind the "cuboverse" is that spacetime distances are measured by (something close to) the sup norm or infinity norm. Under this norm, spheres (the set of points at a fixed ...
- 1,516
88
votes
2
answers
3k
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 ...
- 99.8k
86
votes
19
answers
25k
views
Would a 'World Tree' be feasible in real life?
A livescience.com article claims that trees can reach a theoretical height of 400 to 426 feet (122 to 130m). This is due to the tree being unable to carry water up to the top at that certain point due ...
- 10.2k
83
votes
16
answers
13k
views
Can stars that are not powered by nuclear fusion exist?
Stars generate their energy by fusing lighter elements into heavier elements. The most common reaction in Sun-like stars is the conversion of hydrogen to helium via the proton-proton chain, but ...
- 99.8k
80
votes
19
answers
16k
views
Stealth in Space: How realistic is it?
This has been considered other places on the net, but I thought it would be good for the hard-science challenge, since it is often an example of the subtle difference between soft and hard science.
...
- 12.6k
68
votes
21
answers
21k
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 impossible. ...
- 116k
62
votes
17
answers
12k
views
What would it take to build a ship capable of crossing the Pacific?
In my story, I have a small extended family of 30 to 40 individuals ranging in age from 0 to 50 who are on the run from Chinese and Japanese forces in 1400AD. No place in Asia is safe for them. By a ...
- 52.7k
57
votes
11
answers
12k
views
How would people conceivably escape a planet too large for chemical rockets?
I was reading this article from NASA about chemical rockets and they argue that, with a planet 50% larger than the Earth (assuming similar density, about 1.5G surface gravity), it would be impossible ...
- 4,768
52
votes
7
answers
11k
views
Can I use a trebuchet to launch satellites into space from a lunar colony?
I've got a lunar colony that struggles to obtain resources, so they're looking for ways to launch satellites into orbit without using up a bunch of rocket fuel.
One plucky engineer has suggested ...
- 12.1k
51
votes
31
answers
11k
views
What's the most efficient way to destroy civilization from orbit?
What's the easiest way for your stereotypical aliens to destroy civilization from orbit? I'm taking "destroy civilization" to mean the destruction of all large-scale forms of governance, but bonus ...
- 695
51
votes
20
answers
12k
views
How can a person Insulate copper wire in a medieval world?
Time traveler here, stranded in the year of 1019 AD, medieval ages. Location: europe. While I can still access and post on web forums because my temporal transmitter has a 1Ky range, I have a broken ...
- 14.3k
50
votes
4
answers
6k
views
Moons of Moons of Moons
My question is simple: How many nested moons are physically possible?
If our moon had a moon, that would be a nesting of 1.
I'm assuming it's easily possible for a really big moon to be orbiting a ...
- 3,683
47
votes
16
answers
14k
views
What single element could destroy the world?
What single chemical element (get out your periodic tables) could most efficiently destroy all life on the planet.
Restrictions:
Natural elements only, and no anti-matter...nice try.
Looking for the ...
- 32.8k
45
votes
11
answers
9k
views
Can Cloud Nine be built?
Cloud Nine is the name given by Buckminster Fuller to his proposed tensegrity sphere airborne habitats. The principle is simple and the physics seem to be sound.
For a sphere, as its radius is ...
- 48.5k
40
votes
18
answers
5k
views
With current technology, what would be the best way to store energy for future generations?
Let's say that the world has successfully converted and only depends on renewable resources for our home energy needs. In fact, we have a massive surplus - currently in the form of raw electricity ...
- 7,378
40
votes
5
answers
10k
views
Can a planet survive a supernova?
The Sun has nowhere near enough mass to enter the branch of stellar evolution that would lead to a supernova, fortunately for us. However, there are planets that orbit stars that are destined to go ...
- 99.8k
39
votes
4
answers
11k
views
Would EMP From a Nuke Stall a car?
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 ...
