# Tag Info

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I don't think you would get a flash when it hit. You would get a small one that would be obscured by all the particles that it would throw up. You may crack the surface enouph to let out sub surface water and produce a ploom of "snow" but it would freeze again. The area it hit would be flash boiled and you would have multiple quakes. Some from the ...

5

At about 250 megatons, the resulting energy would be about 10 times greater than the Mt. Saint Helens Volcanic Eruption. This would be enough energy to launch a mass of debris equal to a large mountain into the air, and at only 0.126G, a significant portion of it would be able to exceed escape velocity flying off into space. Calisto has a very minimal ...

0

Big Rip In Progress Rather than the Big Crunch or a ultra-massive black-hole of some description.. Reality itself is tearing. The counterpart of the Big Crunch theory is that the universe just keeps expanding at the speed of light until it rips apart at the seams. This isn't the mainstream theory in reality, there's not much reason to think the universe can'...

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The mythogoly "Helios (also Helius) was the god of the Sun in Greek mythology. He was thought to ride a golden chariot which brought the Sun across the skies each day from the east (Ethiopia) to the west (Hesperides)" ~https://www.worldhistory.org/Helios/ Your earth-like civilization may have experienced certain geopolitics along the way (in ...

2

Authentic, high carbon steel armor could shatter if heated red hot and then rapidly quenched, then struck, as this would make it full-hard an untempered. But as said above, the heating process would kill the wearer. A fair amount of SCA/reenactment/sports armor is plastic. This can break if stuck harder than it was designed to take, if it's old and the ...

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If you want twilight everywhere, you would need a disk-shaped mega structure with a hole in the middle that the sun sits in. That way, it is always twilight (or sunrise?) everywhere on the disc.

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Your planet could become tidally locked to the sun! We always see the same side of the moon because it is tidally locked to the earth, so there's no reason why your planet couldn't become tidally locked to your star. Just looked into it as well, and apparently the earth could eventually become tidally locked to the sun, but it'll take a long time due to the ...

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Artificial mega-structures encasing the planet. This is just the initial display for an artificial sky on a giant shell around the planet with artificial lights on the inside as a preliminary step in turning the planet into an intergalactic spaceship. The sun will start "moving" again once the engineers are sure they've got the rest of the shell's ...

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So if the sun needs to set at twilight, it will only be twilight on a small sliver of the earth if it's round. On other parts it would be dark, and others it would be forever afternoon. The earth is actually rotating due to inertia of the planet when it was born 4.5 billion years ago. You can read that here. Another interesting fact is that the earth is ...

1

The sun is part of a binary system with a dark object of similar mass, such as a black hole. The planet orbits around the centre of mass of both the sun and the dark object. The sun and dark object are sufficiently close that their orbital period is similar to the planet's rotation period (i.e. the length of a day). As a consequence, the sun's apparent ...

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There are already some good answers here about how to get the sun to stop. I'd like to talk a moment about what the effects of that would be. Initially, huge gee forces Right when it stops, as @user535733's answer says, you've got huge inertia problems where anything not fixed to the Earth is suddenly moving at supersonic speeds. Great. But there are also ...

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"The fool on the hill sees the sun going down, And the eyes in his head see the world spinning round." The sun largely is motionless in the sky. The observer on earth is on a moving platform. The earth rotates on its axis once a day, and revolves around the sun once a year. But that's not what common sense tells people. They feel like the earth ...

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The sun just powered up a reactionless drive and is now circling the still rotating earth - but this doesn't work with known physics. Could perhaps be a flyby from a rogue black hole, but that wouldn't permanently fix the sun in position. The orbit is non-longer a circle. Winter is coming.

3

Some hyper-advanced race deployed a vast number of gravity projectors around the planet and used them to bring it to a stop--it's now tidally locked in that position. You'll need a vast number to make the field even enough you don't tear the world to pieces in the process and you'll have a big problem handling the energy involved without spilling enough to ...

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Giant mirrors in space. (Assuming you want a reasonably non-apocalyptic way of making "the Sun stand still", and a technological level within the current millennium) A large (sort of) statite is placed in the L1 Sun-Earth Lagrange point. Also, a Fresnel mirror is placed just beyond the Sun, focusing a stream of sunlight towards a third mirror in a ...

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Gravitational lensing. Unknown to humans, dark matter is a very real force in the universe, and a large amount is going through the solar system. This has set up an orbital circle around the earth and the sun. Dark matter doesn't impact matter but does impact light, and so the light of the sun is being focused along a particular track by the intense ...

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On Earth, the planet would need to suddenly stop spinning. At the equator, that's roughly 1000 mi/hr "just" to a dead stop. Woe betide the billions of people close enough to water to be drowned in the ensuing tsunamis. Not that most would notice, having already been pulped by buildings falling upon them or shredded by 1000-mile-an-hour winds. The ...

