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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.

97
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10answers
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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 ...
77
votes
17answers
17k 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 ...
77
votes
16answers
10k 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 ...
60
votes
17answers
10k 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 ...
56
votes
15answers
10k 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. ...
54
votes
11answers
11k 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 ...
46
votes
31answers
10k 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 ...
46
votes
16answers
12k 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 ...
45
votes
4answers
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 ...
44
votes
6answers
9k 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 ...
39
votes
19answers
4k 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 ...
38
votes
10answers
9k 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 ...
37
votes
3answers
7k 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 ...
35
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5answers
7k 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 ...
35
votes
10answers
3k 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 ...
33
votes
7answers
15k 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 ...
31
votes
10answers
8k 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. ...
30
votes
24answers
4k 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 ...
30
votes
8answers
4k 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 ...
29
votes
19answers
5k 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. ...
29
votes
13answers
6k 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 ...
29
votes
5answers
3k views

Creating a realistic world(s) map - Stars

This question is a sort of follow-up to Samuel's previous world map question, Creating a realistic world(s) map - planetary systems. Lots of science fiction stories involve journeying to nearby stars....
27
votes
6answers
7k 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 ...
26
votes
9answers
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 ...
26
votes
10answers
3k 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 ...
25
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17answers
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 ...
25
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5answers
2k 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, ...
24
votes
5answers
1k 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, ...
24
votes
4answers
4k 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 ...
24
votes
6answers
1k 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 ...
23
votes
5answers
5k 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 ...
23
votes
3answers
2k 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, ...
23
votes
4answers
674 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 ...
22
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7answers
6k 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. ...
21
votes
11answers
5k views

Blind spot in the Solar System

An alien spaceship the size of an Empire State Building experiences a technical issues with its cloaking device, their duty technician needs 24 hours to repair and meanwhile the alien wants to avoid ...
21
votes
2answers
2k views

Creating a realistic world(s) map - planetary systems

Once the geography of the world is designed, it needs a planetary system to inhabit. But how should that solar system look? The only constraint is that the system needs the new world to be placed in a ...
20
votes
10answers
2k views

How large can a volcano be?

A key part of the plot in a story I'm working on revolves around the main region being on top of volcano that is set to erupt. The trouble is that the region in question in my setting is roughly the ...
20
votes
4answers
11k 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 ...
20
votes
1answer
1k views

Could a planet's Karman line hypothetically occur under a liquid surface?

The Karman Line is one of the most commonly-used definitions of the "edge of space". As an airplane flies higher in the atmosphere, the air gets thinner and thus the lift decreases. This can be ...
20
votes
3answers
2k 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 ...
20
votes
3answers
630 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?...
19
votes
4answers
671 views

Making doomsayers right - a moon(s), planet alignment that matters

Considering our topic challenge, and the fantastic eclipse last Sunday a question came to me. Could there be a stable (relatively speaking) planetary system where a(n) eclipse/alignment would ...
19
votes
5answers
4k views

Can free-space holograms exist?

Holograms are a real thing. But what science-fiction TV shows and movies call holograms are something different entirely. From a classical geometric optics standpoint, in order to create the ...
18
votes
4answers
1k views

What would the economic impact of the ability to transmute lead into gold?

Okay, my first trial run, How would humans and society react to a superhero existing and saving the earth?, of social sciences with hard-science is looking some what sickly at the moment (maybe ...
18
votes
1answer
3k 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 ...
18
votes
1answer
1k views

Making a planet habitable for humanoids: The star

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 ...
18
votes
1answer
1k views

Runaway Starship Ramps

This question is partially a spinoff of some points that came up in another recent question at Worldbuilding about interstellar space travel. Runaway Truck Ramps I live in Colorado, and on the ...
17
votes
4answers
2k views

How quickly can I form a mountain chain?

I'm designing a world, and I want it to have major geological changes over a short period of time. This includes continental drift, which I'm assuming should have some interesting results. In ...
17
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6answers
1k 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 ...
17
votes
2answers
431 views

The mass of an economically feasible non-microscopic traversable wormhole

Background In my hard sci-fi settings, there is an advanced Type II Civilization, that are progressing toward Type III Civilization (yes, I am referring to Kardashev Scale). They are sprawling across ...