# Tag Info

66

Indoor skydiving Indoor skydiving simulators are popular and not particularly difficult to build. A person who falls into a "bottomless pit" would feel like they're falling faster and faster, reaching terminal velocity. In reality, the person would stay suspended in one place, with wind tunnel supporting their weight. If there's total darkness in ...

58

Floating city. There is a lot of it, but the water is fine. Build on top of it. https://www.dezeen.com/2019/04/04/oceanix-city-floating-big-mit-united-nations/ Modular cities can be expanded as the population increases (a population boom in Japan is itself a pretty interesting concept!). They can be rearranged as "land' used change. Damaged modules ...

38

Draining a sea is not an easy job. The Dutch know something about it. And here you are not talking about a shallow sea, but of something with an average depth of 1300 m. Moreover you will have additional, non technical issues. This is the Sea of Japan As you can see it separates Japan from Russia, North and South Korea. If you have ever been in an apartment ...

38

We already have something very similar to that which has been proven to work: Ranked Choice Voting. Everyone chooses their candidates in order from most preferred to least preferred. In this system, the number of offices to be voted divided by the number of voters sets a threshold minimum. All rank 1 votes are tallied, if all top candidates meet the ...

37

Lighthouses don't necessarily mean "stay away". They can also mean "you are here". Your setup is fine if: theres lots of ship traffic within a few kilometers. or theres a hazard within a few kilometers. This could be a reef or sand bar out to sea, or dangerous rocks several kilometers up the beach. There are no other night landmarks ...

35

Normally, only the innermost kilogram of uranium in an implosion-type bomb actually undergoes fission (and only 0.6 to about 5g of mass are ultimately converted to energy - the sources don't agree on this), because the explosion itself vaporizes and blows apart the rest and the fission cannot proceed further. This, by the way, was the main limit to the size ...

28

Here is a nautical chart of a random bit of Scottish coast: You see all of those coloured arcs and circles? Every single one of those is a lighthouse or similar (there's also a bunch of smaller buoys with lights on marked - I make it 45 in total between the two categories). You'll also notice that none of those lighthouses have any wrecks at all marked near ...

27

You're going to lose the Moon. At the Moon's current distance, the Earth's gravity can only change its velocity by $0.002m/s^2$ The mentioned acceleration of about $0.25m/s^2$ dwarfs that, and if at any time during this acceleration, the Moon's relative velocity to Earth exceeds Earth escape velocity for its distance, Earth loses it. At a distance of 384,000 ...

22

Behold! The Engineering Caisson! I'll let you worry about the inconvenient details like the depth of the ocean, the amount of material you'd need to bring in, keeping surprised neighbors like Korea and China happy, and the usefulness of edible fish. You want to drain that sea! Let's do it! In geotechnical engineering, a caisson is a watertight retaining ...

20

"By their fruits will you know them" Wild mind controllers will grow in their powers and use them for their benefit, perhaps without even being aware of what they're doing. Lots of people stare at one another all the time, instinctively thinking things like "Come on, say yes" or "Sign the agreement, sign the agreement!" or "...

16

Don't drain it - displace it. Draining it will require sea walls to be built. Those sea walls would be susceptible to flooding during storms, and this region gets strong typhoons with insane storm surges, and with sea levels rising due to climate change building below sea level is not wise. So - raise the land up to above sea level using something your ...

16

This is how Australian voting effectively works in practice. Australia is officially "Ranked choice voting" - You order N candidates from 1 to N, however I can tell you from experience and anecdotally that Australians typically vote "for" and "against" first, and then fill in the blanks between. So for example, my recent voting ...

15

Life would exist right up to the end, in a sheltered place far from the surface. Although the surface of the Earth may have been stripped of its oceans, saturated with radiation from the sun, and now a windswept inhospitable desert, life is resilient, and our planet quite saturated with it. At this moment there is evidence that life exists 4.8km below the ...

15

You don't need to make sophisticated calculations to get the size of the shadow in this configuration. Australia is about 4500 km across from East to West and 3700 km from North to South. As compared to the 9 km on top of the Everest, the border effect can be neglected, and the size of the shadow is practically the size of the object producing it. For a ...

14

T = 0.0000000000 seconds : The Sphere appears. T + 0.0000000001 seconds: The Sphere disappears. some...minor... light flash may be observed shortly thereafter, as the planet is vaporized. Supporting numbers: sphere: 1000m diameter. Radius 500m volume 5.24e8 m3 total content = 5.24e14 cm3 Uranium-235: Density 19.1 grams/cm3 Molar mass 235.0 Molar volume 12....

