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Q&A Would a large, close-by, molten moon be able to support photosynthesis at night?

Let's assume that the Moon is roughly a black body. Therefore, its luminosity can be approximated by the Stefan-Boltzmann law: $$L=4\pi\sigma R^2T^4$$ As you've said, $T=1100^\circ\text{ C}=1373\te...

posted 7y ago by HDE 226868‭  ·  last activity 7y ago by HDE 226868‭

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Q&A Would it be possible to punch someone into space?

On Earth, escape velocity is about 11 km/s, or 11,000 m/s. Assuming the opponent weighs around 70 kg (maybe more), that's a kinetic energy of at least $$\text{KE}=\frac{1}{2}mv^2=\frac{1}{2}\cdot70...

posted 7y ago by HDE 226868‭  ·  last activity 7y ago by HDE 226868‭

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Q&A Which factors are more dominant when it comes down to atmospheric escape?

I wrote an answer on Physics Stack Exchange that discussed this a bit. I'll present a shorter and more focused version here. There are two main processes by which a planet can lose atmosphere: Jea...

posted 7y ago by HDE 226868‭  ·  last activity 7y ago by HDE 226868‭

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Q&A Could planets be at relative rest with respect to each other (in a game universe)?

You need to take advantage of Lagrangian Points. Whenever one massive body orbits another, there are five points surrounding them where other massive bodies will be in equilibrium, in terms of gra...

posted 7y ago by cobaltduck‭  ·  last activity 7y ago by cobaltduck‭

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Q&A Building a city on top of, alongside and inside a coastal cliff

(NOTE: I started writing this answer before @amflare posted theirs, and before @AlexP posted his comment.) The existing answers do a good job of demonstrating that you can build a city on the side...

posted 7y ago by F1Krazy‭

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Q&A What could cause the Earth to be so endangered that mankind needs to relocate to another system?

When the sun started to behave strangely, astronomers were confused: The accepted solar model didn't at all predict this behaviour. Indeed, based on the new data it could quickly be shown that thei...

posted 7y ago by celtschk‭

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Q&A What could be a valid reason for an entire section of a continent to remain unexplored and undiscovered, by the rest of the world in medieval times?

People do discover it. They just never report back. It's one thing to sail all the way to a new continent. It's quite another to land there, chart the territory, and then sail back home again to t...

posted 7y ago by F1Krazy‭

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Q&A Would a 2 thumbed hand increase grip significantly?

Reptilian with multiple opposing digits? Sounds like chameleons: photo source Yes, our little Madagascan color-changing friends already have the arrangement you are looking for. Why? Because...

posted 7y ago by cobaltduck‭

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Q&A How long before we're stuck on Earth due to Space Debris? (Kessler syndrome)

A couple hundred years. In 2013, the Inter-Agency Space Debris Coordination Committee (IASDCC) published a report detailing comparisons of several independent models (one each from ASI, ESA, ISRO,...

posted 7y ago by HDE 226868‭  ·  last activity 7y ago by HDE 226868‭

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Q&A In an elliptical orbit, where should a rocket fire its engines for maximum efficiency?

Fire the engines closer to the Sun for maximum efficiency. This is due to the Oberth effect. Assume the spacecraft undergoes a burn when it is farther away from the Sun. The expelled propellant wi...

posted 7y ago by HDE 226868‭  ·  last activity 7y ago by HDE 226868‭

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Q&A Gravitational lenses for focusing giant lasers

Probably not. After some more consideration, I'm less confident that the proposal could work. There are two reasons: No guarantee of focusing at any one point, and an inability to control the para...

posted 7y ago by HDE 226868‭  ·  last activity 7y ago by HDE 226868‭

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Q&A Man-powered spacecraft for sport

Solar Sails. Without any sort of compressed gas, chemical reactions, or flywheels, the only way you're going to get a spacecraft to move is via something outside. A human simply cannot provide any...

posted 7y ago by Andon‭

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Q&A What kind of stellar core or degenerate material would be needed to create a survivable explosion?

Interesting question. I'm reasonably certain that the answer boils down to a property of matter called the equation of state. An equation of state is a relation between several thermodynamic varia...

posted 7y ago by HDE 226868‭  ·  last activity 6y ago by HDE 226868‭

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Q&A What would happen if an object on Earth has an equal or greater gravitational force than the Earth?

Neutron star material, if it could be contained by means other than its own gravity; would require a cube about 390 meters on a side to equal the mass of the Earth, if it could somehow be 'placed' ...

posted 7y ago by Amadeus‭

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Q&A Genetic diversity in an interstellar society

I think isolation is still there; occasional visitors from off world notwithstanding. Our features are environmentally driven: The caucasian nose, skin color, eye color and hair are all adaptations...

posted 7y ago by Amadeus‭

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Q&A Advanced alien insect long range communication

I think it is fair to assume these insects are haptic; meaning they have some sense of touch in their environment. Then the solution can be a code, like humans have, developed along the lines of mo...

posted 7y ago by Amadeus‭

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Q&A Is this kind of lifeforms and ecosystem on Enceladus plausible?

I don't think this is plausible. How did they become smarter than humans? The most plausible route to Intelligence is that it evolves in an environment where it is useful, that is where it exists ...

posted 7y ago by Amadeus‭

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Q&A Could burning debris keep burning in space?

First off, something that might seem like an inconsequential detail or perhaps even nitpicking, but really isn't in this case: You don't need oxygen for something to burn. What you need is an oxidi...

posted 7y ago by Canina‭  ·  last activity 7y ago by Canina‭

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Q&A Could a self-aware bacterial supercomputer start its own ecosystem?

This actually relates to the OP's question; give me a minute. Self-awareness does not require an internal dialogue or a language in which to speak. Self-awareness is having a mental model (simulat...

posted 7y ago by Amadeus‭

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Q&A How to create a seawall with medieval technology?

Yes, obviously, if stone materials are available. The pyramids were built, right? Stonehenge was built. The Roman Coliseum was built, and we know how. Infinite money and workers means stone walls ...

posted 7y ago by Amadeus‭

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Q&A Are these conditions for a planet realistic?

All your settings are completely plausible. I upvoted the @ventsyv answer; but I need to correct one thing: Planets can rotate at any speed; in any direction; thanks to collisions during their fo...

posted 7y ago by Amadeus‭  ·  last activity 7y ago by Amadeus‭

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Q&A How physically small can human intelligence get?

From Here: "The average human brain has about 100 billion neurons (or nerve cells) and many more neuroglia (or glial cells) which serve to support and protect the neurons (although see the end of t...

posted 7y ago by Amadeus‭

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Q&A Can I detect one ship arriving in an otherwise abandoned solar system?

I'd say yes; in the scenario the listening ship can set up sensors that are literally miles long; like the gravity wave sensors that have recently made headlines. Think, as an analogy, about motio...

posted 7y ago by Amadeus‭

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Q&A Would humanity survive an empty Earth suddenly populated with young children?

Children the age of 3 can be trained to recognize dangerous vs acceptable vegetable foods. At age 3 they can be in kindergarten and learning. They can also learn to acquire berries, honey, and to r...

posted 7y ago by Amadeus‭  ·  last activity 6y ago by Amadeus‭

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Q&A Tentacles as "hands"

A) Consider the human tongue; a long boneless appendage, muscular, that (in some people) can manipulate finely enough to tie a knot in string (perhaps holding one end in the teeth, I don't know). ...

posted 7y ago by Amadeus‭

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