Questions tagged [hard-science]

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19 answers
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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. ...
PyRulez's user avatar
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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. ...
JBH's user avatar
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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, ...
James's user avatar
  • 32.8k
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 ...
celtschk's user avatar
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0 votes
3 answers
1k 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 ...
Future Historian's user avatar
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 ...
HDE 226868's user avatar
  • 99.8k
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 ...
HDE 226868's user avatar
  • 99.8k
7 votes
2 answers
2k 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 ...
PyRulez's user avatar
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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 ...
L.Dutch's user avatar
  • 275k
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, ...
anon's user avatar
  • 11.2k
16 votes
10 answers
8k 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 ...
Fiksdal's user avatar
  • 2,103
12 votes
2 answers
4k 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 ...
Mark's user avatar
  • 978
6 votes
1 answer
3k 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 ...
JohnWDailey's user avatar
  • 14.5k
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 ...
James's user avatar
  • 32.8k
19 votes
5 answers
4k 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 ...
dot_Sp0T's user avatar
  • 12.1k
19 votes
1 answer
2k 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 ...
HDE 226868's user avatar
  • 99.8k
10 votes
4 answers
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 ...
PyRulez's user avatar
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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 ...
Varrick's user avatar
  • 3,683
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 ...
DoubleDouble's user avatar
  • 7,378
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 ...
jackwise's user avatar
  • 773
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 ...
Sheraff's user avatar
  • 12.4k
16 votes
5 answers
4k 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 ...
dsollen's user avatar
  • 33.4k
16 votes
4 answers
2k views

What is the theoretical maximum number of habitable planets in one solar system?

In the DC comic book universe, the Vega System is a solar system around the star Vega (Alpha Lyrae), which is depicted as having dozens of habitable planets. While it seems to be an implausibly large ...
nick012000's user avatar
  • 5,266
8 votes
1 answer
753 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 ...
James's user avatar
  • 32.8k
7 votes
2 answers
761 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 ...
TrEs-2b's user avatar
  • 56.1k
6 votes
2 answers
1k 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 ...
JDługosz's user avatar
  • 69.2k
5 votes
5 answers
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?
dsfisher's user avatar
1 vote
3 answers
624 views

How to calculate the time on planet B for an event that happened on planet A?

We have had a number of "universal time" questions on this site — basically the various OPs have been looking for a way to establish a single time reference for the galaxy. I believe that's ...
JBH's user avatar
  • 116k
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 ...
Skye's user avatar
  • 10.2k
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 ...
Nathan Ringo's user avatar
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 ...
Tristan Klassen's user avatar
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 ...
hexpallett's user avatar
20 votes
1 answer
3k views

How does one calculate the tidal heating of a satellite?

I've been searching for hours, and most formulas I can find use complex/imaginary numbers or variables that I don't know or can't find out (such as the imaginary part of the planet's love number, ...
Alexader Ferguson's user avatar
20 votes
2 answers
5k views

Creating a realistic world(s) map - planetary systems

This Query is part of the Worldbuilding Resources Article. Once the geography of the world is designed, it needs a planetary system to inhabit. But how should that solar system look? The only ...
Samuel's user avatar
  • 48.5k
17 votes
1 answer
924 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 ...
Monty Wild's user avatar
  • 55.5k
15 votes
3 answers
918 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. ...
JDługosz's user avatar
  • 69.2k
10 votes
12 answers
1k 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 ...
HDE 226868's user avatar
  • 99.8k
8 votes
2 answers
3k 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 ...
Smoj's user avatar
  • 963
7 votes
2 answers
251 views

Help cooling living H$_2$ fueled pulse jet engine

A squid-like organism uses gravity powered flight but relies on jet propulsion for launch, pouncing, and evasive tactics. It’s aerodynamically based on the way a true squid flies however it has ...
Vogon Poet's user avatar
  • 8,159
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 ...
HDE 226868's user avatar
  • 99.8k
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 ...
Samuel's user avatar
  • 48.5k
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 ...
HDE 226868's user avatar
  • 99.8k
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 ...
Feaurie Vladskovitz's user avatar
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, ...
Henry Taylor's user avatar
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?...
JDługosz's user avatar
  • 69.2k
13 votes
3 answers
567 views

How far from the Sun could we detect an alien spacecraft similar to the Voyagers?

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 from ...
user's user avatar
  • 28.9k
13 votes
5 answers
3k 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,...
Serban Tanasa's user avatar
12 votes
8 answers
2k 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 ...
user avatar
9 votes
3 answers
1k views

A planet ringed by stars

Suppose there was a ternary system where the stars are effectively identical in mass, luminosity, radius, etc. These three stars circle a central point rather than two orbiting a larger third. At this ...
Frostfyre's user avatar
  • 25.2k
8 votes
2 answers
345 views

Tolerable range of surface gravities for interplanetary colonists?

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 ...
Arkenstein XII's user avatar

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