13

Lighthouses are not cheap, quick, or easy to build or maintain. Because of this they are only likely to be situated where they're going to give the most benefit So what benefit does a lighthouse give? It's a big light, that can be seen at a great distance. You can (and usually do) also have shutters rotating around to make it appear to flash in different ...

13

The poor die The rich die The grass dies The bacteria dies everything dies. For starters, the air pressure in current seaside cities will drop down to 30% of current levels. The same as if they were suddenly transported to 9000m altitude, just above the peak of mount Everest. The oceans may only average 3.7km deep, but they cover a surface area 2.5 times as ...

12

Within a few minutes, when GPS goes out The Global Positioning System, and similar systems, such as the Russian GLONASS, rely on very precise measurements of the distance between a receiver and several satellites. The satellites are orbiting the Earth, but that doesn't mean that accelerations applied to Earth are applied to orbiting satellites. Unless the ...

11

We at MegaGeoCorp stand ready to offer you the sovereign solution to all your ocean draining problems! Now, it's true that draining a whole sea is a bit of a technical challenge, but really, the challenge is but one of scale. A little siphon pump can draw up water from a rain barrel very handily, for example. For this job, we just use bigger pumps! But that'...

11

Goodbye, moon! The moon's centripetal acceleration is always pointed at the earth, and has a value of just 0.0027 m/s^2. If you accelerate the earth in the opposite direction at 0.025g (0.245 m/s^2), the earth will move away from the moon with a net acceleration of 0.242 m/s^2. As the earth moves further away, the force of gravity lessens, resulting in a ...

10

Farewell Luna. But, there might be a way... I simulated the Sun-Earth-Moon system to determine the trajectories of Earth and moon. With your given acceleration $a=0.025g$ and $T_{accel}=12\ \text{hours}$, the Earth categorically, and quickly, leaves the moon behind. One parameter we have to play with is the angle of the relative position of the moon, $\phi$,...

9

So assuming we're starting with an atmosphere weighing (5E18 kg) of 21% oxygen (1E18 kg), and ending about 0.5% atmosphere (about 2E16) kg), and the oxygen cycle continues functioning minus anything living: At current air pressure, the lithosphere will absorb 6E11 kg of oxygen a year. Lightning also removes about 1E11 kg of oxygen a year by combining it ...

9

Evolution requires generations to pass before a change can be made and spread into the general population. The more complex the lifeform, the longer and more complex the lifecycle and the longer it will take to adapt. In a rapidly changing environment only simple life forms with rapid generations are likely to be able to adapt in the final years. The last ...

9

Depends on direction of thrust and relative position of bodies Firstly, the Earth-Moon system will definitely be disturbed. The most likely scenario is ejection of the moon, though collision is possible if you happen to... well, accelerate the Earth into the Moon. You are applying the force to Earth only, which means that you are disturbing the parent-...

9

Massive volcanic eruptions or a big enough asteroid impact can both lift enough dust in the high atmosphere to practically dim the sunlight. It happened during the year without a summer The year 1816 is known as the Year Without a Summer (also the Poverty Year and Eighteen Hundred and Froze To Death) because of severe climate abnormalities that caused ...

8

Depends what the country prioritizes Contemporary research ships come in all sizes. According to Wikipedia, many Liberty ships were converted for non-military duties after WWII, and Liberty ships were fairly big and clunky. However, those were cargo ships (as pointed out in comments) and I can't find large-scale examples of combat ships being converted to ...

8

Plausible Methane rising from undersea vents was proposed as a method behind the bermuda triangle making ships disappear. The Guardian certainly believe it to be plausible: ... And ships certainly could sink suddenly if the water beneath them turned to foam, which these craters – measuring up to 45m deep and 800m wide – could be capable of doing. It would ...

8

"Graveyard Earth" theme park opening soon. According to research, 100 "small" nuclear weapons is enough to initiate a nuclear winter lasting a decade, with temperatures dropping 4C. Ok, that is from 100 nuclear weapons in the 250Kt range. Now substitute that with 195 Tsar Bombas, each 400 times as powerful. That is more than the combined ...

8

Probably very quickly. There's stargazers all over the world, as well as highly sensitive telescopes in space. A 24/7 observation of space is guaranteed. The change might seem minute, but this displacement can create huge discrepancies with the aiming of these telescopes as well as expected data that returns to us. We have apps that can show the position and ...

8

The first thing on the moon that could be visible from earth is already there. A mirror. Will anyone notice, 100 feet away, something else Armstrong left behind? Ringed by footprints, sitting in the moondust, lies a 2-foot wide panel studded with 100 mirrors pointing at Earth: the "lunar laser ranging retroreflector array." Apollo 11 astronauts ...

Only top voted, non community-wiki answers of a minimum length are eligible