Questions tagged [universe]

Concerning the entire universe, the universe itself, and alternate or parallel universes.

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96
votes
26answers
30k views

How to survive the heat death of the universe?

The eventual heat death of the universe is an awful time to be alive considering you wouldn't have long left after the last star finally fades away. In this scenario there is a small group of about a ...
58
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12answers
12k views

If every star in the universe except the Sun were destroyed, would we die?

If every star and planetary system and blackhole—all mass (not sure whether to include dark matter or not) except what directly makes up our solar system—in the Universe except the Sun were wiped from ...
53
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0answers
2k 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 ...
51
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10answers
4k views

Implications of Newtonian universe

I'd like to remove the speed of light limit from my world. However I don't want to just hand-wave the consequences. How should my universe look if: light travels at infinite speed, and so do gravity ...
47
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17answers
8k views

What if we lived near a boundary of the universe?

This answer and its follow-up discussion with the OP made me think, and boil it down to the essentials: We live in a universe that’s either infinite in spacial extent or unbounded, and wrap-around ...
42
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17answers
7k views

How to prove that the solar system isn't inside of a localized physics bubble? [closed]

So, let's say that somewere out past the Oort Cloud, physics just kind of... changes. For whatever reason. Maybe space is magic, or maybe we're just in a weird sort of localized physics bubble. The ...
31
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5answers
6k views

How to detect that the universe got mirrored?

This might be more fit in physicsSE, but since I don't even know if my premise is physically sound, I'll post it here. One day, something caused the universe to get mirrored, meaning a left-right ...
29
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14answers
6k views

The universe is in a long, slow decline to darkness (the stars are going out) - What can we do about it?

The universe is in a long, slow decline to darkness Sorry folks but it's true, read the article! Here's a much edited-down version: The universe is cooling down, its stars pumping out about half ...
29
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8answers
6k views

What does it actually mean to have two time dimensions?

The trivial answer is that it just means "you have two dimensions with inverted sign in your spacetime metric". But the perceptual result of that kind of choice doesn't actually look qualitatively ...
23
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4answers
2k views

A brief dip into the heat death of the universe

Setting: Modern Earth; technology no more advanced that what's reasonable within the next thirty years. Premise: A prehistoric (and broken) alien device is discovered on Earth, and researchers ...
22
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17answers
3k views

Lost in the multiverse: how to find home?

You have an individual who can travel backwards and forwards in time. They normally maintain an observer status but occasionally a butterfly is stepped on. Because, home is where the heart is, how ...
20
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8answers
4k views

Universe where mathematics is different

There are many ways to conceive of a universe where physical constants are different to our own; however, what would the universe be like if mathematics itself were different? For instance, what ...
19
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3answers
4k views

The One-Electron Universe postulate is true - what simple change can I make to change the whole universe?

The one-electron universe postulate, proposed by John Wheeler in a telephone call to Richard Feynman in the spring of 1940, hypothesises that all electrons and positrons are actually ...
18
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3answers
7k views

What would powers based on the four fundamental forces look like? [closed]

The four fundamental forces, those being Gravity, Electromagnetics, Strong Nuclear Force and Weak Nuclear force are said to be the forces that hold the universe together and so on. Based on that ...
18
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1answer
3k views

What would the Universe be like if gravity was slightly stronger?

As the title says, what would the universe be like if the gravitational force was 0.1% stronger but the other forces (strong and weak nuclear forces, electromagnetic force) stayed the same? Would the ...
15
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5answers
2k views

Physical laws for a matter-filled universe

The Setting: I have an idea for a universe that, in an inversion to our own, is filled for the most part with matter in solid, liquid, gaseous or plasma form, while vacuum and degenerate matter is ...
13
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10answers
4k views

How small can the universe be while still appearing infinite?

I'm working on a concept of universe creation. The best way to describe it in a sentence is the Judeo-Christian Creation Story but from God's point of view. My question is, staying as close to hard-...
10
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9answers
3k views

How to justify that people forgot the past and that they have neighbours?

Let's say that there are 2 countries with very different inhabitants. Country A has no idea that country B exists. Country B may or may not know about Country A. Country A is surrounded by large ...
10
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7answers
1k views

Is it possible to have the age of the universe be unknown?

I’m making a fictional galaxy, and I want the inhabitants of this galaxy to be unable to calculate the age of the universe, I want them to be unaware of how much has already happened. I’ve already ...
9
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9answers
6k views

What would shake a galaxy and what would shake the universe?

I'm trying to think of what kind of cosmic event would cause an explosion powerful enough to "shake" or disrupt the whole flow of a galaxy and on that same note what other kind of super cosmic event ...
9
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2answers
7k views

What would happen to the universe if gravity became slightly stronger? [duplicate]

Almost the same as my other question but it isn't about how the universe would form. What would happen if to the universe if someone changed the strength of gravity by say 2%?
9
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2answers
348 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 ...
9
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4answers
241 views

Could cosmic background radiation be used as a means of cataloging parallel universes?

In a situation where you have people traveling between parallel Earths, where they dropped in with little ability to tell which Earth they are on, could checking cosmic background radiation be a ...
9
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3answers
574 views

Repulsive Universe

Gravity in our universe is an attractive force between bodies with mass [citation needed]. This allows matter to coalesce and form all the large scale structures we observe - planets, stars, galaxies, ...
8
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4answers
589 views

Slowing the Heat Death of the Universe

I have an enormous civilization spanning a large amount of the universe. It is able to both travel and send information much faster than the speed of light without violating any laws of physics. ...
8
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7answers
302 views

Staggering “Now” Among Many World Multiverses?