- 21k
38
votes
10
answers
10k
views
Create "gold" from lead (or other substances)
I am writing a setting for a role-playing game. In it an alchemist has finally found a way to create gold from lesser metals.
Like his former historical models the alchemist is so jubilant over his ...
- 14.7k
38
votes
7
answers
4k
views
How do ballistic trajectories work in a rotating cylinder world?
For the sake of fixing some image in your mind, imagine you want to practice some sport in a rotating cylinder world: whether it be launching a javelin, strike a tee at the golf club or scoring a 3 ...
- 275k
36
votes
7
answers
29k
views
Could a large bird be used as transportation?
Sometimes I reminisce about the giant eagles from The Lord of the Rings and two things come to mind:
Boy, I wish I could have my own giant eagle!
Could a bird even carry something that heavy on its ...
- 773
34
votes
8
answers
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 ...
- 44.7k
32
votes
24
answers
5k
views
Close Quarters Combat... In Space
A simple enough question, but one that Grimmsdottir and I agonized over.
Basically, what would enable close-ranged fighting between space fleets/ships? We both agreed that having gargantuan ships ...
- 5,976
32
votes
5
answers
8k
views
Creating a realistic world(s) map - Stars
This Query is part of the Worldbuilding Resources Article.
This question is a sort of follow-up to Samuel's previous world map question, Creating a realistic world(s) map - planetary systems.
Lots ...
- 99.8k
31
votes
10
answers
9k
views
In theory, could all mammals be wiped out by a single pathogen?
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.
...
- 49.3k
31
votes
9
answers
6k
views
How useful would a hydroelectric power plant be in the post-apocalypse world?
The details don't matter, just that a large fraction of people have died (let's say 90%) and society has completely collapsed. It's only a year or two later, and people have started to gather ...
- 3,402
30
votes
8
answers
5k
views
How far away could Earth detect a projectile travelling at relativistic speeds?
Suppose our alien neighbors woke up on the wrong side of the bed and decided humans would be less annoying if their home planet was hit with a giant artillery shell travelling at half the speed of ...
- 565
30
votes
14
answers
7k
views
Can a planet have a day that's always longer than night?
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 course ...
- 5,519
30
votes
10
answers
4k
views
How could humans recognize another species as sentient / intelligent?
There is this fantasy in fiction that humans meet another species and figure out that it's intelligent. This usually happens with dragons, dolphins, aliens, collectively intelligent plancton...
But ...
- 12.4k
29
votes
19
answers
6k
views
Design a non-computerized biometric door
Nowdays we have biometric doors that can scan your eye, palm, fingerprint, ear, etc, etc...
But all of them rely on electronic readers and computers to match the sample against the stored pattern.
...
- 14.3k
29
votes
5
answers
9k
views
Can two moons have intersecting orbits yet be guaranteed not to collide?
Working on a D&D campaign. As a physics nerd, I'd like the orbital mechanics of the planet, its sun, and its moons, to follow standard Newtonian/Keplerian mechanics. I'm trying to come up with ...
- 495
29
votes
6
answers
8k
views
Would one atom of antimatter be lethal if annihilated inside the brain?
I am dealing with a dystopian story that tries to come up with some kind of total surveillence or control from higher authorities.
The authorities threaten to kill those who disobey them by simply ...
- 509
29
votes
6
answers
4k
views
Plausible biological alternative for normal photosynthesis
People have been trying to imagine elaborate alien biologically possible ecosystems for a while. A lot of people seem to both want but ignore one of those fundamental aspects of our own ecosystem, ...
- 11.2k
28
votes
12
answers
3k
views
How can spacecraft manufactured on the moon be powered?
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 ...
user42528
27
votes
8
answers
8k
views
What elements would be created in a star composed entirely of gold?
I'm working with the idea of creating a sun made out of pure gold. Of course, this would be completely man-made. Why would anyone want to do this? Because I want a cool concept like that in my story! :...
- 6,232
27
votes
5
answers
3k
views
Can you add a mini moon to Earth?
So we have had multiple questions on having multiple moons and this is another. I did check and didn't find questions that covered this specific setup.
