Questions tagged [science-based]

For questions that require answers based on hard science, not magic or pseudo-science, but do not require scientific citations. Contrast with the hard-science and reality-check tags. Do not use this tag as the only tag on a question.

Filter by
Sorted by
Tagged with
174
votes
18answers
66k views

How could dragons be explained without magic?

Dragons are a grand classic of fantasy. For this question, let's assume we're talking about the following stereotype: hatches from an ostrich-sized egg and can grow to mountain size if nothing limits ...
172
votes
19answers
30k views

Russian Dolls - How do they reproduce?

Warning picture showing dissected Russian Doll My theory I believe that Russian Dolls reproduce asexually. They are born pregnant. At the time of birth, the outer doll dies. What is now the outer ...
137
votes
39answers
32k views

What single change would have given the best chance for the Axis to win World War 2?

A common topic in alternate history fiction works is the question what would have happened if a major war had been won by the other side. These usually focus on the events after the war, and the ...
134
votes
11answers
25k views

Everything alive in the world dies this instant. Without bacteria to decompose anything, what happens to the remains? What does this look like?

So when I say everything, I mean everything. Humans, animals, plants, fungi, bacteria, all dead. If the bacteria and other detritovores and decomposers can't decompose anything since they themselves ...
127
votes
23answers
25k views

What could people notice about someone who is two times as dense as a regular person?

I've got a group of magical people living mostly incognito in an ancient society. They look and act exactly the same as regular people, but they are really magicians, and a side effect of having those ...
127
votes
11answers
23k views

How would I know if I were a 1 mm tall robot?

In the 1955 science fiction short story, The Tunnel under the World How would I know if my consciousness had been uploaded into a miniature robot living in a replica town? What would be the most ...
121
votes
14answers
18k views

How can I ensure my Evil Tower is always stormy?

It's been a good year for me as an Evil Overlord. Lots of princess kidnapping turned into sizable ransoms, several of my Doomsday Devices were sold for high prices at auction, and my Minions have been ...
120
votes
35answers
24k views

Why would giant mechs use melee weapons?

Mechs are really just giant usually bipedal walking tin cans with their human pilot inside. I mean, shoot the legs and they can't move much anymore. Not really realistic. Regardless, in a futuristic ...
119
votes
9answers
35k views

Releasing a T-Rex into a modern ecosystem wouldn't be that bad, right?

T-Rex Forever LLC has a mating pair of Tyrannosaurus rex. They're a bit shady on how they got them, time travel, cloning...they won't say. Third-party biologists and paleontologists have examined ...
117
votes
18answers
33k views

Could a planet made completely of water exist?

In the Star Trek: Voyager episode "Thirty Days", there was a planet made completely out of water, which is the inspiration for this question. However, that planet was held together by an artificial ...
107
votes
11answers
18k views

Could a Dwarven Civilization Exist?

Could a Dwarven society as described by Tolkien mythology actually work? Dwarves for the purposes of this question are short, stout, bearded men and women who live primarily underground. They have a ...
106
votes
18answers
21k views

What would make scientists realize they were on a flat world?

Scenario: While poking around in an alien ruin, scientists discover a gateway which offers instant transportation to an Earth-like world. The Observed World: The gateway leads to an area that is ...
104
votes
11answers
23k views

This sword is forged from meteorite iron - but how is that any good?

You know the common trope in fantasy. Meteorite iron is amazing. My armor is made of sky iron, made for me. A bear's armor is his soul, just as your daemon is your soul. You might as well take him ...
102
votes
28answers
26k views

How fast can I flood the Netherlands entirely and permanently?

I want the Netherlands to be flooded entirely, and I want the event to be of such a scale that it goes faster than hydroengineering can keep up with. This will mean that I need a sea level rise of ...
101
votes
25answers
19k views

How to build a trap to last the ages?

While considering Ancient Light Trigger Mechanism, it occurred to me that any ancient trap mechanism is unlikely to work very long without regular maintenance. It seems far too easy for dust to clog ...
101
votes
24answers
16k views

If our universe was a simulation, what could a bug look like?

Let's assume, without revoking any of today's science, that the world is a simulation. What would a bug look like? I'm assuming that "the eiffel tower suddenly being bent at 45°" is rather unlikely, ...
97
votes
26answers
27k views

Would intelligent life evolve any other body plan than humanoid?

