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Until about 6,000 years ago, the population of the living people in the world was 4, with none dead. Then Cain murdered Able, prior to the birth of Adam and Eve's third child Seth around 3900BC. ...
The change in pressure below the ocean is approximately $$\frac{dp}{dz}=\frac{1\text{ atm}}{10\text{ m}}$$ where $z$ is measured from the surface of the water downwards. We also have to add in the ...
By definition, the average IQ score is 100. However, the above-mentioned Flynn effect states that average IQs relative to previous years' standards increases. Going by this paper, the increase in ...
I'm very tempted to say that no, that's not possible in practice. At least not without severely stretching the laws of physics. But like Nobody proposed, you could perhaps make it work if you are w...
When will the planet break apart? A solid body will break up if the centrifugal force at a point is equal to the gravitational force. At Earth's equator, the equation becomes $$\frac{GM_{\oplus}}{...
I came up with some basic ideas before posting the question: Space weather Radiation problems can severely damage a spaceship's instruments, making navigation and flight severely dangerous or imp...
So I think a two prong attack. First prong is to remove all the defenses, and an easy way to do that is with EMP's. Launch nukes on SCUDS from container ships 25 miles up over the continents and...
I'd suggest that they may lose at least partial immunity to a decent extent within a decade or two of leaving Earth. According to Smith et al. (2014) (explained for us laypeople here), the number ...
I'm going to take the comment you posted on the question, because it is important. The story should not be driven or build around the technology. But I have the ambition to also not just handwa...
Give it a circumstellar cloud of oxygen. Some planetary nebulae, such as NGC 6826, appear green because of ionized oxygen. Image in the public domain. Yes, this is a true-color image. I see no...
Consider a short-period comet (specifically, Comet Encke). Pros: Very short-period comets can have orbital periods of only a few years, with approaches relatively close to Earth ($\sim0.1\text{ ...
Twitter. (Or Facebook, or other similar vector.) What you need is the "share" or "retweet" concept, a button that a reader uses to put your post in front of his readers, whose readers have a butt...
I can give you a Newtonian analysis of the situation, which may or may not be correct. If you want a Newtonian universe, then great. If you want a general relativistic one, you'll need something mo...
Round objects would be preferred. They'd probably hold cups from the bottom. That would change how their things would be designed more than anything else. They'd like things like stick shifts and l...
A simple extremely high orbit, such as the aptly named Graveyard Orbit - These orbits are really high and designed so that the satellites will be there for a very, very long time. An orbit should b...
You are, in essence, talking to yourself. So you need to make a set of rules that you'll follow. Let's say we have the rabbit in a long cage, and we use Morse Code to communicate with ourselves. We...
So. Black holes are hard to approach. Time gets a little, shall we say, funky as you get closer. And then, of course, there's the tide. They'll tear a ship apart quicker than anything. I won't even...
Lying on their back, on a bed made of some form of comfortable and supportive material, I'd say it's likely that they could survive. The bigger problems come from laying on your back for two days:...
I imagine it'd sound a lot like the sun or a star would, but it wouldn't necessarily be extremely loud. Most sound comes not from the fusion reaction, the fission reactions, burning coal, or whate...
Your own question, a prior answer, and a comment collective already give us several parameters: The human body must be able to produce the sound. The sound must not attract the notice of others. ...
You need to make their anatomies, societies, means of communication, nature of technology, and other seemingly small details so radically different from each other, that even when they see each oth...
How far and how well will sound travel through the sea? First, we need to figure out exactly what the sea is made out of. You've indicated that it's sulfur, but what kind of sulfur? Lopes & Wi...
So . . . modeling the space near two close black holes is actually a really, really tough task. Numerical relativity is extremely challenging; a good example is the intense computations it took to ...
Your creature needs to accomplish two things: 1) escape velocity and 2) survive the harshness of space, all without the benefit of so much as a sharpened stick or flake of rock. This is going to b...
That's no planet! Let's say that the radius is $18R_{\oplus}$, where $R_{\oplus}$ is Earth's radius. The volume will then be $$\frac{4}{3}\pi(18R_{\oplus})^3\bar{\rho}=5832\left(\frac{4}{3}\pi R_{...