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As I understand it, either the planet's rotational velocity must match the planet's constant gravitational orbit (and the associated indirect rotation) around the sun, so that it always faces the sun at the same angle, or the planet is not moving nor rotating at all.

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I understand radio communication on Earth has effective range much longer than the distance to the horizon, because radio waves bounce off the ionosphere. Without that, is it strictly line of sight only, or are there other effects that enable communication over the horizon? This is rather well known, radio propagates effectively by ground waves for long and ...

2

Tropospheric ducting. This occurs at any moderately high frequencies (not so much in longer wave radio) and in visible light. The cause is to do with layers of different atmospheric density lying over each other such as happens in an inversion (AKA temperature inversion). It's familiar to most people as the kind of mirage that can occur on a road in the hot ...

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I understand that your question is for today's capabilities but a ship would travel for long distances needing to repair part and upgrade along the way. Even if a ship is limited to the knowledge and capabilities of those and the technology on the ship and limited by their slow speed of travel, information from other colonies is only limited by light speed, ...

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Nebulae contain incredible amounts of resources (they are, after all, the remnants of supernovae) although said resources are generally incredibly diffuse, e.g. a nebular cloud the size of the Earth would have a total mass of only a few kilograms. So they're probably not an efficient option, unless you're able to find the denser areas.

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Marines would be the immediate highest bidder for your hovertanks. Why bother with a dangerous docking maneuver or loading tanks onto a boat? Use the tank as a boat. This probably cause a lot of amphibious assault ships to be refitted for fast deployment and loading of hovertanks. A hovertank will have better agility than a traditional tank - able to turn ...

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While not fully related, I felt like adding what the GBE would be with such cubic planets. -G * ((Mshell * Minterior)/r) Which would, assuming r = a/2, change to: -G * Integral(Lower: 0, Limit: R) * ((2r)^3)*p)((24r)^2)*p)/r) which goes to: (4608Gr^5p^2)/(5) Plugging in for density: (72GM^2)/(5r) Joules of Gravitational Binding Energy. If one just uses ...

2

Goodbye Limbs, Hello Water ... though they may be back if the brain can handwave drug-production and has a good diet. You'll have to play with your parameters, but mushrooms be converted to a leather-like substance under the right circumstances. This is produced today and marketed as "vegan leather". Forming this into a glider, you might be able to ...

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Recycle For a growing civilization, you'll still need a net increase in total mass to keep things going, so this won't eliminate the need for mining. However, I'm sure there will be plenty of trash and other unused matter that can get thrown back into the machine. This answer is inspired by the 2-part "Year of Hell" episode from Star Trek Voyager, ...

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Well - if you really 'just' wanted matter, there's apparently hydrogen out in interstellar spaces. While its meant for reaction mass for a rocket, you could essentially use something like a bussard ramjet as a way to harvest it, and fusion to produce helium. I'll leave it to the reader to work out how to turn a healthy breakfast of the neutrons, electrons ...

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You're describing a variant of a TROPHY-like active defense system. If you have sci-fi tech, you could build a tank with panels containing extremely pressurized air sufficient to cause a blast wave when the panel is opened. When an onboard sensor suite detects an incoming missile, it estimates which panel will be hit and vent the panel just before impact, ...

5

Make it using lasers Just a couple of years ago, scientists discovered that an adequately powerful laser can be used to create matter out of a vacuum. If your advanced civilization has discovered some infinite or virtually infinite source of power, they may decide to simply fabricate new matter out of nothing. Although this technology technically exists ...

-3

Attach propulsion systems to asteroids and crash them on a planet or airless moon where traditional mining techniques can be used.

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You're dead anyway I was going to calculate the parachute area required for base jumping with that mass, but then it came to me that mycelium is not a proper fabric for this. So your best bet would be to mushify all soft tissue for cushion, but then you will have no circulation and as such will be brain dead for want of oxygen. I think the death by impact ...

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I've also seen fiction that 'mines' the dark-energy field, basically slowing down the universal expansion by an immeasurable amount. But at that point you might as well just say 'magic'.

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Create a pocket universe. (or just find one) Keep it contained yet accessible. Trigger a big bang and expend it enough to cool. Once cool enough matter will form. Extract the matter from that universe to the one you are in. Or, Mine the Past. (with a nod to the Strugatsky brothers) send pipelines and other implements into the past and get the goods before ...

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There's starlifting. Wikipedia, YouTube. Basically, the idea is that you get a large (humongous) magnet orbiting the star (or hovering over it artificially via solar wind sailing), with which you attract magnetically charged plasma of the star's surface (but a couple of other means are described at the respective links). You then collect the uplifted matter ...