Disclaimer: This question uses some liberal wording to get key ideas across. It's not meant to be academically rigorous, so please try to focus on the ideas and not the exact definitions of the terms ...
96
votes
6answers
22k views

Would a Moon made of water pose a threat to Earth during eclipses?

Is a moon made entirely of water possible? Could a planet made completely of water exist? I was inspired by the above questions to ask the following: Assume that our current Moon is replaced ...
91
votes
26answers
26k views

A poison that only works if you know it is there

In the book He Drank and Saw the Spider, a poison is talked about in a metaphorical way: A person can be poisoned by putting a specific kind of spider into their cup, but the poison only works if you ...
91
votes
19answers
32k views

Why would vampires be incapable of entering a non-vampire human’s house uninvited?

I'm looking for a scientific explanation as to why vampires would be incapable of entering a human's house uninvited. There have been many terrific scientific explanations for some of the most ...
89
votes
17answers
14k views

Are there logical gaps in the periodic table in which you could insert a new mystery element for use as a fuel?

As in the title. We have the modern periodic table: In a potential near (or far) future setting humanity discovers a new element which serves as the basis for a cleaner, higher energy density fuel ...
89
votes
13answers
17k views

A mosque on Mars?

Premise Mars has been terraformed and has seen its first few stages of large-scale colonization. The colonists are middle to upper class Earthlings. Earth is not a dystopian planet per se, but Mars ...
87
votes
13answers
23k views

Lembas bread (2000 Calories per bite)

In the lord of rings the elves invented an incredibly nutritious bread/biscuit, as Legolas clearly says only a small bite is just enough to satisfy the needs of an adult man for 1 day. An adult ...
87
votes
14answers
9k views

Is there a scientific explanation as to why aliens should look similar to us?

In almost all science-fiction stories that include alien races, said aliens are similar to humans in many ways: bipedal (and often humanoid), communicate with sounds coming out of a mouth, orient in ...
82
votes
32answers
14k views

Conquering a Metropolis with near-zero own casualties

You have a trillion dollar/year military budget. You can buy all the toys (that are physically and financially possible to build with current technology). You can hire the manpower, command the ...
82
votes
11answers
15k views

Is it worth sending a manned mission to a black hole?

Suppose we detect a stellar black hole passing near the Solar system, and we have technology and time to send a manned mission to study it. Are there any experiments or observations that would help ...
80
votes
19answers
24k views

Humans can now run 40 mph. How do I keep the stupid people alive?

Let's assume that humans can now run 40 mph and the human body can handle it. I know and understand that this is not feasible, but let's just play pretend. Naturally people would have all kinds of fun,...
79
votes
16answers
19k views

Could astronauts find their bearings in the Universe after being transported 6 gigalightyears from Earth?

In my world, humanity reaches their new home among the stars by way of a portal that pops into the solar system one day. This portal instantaneously transports those who enter to a place that is ...
78
votes
7answers
13k views

How to protect shops in the medieval era against thievery?

While coming up with a medieval era world, I suddenly realized that there was pretty much no defense against thievery except for patrolling city guards which to be honest probably isn't very effective....
77
votes
7answers
11k views

Spiders In Space: How to design a space suit for an arachnid?

In my stellar empire, the sapient life of the home world are arachnids. Due to an oxygen-heavy world with certain evolutionary characteristics, spider-like beings developed intelligence and formed ...
71
votes
11answers
10k views

How can powerful telekinesis avoid violating Newton's 3rd Law?

Characters with powerful telekinesis are portrayed as being able to exert a superhuman force using only their minds. For example, they can throw a car. Based on what I remember from high school ...
71
votes
18answers
11k views

How do I make an alien technology feel alien?

In a lot of science fiction series, such as Halo, Mass Effect and Gears of War, they show alien technology that is flatly human with a few added-on bells and whistles. It lacks the awe or feel of ...
71
votes
20answers
6k views

Is it physically possible for a planet to have seasons of different lengths?

Those of you who have read Game Of Thrones will know that in the GOT world seasons do not have a fixed duration, e.g., a winter might last three times longer than the previous one. I find most ...
71
votes
11answers
59k views

How many people can you feed per square-kilometer of farmland?