I have an earth-like world I am working on, ...
- 32.8k
27
votes
9
answers
3k
views
How would characters find out they were living in a rotating habitat with only medieval tech?
Three natives who study their version of science on the surface of a large rotating habitat located in a cylindrical shape in the space between our solar system and Alpha Centauri, are trying to ...
user44929
25
votes
17
answers
7k
views
Need a way for Earth not to detect an extrasolar civilization that has radio
The exposition is that a civilization exists about 200 light years from earth and has been capable of radio communication for several thousands of years. They are not trying to hide from detection but ...
- 283
25
votes
9
answers
7k
views
Would an antimatter bullet fired from a sniper rifle even reach its target?
Let's say our villain fires an antimatter rifle from behind a magnetic field over a km from the target. The bullet is traveling over 1000 meters per second. If it reaches its target, the 13 gram ...
- 3,878
25
votes
4
answers
5k
views
Could a human baby develop and grow into an adult under constant 3-4G?
Would that even be possible? Will the bones deform during early infancy? Will the cartilages between joints wear off faster? Will internal organs collapse under their own weight? I have no ...
- 390
25
votes
1
answer
5k
views
How to make a flying human
We are in a future where genetics has advanced to a point where arbitrary modifications can be done to living beings. Now a geneticist wants to make a flying human. That is, he wants to modify a human ...
- 31.4k
24
votes
5
answers
6k
views
The polar ice caps are melting. Can I replace them with icebergs made of pykrete?
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 ...
- 1,709
24
votes
6
answers
2k
views
Close the door on your way out - Life lit by a blue dwarf star
I'm seeking a hard science setting for a piece of xenofiction with a decidedly non-sciencey feel. That said, there is no magic or magic technology.
The idea is as follows:
A red dwarf star has a ...
- 4,198
23
votes
7
answers
7k
views
How big can a moon be where you can physically jump out of its orbit, to its planet?
So, imagine a team of space marines, fighting some sort of space bug zombies on a planet's moon. Things are going pretty bad for them, and the last surviving protagonists are running for their lives. ...
- 20k
23
votes
5
answers
16k
views
Could a Tank Survive a Nuclear Blast?
In the red corner, a top of the line Main Battle Tank, you can have your pick, but let's say a tricked out M-1A2 'Abrams' with a full Nuclear-Bio-Chem Protection kit.
In the blue corner, a Nuclear ...
- 59.9k
23
votes
3
answers
3k
views
How big a black hole is needed for this story?
The story begins in classic disaster film style. A small rogue black hole is approaching our Solar System. It isn’t going to get close enough to destroy everything, but it will agitate our Sun, ...
- 69k
23
votes
6
answers
2k
views
Replicating the biblical flood
The Biblical story of the Flood describes how over a period of 40 days the earth is flooded so that the peak of the highest mountain is 15 cubits/22.5ft/6.858m below the new mean sea level. The flood ...
- 55.5k
23
votes
4
answers
1k
views
Could Earth and the Moon be the same size?
Many questions on this site hypothesize about two planets in close orbit of each other, each developing their own civilizations. How feasible is that?
Some 4.5 billion years ago Theia, a planetary ...
- 85.1k
23
votes
3
answers
978
views
Circulation patterns on a tidally-locked binary planet
A targeted hard-science spin-off from this question:
In a tidally-locked planet that rotates about a barycentric point that’s located outside of its own sphere, what would the coriolis forces be like?...
- 69.2k
22
votes
3
answers
3k
views
Making a planet habitable for humanoids: The planet
The question:
What characteristics are necessary for a planet to be habitable for humans? What should the generic star and planet be like?
The life forms are human, so they
Need to have access to ...
- 99.8k
21
votes
18
answers
3k
views
Antiballast for flying ship
Your miners find some strange stones - they float to the ceiling of mines.
With those stones you can easily build an airship - just fill a sleek wooden hull with them and give the rowers some wing-...
- 4,157