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Atomic transmutation (a.k.a. alchemy) is a gestalt technology. It changes everything. Mining is the process of digging through masses of undesirable material to find the comparatively rare desirable materials. When any material can be transformed into any other material at an atomic level, the whole idea of mining flies out the window. Dr. Emmett Brown ...

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If there is a powerful and abundant enough energy source, there is always the option of converting energy into matter, remembering that $E=mc^2$. That would allow for creating directly any nucleon and from them any atom. However mind that only to create 1 gram of matter one would need $10^{15}$ J. That's why I started with "If there is a powerful and ...

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The biggest challenges to your idea are economic A specialized siege engine is going to be very expensive. Regardless of what technology it uses, the forces involved mean it will need several large, finely crafted parts made of strong materials. It will require skilled operators, who know how to use it without the forces tearing the machine apart. Such a ...

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You don't need to change anything in physics to have a runaway death of the universe scenario. You just need a strangelet to come into existence. A strangelet is a hypothetical particle consisting of a bound state of roughly equal numbers of up, down, and strange quarks. An equivalent description is that a strangelet is a small fragment of strange matter, ...

4

Big Rip is another good candidate. Dark energy is going to increase to the point that all matter in the universe is going to be ripped apart. Its downside is that if it's indeed going to happen, it will be billions or trillions of years in the future. But let's say we have strongly underestimated the dark energy. Let's say the dark energy is going to ...

8

An idea that gets tossed around a lot in this sort of scenario is false vacuum decay. Let's say we have a tiny ball on the end of an ideal spring, moving back and forth as a harmonic oscillator. The ball and spring have some amount of energy $E$, and knowing the value of $E$ tells us something about the dynamics of the system. There's a quantum analog to ...

3

Newton laws states that $F=m\cdot a$, where $m$ is the inertial mass and the proportionality factor between the applied force and the resulting acceleration. Therefore, to answer your question, if the inertial mass is changed by a factor $k$, the acceleration resulting from the same force will be changed by a factor $1/k$. You double the inertia? The ...

1

There are a lot of ways this could be no One thing about trying to enter a black hole is that the conditions just outside of the event horizon tend to be very hostile. With smaller black holes, the main problem is gravitational shear which makes it very unlikely for matter to survive entry into a black hole in any recognizable way. As any body made of ...

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Humidity. Humid air conducts electricity better than dry air. This is why static shocks are more problematic when humidity is low - humid air bleeds off the charge and prevents it from accumulating. Rather than plasma, the burst that "rapidly flooded the area" is water. I could imagine a spray of very fine droplets would greatly enhance detection ...

3

... uses naturally generated plasma bursts to enhance electrical currents of potential prey, in much the same way that an IR light can be used to increase visibility when using night vision goggles / scopes / etc. This won't work. IR light is reflected from objects, and will increase visibility if you're using IR vision systems (it doesn't do any good if ...

1

Light emitted by the person would be blue-shifted, but most light is going to be reflected light, and that wouldn't look any different to an outside observer. That's because that light would be red-shifted as it enters the bubble, and then blue-shifted back to the original frequency as it exits. Note though that reflection/absorption properties are likely to ...

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Yes, I think there would be a blue shift. Light emitted by the sped up person (or re-emitted after reflection) would have a higher frequency proportional to how much faster time is passing for them. Similarly they would see things as red-shifted, since the light arriving at them seems (to them) to have been emitted by things that have slower clocks/...

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You can make a scale experiment about this by filling a pot with water and a chicken egg. Climb on some stairs, turn the pot upside down as fast as you can. You now got a wet floor that also has egg yolk spread around. When water falls inside an atmosphere like the Earth's, the drag with air causes it to spread in droplets. If your hydromancer falls from ...

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The problem isn't speed, it is mass While spinning black holes and any spinning massive objects do drag space around it using the frame dragging effect, this is only noticible on very massive objects. A few kilograms won't produce a noticable effect. The Earth is much more massive even taking into account the difference in speed and the effect of that on the ...

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Per this source (https://phys.org/news/2019-09-fast-universe-mystery.html) the universe is expanding at between 70 and 90 km/s/megaparsec. With the middle value being 82. A rocket, even a perfect one, is limited by the rocket equation: dv = ve (mo/mf) Substitute c for ve, and dv of 0.3c has an mf / mo of 74%. Just on the acceleration. Squared to include ...

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Adding to what M. A. Golding and GrumpyYoungMan said, there's reasonable reason to believe that we'll never even leave Earth, let alone colonize space. If you're talking about exploring the entire universe we could set up a sleeper ship with a theoretical total conversion rocket and just go in any one direction, but the thing about colonizing space (as well ...

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