Questions about how to feed a large population keep popping up on this website quite frequently. One obvious option is farming. But how many people can you feed per square-kilometer of farmland? ...
71
votes
14answers
8k views

How to harness Jupiter's gravitational energy?

I am currently orbiting Jupiter, the rent is pretty cheap and the view is magnificent. However, my former electricity provider refuses to connect me to earth's grid for petty reasons like "are you ...
70
votes
15answers
11k views

How can an unimaginably huge life form reliably communicate with mortals?

The Starmakers are vast. Stars are their seeds, supernovae their hatching. Unimaginable millennia pass before they even begin to blink at their neighbours, and they do not die, merely pass along their ...
70
votes
17answers
18k views

How can I move a planet?

There are a lot of answers on Worldbuilding about how to destroy planets - just as an example - and they seem to be the method of choice for many people intent on destroying the world. My objection to ...
69
votes
17answers
12k views

How could a natural road form across a sea?

BACKGROUND I'd like my earth-like world to have a naturally formed narrow strip of land that bridges a major sea. Now, before anyone rushes off to comment about island chains and land bridges, I'll ...
68
votes
34answers
21k views

What (modern) weapons could be used to destroy skeletal enemies as completely as possible?

As per the cliché, after getting hit by a truck, our protagonist finds herself in a 'swords and sorcery' fantasy world. Also as per the cliché, she is granted an overpowered ability to make her new ...
68
votes
18answers
12k views

Mineral that explodes when cooling down

While playing old games, I encountered a friend I knew from SciFi series and games alike, the Merculite missile. While thinking about what Merculite might actually be (and linking it to a mineral from ...
68
votes
6answers
11k views

Would earthlike planets in other solar systems have well-known Earth gemstones such as rubies, emeralds and sapphires?

I'm currently working on a conworld that has never had any contact with Earth, and I'd like to create words for iconic gemstones, such as rubies, emeralds and sapphires. However, I can't help but ...
67
votes
11answers
11k views

Let's weaponize jellyfish

Jellyfish are... weird. They're clear, slimy, and can sting after death. Sounds perfect for experimentation, so lets weaponize them! Consider a hypothetical world where jellyfish are extremely common ...
67
votes
12answers
16k views

Could a disaster kill all (human) life on Earth but leave astronauts in low orbit alive long enough to return?

There are plenty of threats out there that could terminate all life on our little planet in varying amounts of time (Solar flares, meteors and supernovas to name a few). Are there any disasters that ...
66
votes
22answers
12k views

What single change would have given the best chance for the Allies to win the Battle of France in early WWII

The obvious WWII alternate history question is how could the Axis have won. Let's try something different this time. The Battle of France was a big gamble for the Third Reich. They sent more or less ...
65
votes
24answers
9k views

The opposite to Worldbuilding: World Destruction

I am looking at different ways to destroy a planet. I am assuming the planet is of a similar size and composition to the Earth just to keep things simple. I am starting at boiling the atmosphere to ...
65
votes
4answers
7k views

Can you simply scale up animals?

There have been a number of questions focusing on mythical creatures where the logical approach to answering has been to scale up an existing animal. For example dragon's wings can be extrapolated ...
64
votes
14answers
9k views

How can I hide my island?

I'm a supervillain. I have no name, but you can rest assured my intentions are dubious and always result in general harm. My biggest problem these days are these pesky superheroes keep finding my ...
64
votes
22answers
10k views

Mosquito Armageddon

I'm going camping in two weeks and I really don't want to get bit up by mosquitoes. So I want to figure out a way to commit total genocide of all mosquitoes in at least a 20 mile (32 KM) area around ...
62
votes
14answers
12k views

What is the minimum radius of a circular corridor for the walls to appear straight?

Where am I? It is so dark around here... Hopefully I have a torch. It looks like I am in a very long corridor. Time passes What? No this couldn't be! I walked straight in front of me during ...
62
votes
9answers
14k views

A 40km diameter alien saucer is floating 2km above the ocean for a long time. What are the effects on the sea ecosytem below?

Twenty years ago, a 40km diameter alien saucer came to Earth, and stopped 2km above the Atlantic ocean, somewhere near the midpoint between Casablanca, Morroco and Natal, Brazil but over international ...