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A very "meta" idea crossed my mind today, and I'd like some feedback. Apologies in advance in case the half-formedness of said idea results in a meandering post. The specific connection I made was that the creation-versus-evolution "debate" could be characterized, at its most basic, as the...

Given a list of values, one calculates the arithmetic mean of those values which are greater than the arithmetic mean of all values. Is there an established name for that quantity?

"Circumference" is superior to "perimeter" in that it denotes or at least connotes the idea of length of a boundary, and not just the boundary as such. Personally, I usually try to pick the option whose etymology best fits the desired meaning, all else being equal - mainly just for the heck of...

The (at least somewhat) established adverbial form is "circumferential". And while "equi-" isn't as specific as one might wish in general (an "equipotential surface" is one which is defined by equal potentials across it, rather than with reference to something else), it should serve well enough...

I doubt it. Coinages are elevated to the status of "name" by being widely used, generally speaking, and to some extent that holds even in a field like this. The reason we have "incircle", and not just the descriptive compound "inscribed circle", is ultimately simply that they're frequently...

Heh. The actual reason has to do with those non-essentials I omitted because they have no bearing upon the problem in its abstract form. What it boils down to is that the point of this optimization is to improve efficiency (a ruler with fewer sections is computationally "cheaper" than one with...

Hello board, in the course of a data processing project I'm working on, this challenge presented itself, and it's a bit beyond my firm grasp. Stripping away the non-essentials, what we have is this: Construct a binary ruler of length L=(2^n)-1 units, subdivided into the least number N of...

Climatology for Worldbuilders I've only had a glance so far, but the material seems to be extremely thorough.

Well, the formula would still be the same, you'd just have to find a new way of calibrating it. The easy way to do that would be to look at typical temperatures for a real planet with the appropriate conditions, just as I looked at Earth. Unfortunately, there isn't any such planet, that I can...

Sorry, I lost track of this thread. 1) To get a rough estimate of how much the day-night temperature gradient changes with day-length, we need an estimate of the equilibrium difference, that is to say, the difference between dayside temperatures and nightside temperatures if Earth were...

Formulae only turn values into other values. As in, v = d/t only gives you a speed v if you know the distance d and the time t already; otherwise, it's nor very useful, except in the conceptual sense. That's behind what we've been saying above: First of all, you need to make up some values to...

Oh, okay. Now, the analogy makes a lot of sense. I guess I fell prey to anglocentric thinking there (and I'm not even a native speaker, either). :tongue: Agreed. They'd be able to do some things much more easily than was the case for our ancestors, by recycling raw materials. No need to...

True for Earth, not necessarily true for planets in general, and likely nothing that simple can be said about seasons on a moon. It could, but you probably don't want it to: If the moon has a surface structure similar to Earth, which is the only obvious way to get anything like Earth-like...

Yes, that's all I meant by "a lot more than halfway there". It took historical hunter-gatherer culture millenia to go from becoming sedentary to utilitizing basic technology (that is to say, the kind that doesn't require supporting technology for the manufacture of the components it uses), like...

I agree, that would make for a lovely premise. A bit like the "pyramids must have been built by ancient visitors from outer space" nonsense, but translated to outer space itself, which makes it a good bit less nonsensical. :smile:

It occurred to me just now that that rules out naming two members of a Power Trio "Harry" and "Hermione" (sharing not just initial letters, but pretty much first syllables)... well, maybe that's the proverbial role-proving exception?

As Ryan tentatively mentioned, a lot hinges on what happens to books, it seems to me. Realistically, I'd expect any disaster which leaves a non-negligible number of people alive to leave a fairly complete corpus of technical literature intact in any given region - undergraduate textbook level...

In all honesty, I don't think it's possible for someone who isn't well-read to become a good writer. Consciously or subconsciously, your audience will always be judging your writing against a common standard established by everything else they have read. If you don't know this standard...

Yes, that is true. And there are some prides which have specialized in targeting prey conventionally thought of as being outside the size range manageable by lions, such as adult hippos and even subadult and elderly elephants. In those cases, the dominant males do uncharacteristically...

Yes, that's where this idea came from, actually. :smile: Lyons are the direct descendants of lynxes. The latter are solitary and have the characteristic ruff of hair and moderately enlarged canines, only slightly larger than those of Earth's clouded leopards, which is the most "sabre-toothed"...

Lyons (from lynx + lion), in my world, are mid-sized (20-40 kg) feliform predators. They live and hunt in groups called prydes (obviously), and are large-prey specialists. The principal prey species are ellefants, which are miniature mammoths (about an ell tall, thus the name), and deer, which...

^ Exactly. And the post mfb's was in reply to specified that this is a "massive black hole", so we don't even have to rely on its conforming to the known/predicted mass range. No capture is possible between the two stellar-mass objects without the assistance of at least one other in that range.

The thing that causes a supernova is a runaway nuclear reaction in the stellar core. Think atomic bomb with a mass of, well, the Sun. That reaction produces large amounts of both radiation and subatomic particles. The first and foremost effect of the reaction is to "blow up" the stellar...

I suspect that won't do it. For example: Direct sunlight has an energy content of about one kilowatt per square metre. A human pupil is something like 3 mm across, so its area is 10^-5 square metres, which gives us an energy flux of 10^-2 Watt. A visible photon has an energy of some 10^-19...