Regarding the Many World Multiverse, everything I've been reading (and searched on SE) seems to assume that each (parallel) universe is, at this moment, the same age. For my story, I need this to not ...
8
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5answers
550 views

Liquid universe: The beginning

The current Underwater tag challenge gave me an idea: What if the whole universe were actually liquid? To elaborate: How can a liquid universe come to life? Ultimately, I want to have a universe ...
7
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4answers
3k views

What if Newton's 1st law of motion is modified?

Newton's first law of motion states An object remains with the same velocity, or position of rest unless an external force is exerted. What if we created a hypothetical universe where An ...
7
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2answers
285 views

Taming wormholes

An ancient civilization mapped wormholes when the universe was quite young and smaller. This allowed them to reach other galaxies (wormholes from our galaxy to others). They mapped it all. Humans ...
7
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4answers
579 views

Traveling Back in Time at the End of the Universe

Suppose humanity lives on for the next trillions upon trillions of years. One day we'll get to a point where no useful work can be done and hence no life can exist: the heat death of the universe. ...
7
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2answers
243 views

Cosmological consequences of a world with super-high refraction and atmosphere opaqueness

Disclaimer: the overall idea of the world as presented is basically lifted from Strugatsky Brothers "Inhabited Island". The details of the question are for a derivative work in that universe. Imagine ...
7
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2answers
179 views

Other universes in a broad sense [closed]

When speaking about other universes people usually consider altered physical laws, while leaving logic and other basic things unchanged. What if to consider other universes based not on different ...
6
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2answers
611 views

How close could a planet get to a super massive black hole before being destroyed

I wanted to create a scene where two god-like characters are talking or fighting on a planet or fragment of planet to which they've teleported that's about to be obliterated by a black hole. The ...
6
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5answers
266 views

How to reduce demagogues' influence on the universe literally shaped by people's beliefs?

The laws of the Universe are not set in stone. Impossible does not exist. Everything, absolutely everything, is possible given that enough people believe in it. Centuries ago magic was as real as ...
6
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5answers
751 views

How can civilizations develop if the day keeps repeating forever?

Set in 2015, a highly classified experiment goes awry and as a result the entire universe including non-observable and all multiverses are trapped in an infinite time loop whereby each cycle lasts 24 ...
6
votes
3answers
209 views

How Likely is a Planet Made Almost Entirely of Metals?

For this question, the word 'metals' does not refer to elements heavier than hydrogen and helium. It instead refers to metals as defined by the periodic table of elements. After researching the ...
6
votes
7answers
769 views

Parallel universe portals: an infinite hall of mirrors?

Parallel-Universe Portals A solid material has been discovered that, when shaped into a ring and activated (by lowering its temperature below some critical point, let's say), it forms a parallel ...
6
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3answers
491 views

Parallel universes, mirrored

My question regards mirroring, specifically what you would expect from a universe that was mirrored from the perspective of our own, regarding its interactions with our own. The mirroring works ...
6
votes
2answers
160 views

What’s the difference between inter-dimensional, inter-universal, and extra dimensional beings?

Recently, I’ve grown curious other universes and dimensions, and while looking around and reading about said things, I’ve come across the terms inter/ extra dimensions and universes. This got me ...
6
votes
3answers
326 views

What would it look like in the accretion disk of a feeding supermassive black hole?

I wanted two characters unaffected by the heat and gravity to be close to a super massive black hole within the accretion disk, at times moving in orbit and at times completely still. Stars and ...
6
votes
5answers
489 views

What physical constraints should a near omnipotent civilization consider when simulating a Universe?

Background The Foo are a universe spanning civilization ranking near IV on the Kardashev scale. As explained in this question, they have decided to devote their vast resources towards the ...
6
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2answers
538 views

How would a civilization similar to earth develop if there were no stars at night?

Stars and constellations have been for many civilizations,sources of wonder and mystery. We look at the stars so much, that we found patterns and shapes in the stars, and used them as guidance during ...
6
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4answers
1k views

Consequences of a two-dimensional universe on cells and life

Suppose you have a 2+1 dimensional universe where the physics of that universe (we'll assume that the physics causes something similar to chemistry and that there is no gravity, but there is special ...
5
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7answers
3k views

Travelling the multiverse by accident? [closed]

As you've probably guessed, I have no idea how multiverses and parallel universes, or space-time travel, etc work. I don't know how Physics or Mathematics explains alternate universes. But, they are ...
5
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5answers
1k views

Can you just wait out the heat death of the universe?

Okay, so the heat death of the universe is approaching. You can't stop it. You can't dodge it. What do you do? You wait it out. According to wikipedia, about $10^{{10}^{56}}$ years after the heat ...
5
votes
2answers
298 views

What would happen if the Earth passed through an interstellar dust cloud?

I understand an interstellar dust cloud as "an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the ...
5
votes
9answers
398 views

How can I create an infinite space bound by another infinite space (or contained within it)?

First let me preface by saying this question will be very math heavy, and might be as equally suited to math stack exchange as world building. For that I apologize, but since the reason for my ...
5
votes
2answers
341 views

A universe without light?

In the story Wang's Carpets (and part of the novel Diaspora), Greg Egan sketchily describes a high-dimensional universe which contains no analog for light, such that the aliens who inhabit this ...
5
votes
3answers
319 views

Could life in a planemo be sustained by cosmic background radiation?

I need to create a race that should be utterly older than humanity (and as such, much more powerful). My idea is to have that race originate from a rock planemo - a rogue planet, orbiting the center ...
5
votes
4answers
315 views

Considering life to be a matter modifier - what would be the final state?

Imagine every organism is a matter-modifying and sorting mechanism within a very large chaos. Organisms believe their purpose is to evolve by reproduction and they're able to not wipe themselves out ...