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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.

56
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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. ...
25
votes
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, ...
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 ...
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 ...
0
votes
2answers
795 views

How does a spacecraft attempt an intercept course with a hostile one realistically (Part II)?

Well, gentlemen. Here is Part II. We know what to do about the manoeuvre, but we need to know possible tactical options the two Task Groups would use. Background Now, as previously specified, we ...
35
votes
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 ...
7
votes
1answer
438 views

The limits of human biology: atmospheric tolerances (#1)

This is the first question in a series on the physical limits of the human body. The intent of this series is to, illustrate the upper and lower limits of human biology for the purpose of building ...
16
votes
10answers
5k views

Could humans alter the moon's orbit significantly with current technology?

A terrible virus has made most of the populations and government officials of the largest superpowers on Earth stark, raving mad, without depriving them of their intelligence. They have decided that ...
9
votes
4answers
2k views

Would the Hawking radiation from a small black hole make a feasible propulsion source?

I was wondering if a small black hole would make a feasible/possible propulsion source, and if so, how. Pros Black holes release Hawking radiation, would should be easy to direct in a certain ...
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 ...
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, ...
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 ...
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 ...
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 ...
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 ...
5
votes
5answers
1k views

Realism of Solid light?

In the game Portal, there are glowing light platforms. These platforms are (supposedly) made of solid, compressed light. How can these realistically be made?
14
votes
5answers
3k views

Is non-manmade pandemic a realistic threat to modern first world?

Inspired by this question, and my own answer to it: Avoiding galactic pandemics. World ending pandemics are a common disaster/after-the-end story trope, I'm trying to determine if plausible, and how ...
6
votes
2answers
889 views

How big can we make a telescope?

I've mentioned in earlier posts that it will be much cheaper to build immense space-based observatory instruments than to even come close to launching an interstellar expedition. There are several ...
7
votes
2answers
598 views

What is the sack-to-ship ratio?

In the world I'm building, the day lasts 9 of their years. This means that they are almost always on the move, living in blimp-like cities and houses. I've been designing these and I am having trouble ...
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 ...
15
votes
5answers
2k views

How to get rid of all the heat in my spaceship?

Spaceships are a peculiar thing. We've got them in all forms, sizes & colours. They run on nuclear fusion, creating loads of power driving all sorts of shenanigans... but they still generate lots ...
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 ...
11
votes
2answers
2k views

Fusion candle - getting Earth to Jupiter

In A World Out of Time, per Schlock Mercenary, Earth is moved to a new home by lighting a fusion candle. The fusion candle idea is discussed in the Schlock quote: Building a gas-giant colony ship ...
6
votes
9answers
662 views

Can people upload their consciousnesses to computers?

The idea of uploading one's personality and consciousness to a computer is a semi-common science fiction trope. It has been suggested as a way to essential immortality. In a story I'm working on, an ...
8
votes
2answers
1k views

Attenuation of a laser in space?

Given that a laser beam is made up of coherent light waves running in parallel in the same direction, and that space is not a complete vacuum (dust, radiation, electromagnetic forces etc.), what kind ...
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 ...
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 ...
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 ...
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 ...
15
votes
1answer
541 views

As we increase the size and mass of a world, at what point does it become impossible for a rocket to achieve an orbit or escape velocity?

Many authors describe worlds with higher gravity than our own, from whence super-muscular aliens originate. However, as we increased the size, mass and surface gravity of a world; there would be ...
13
votes
5answers
2k views

How to get across the galaxy moving slower than light - in a single lifetime?

All the recent talk on Worldbuilding about the vast energies available to higher-level Kardashev civilizations, the need for 50,000 year message-systems, and so on, got me thinking. With enough energy,...
20
votes
3answers
631 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?...
15
votes
3answers
783 views

How to “set” the lightsail?

Suppose a starship is being powered by a lasers beamed first from the departure star, and then from the destination which is a moving base. The ship is moving in the regime of 10–30% of light speed. ...
6
votes
1answer
2k views

If Earth's Core had ALL Of the Heavy Metals

Back home, Earth had gone through an impact-coalesce cycle only once. Since then, its core has been 84% iron, 6% nickel and the rest being labeled by The Encyclopedia of Earth: A Complete Visual ...
4
votes
3answers
500 views

At what distance from these planets should this moon be placed?

I have two earth clones, in essence, separated by 16550 miles (26350 kilometers). They are, of course, tidally locked, and orbit each other once every 24 hours. These planets orbit a sun identical to ...
5
votes
2answers
825 views

What if a traversable wormhole hits the earth?

So, I the question of what if a black hole hits the earth has been asked to death by various people, but what if the somewhat tamer wormhole hits the Earth? In particular, we'll say that one mouth is ...
8
votes
10answers
934 views

Where to place my space-station so it observes one full planetary revolution per 24 hours?

For a SciFi project I work on I have a space-station orbiting earth that uses an 8 hour 3 shift system for its staff. Each shift is assigned to one-third of the countries and organizations on earth - ...
2
votes
1answer
498 views

What is the Roche limit for these two planets? [duplicate]

I want may planets to be as close as possible, but I really don't want this to happen. So, both of these planets are earth-sized, and they have a moon orbiting the two. These planets are also tidally ...
1
vote
1answer
211 views

Can I use my earth-changing invention to hide in orbit?

I've built a device, it's capable of turning matter to energy and energy to matter with perfect efficiency, I've got the resources to build a space station in secrecy, and I want to get off the planet ...
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 ...
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....
16
votes
2answers
1k views

Starbuilding: What is lacking in the logic behind Cosmos 2 star system generation algorithm?

Preamble The Alternity Cosmos II is a complement to a dice role-playing game that uses heuristics based on hard-science to 'build' plausible star systems for the Alternity game: http://www....
11
votes
8answers
697 views

Smallest possible habitable planet? (also taking density into account)

I have seen a few similar questions but none seem to take the density of a planet into account. I'm creating a planet on which several small civilisations develop. The planet needs to have a few ...
13
votes
2answers
773 views

How can a Type II civilization influence accretion rates from a debris disk to a passing star?

This is supposed to be a test of the hard-science tag. All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Speculative or ...
10
votes
8answers
2k views

Low-tech inertial dampener options

As mentioned in this discussion: How to keep humans pilots instead of AI in sci-fi future? the ability to handle G forces is a limiting factor on what pilots can do. Some of my solutions to address ...
19
votes
4answers
672 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 ...
9
votes
2answers
279 views

Cosmic Background Radiation in the past

I have a story where a species of the very first (literally first) carbon-based humanoid life (surprise!) that happen to emerge roughly seven billion years ago (their home system were formed twelve ...
5
votes
3answers
536 views

Ideal size for a relativistic generation ship?

Assuming the ship has access to fusion power, a large volume of solar panels, and crude antimatter power generators (say maybe 1 gram a day per generator, or whatever is reasonable for technological ...
5
votes
1answer
199 views

What's the fastest a genetically or technologically enhanced human could regenerate?

After watching this brilliant video by Shoddycast about Stimpaks in the Fallout universe: https://m.youtube.com/watch?v=CLY-FMxsb2U I started to wonder. Just how many of science fiction's most ...