It stands to reason that he'd be effectively blind, I'd say. Without even having to think about it in terms of redshift, just consider that the amount of light that hits our retina in one second would hit his retina spread out over a billion seconds. In other words, he would see the world at a...

Perhaps, but not by much, would be my tentative answer, based on the wikipedia article. Mercury's rotation is tied to its orbit by tidal resonance effects, specifically in such a way that the Sun will always be more or less stationary in the sky when the planet is close to perihelion. At...

I certainly agree with Ryan on one thing: If anyone thing goes seriously wrong in a closed ecosystem, once the outside world has become uninhabitable, the results won't be like those of the man-made or natural disaster we are used to. The result will quite simply be that everybody dies. Thus...

Nah, it doesn't really work for me, no matter how restricted. If one draws power from only one thing, then one should have power over only that one thing. Anything else feels a little jarring. Needless to say, that's just my opinion. Your work, your rules, obviously. Maybe have a little...

Yeah, as I said, anything that utilizes Air or Water or Fire directly would feel off to me, given his Earth-powers. A pressure wave would be using Air directly, obviously. He could be able to throw rocks (which are part of the Earth) with high speed and precision, which would take care of...

Stands to reason that if he can absórb power from the Earth, then he can also transmit power through the Earth, it seems to me. Something like stomping his foot over here to create a localized quake over there should definitely be within his abilities, therefore. But throwing a punch over...

I actually agree entirely. That is how these things work in cartoons and comics, I imagine because of some vague analogy to a "battery" with which one has to make "contact". As I said, this may not be scientifically plausible, but it doesn't strike me as far-fetched by the standards of your...

Nono, non-rotating frames are privileged over rotating frames, even in relativity. The problem would be of a more practical nature - how do you extract rotational energy from something without having a quasi-Archimedean "place to stand" which doesn't rotate along with it? I suppose the Moon or...

How different was the other estimate? I'd like to know for my own worldbuilding.

^ I tried a rough estimate here a while ago.

The total rotational energy of Earth is on the order of 10^30 Joules, which corresponds to trillions of stupendously huge nuclear weapons. Converting all of it into heat would be easily sufficient to melt the Earth's crust, thus definitively eradicating all life. So, we're talking about...

^ Yeah, that's what the first bullet point in my OP was asking as well. Unless someone tells me otherwise, I'm just going to assume that local variations in tide amplitude can be ignored. To increase it by an appreciable amount somewhere other than in a narrow fjord or some such, you'd have to...

:smile: Thanks for that! I'm going to wait and see if others can shed some light on the various questions you raised before replying in detail, except for the two points below: I've more or less adopted mfb's suggestion from post #14 regarding the white dwarf, i.e. that it only recently...

Pragmatically, that makes sense, but it makes the moral high-ground of any subsequent "the survival of the species requires it" justifications rather shaky, don't you think? That would be my perspective in such a situation, anyway.

Why is an undocumented worker less likely to contribute to the survival of the species than a documented worker? What's the timeframe covered by your plot? I was assuming that it continues well into the future of the cataclysm, but you keep only talking about the initial stages, so maybe...

I partly agree. If what people see is that an authoritarian government is murdering people they love and like, the impact on morale would be disastrous. However, if the situation is one in which people for the most part believe that such measures are necessary for their own survival, humans can...

What about later on? There could be measures like enforced abortion if a fetus is showing any signs of abnormal development, and no medical care for those too old to productively contribute any longer, and so on. If the agenda is survival at any cost, those decisions should be made solely on the...

Oh, true. I guess my mentally equating them with lifeboats wasn't really appropriate after all, because of that aspect. Thanks for pointing that out! :smile:

I'm not sure excluding the old makes any sense in this case. It does if the impending disaster is only expected to last a time much shorter than a human lifetime, because then you want as many persons (women, really) of childbearing age as possible when things go back to normal, allowing you...

^ The standard plot device for adressing the humans-are-selfish issue is to allocate at least a fraction of the available places in the "lifeboat" by last-minute lottery. As long as the lifeboat in question offers significantly better survival chances than anything that could be accomplished...

One can only become The Champion if one is undefeated. Thus, if nobody whatsoever makes it to the second round, there is no champion. Baaad omen, presumably. The weapons used are such that fights are typically to incapacitation rather than death, and killing one's opponent is frowned upon -...

More detailed explanation, please.

Say there are N gladiators, and I want to find the champion among them. The method by which this is done is a series of elimination rounds, which are similar to but not quite like the methods used in many modern sports events: Each gladiator is given a number from 1 to N. Each gladiator then...

The key concept here is "being in free-fall". You do not feel any gravitational forces with respect to which you are simply falling. That includes the Sun and the Moon, and, for someone in orbit, the Earth as well. Analogously, it includes the Black Hole. The only reason we do feel the...

For an Earth-like atmosphere (one which can indefinitely retain relatively light molecules like methane and water), a rule-of-thumb bound is given by (R/M)*T < 2.5 REarth/MEarth*TEarth where R, M, and T are the planet's (or moon's) radius, mass, and temperature (more). If the planet is to be...

^ This is indubitably sound advice, but also exactly what I meant by "the usual trite genre-independent writing advice". There is nothing wrong with that as such, but the problem is that there's so much of it that the less obvious and thus more valuable insights exemplified by the two quotes...