CaptainPanic

To create power with steam, you do not need temperatures associated with molten rock. A much lower temperature (i.e. a few hundred degrees Celsius) is also still acceptable. Volcanic power is used at quite a large scale. Iceland has a LOT of these power stations. However, it is much better to drill a hole a few kilometer away from the volcano than to use the slope of the active volcano itself. The temperature is still sufficient, but the rocks are more stable.

It can definitely be interesting to build two separate infrastructures, although I believe that the separation that people want to make is between dirty water (i.e. waste water from households) and rainwater. The rainwater may be used for irrigation, but also for flushing toilets. While forest fires are a real problem, you shouldn't underestimate the amount of water used for flushing toilets on a global scale.

Wikipedia has a list of unmanned urban metro / subway systems. Those are local trains, right? https://en.wikipedia.org/wiki/List_of_automated_urban_metro_subway_systems

Do not use your elevator shaft as a drainage pipe. I do not think that we have to discuss that at length. However, making sure that not all the water hits the sewers at once is a major change in thinking. Not too long ago, cities were built with the philosophy of removing rainwater as soon as possible. Drainage canals were made as straight as possible to give the water the quickest way out. And that works really well as long as these canals do not exceed their capacity. The new philosophy is to create intermediate storage for the water. If all rainwater hits the sewers during extreme rain, these are almost certain to flood. So, you have to store it first, and release it into the sewers in the hours/days after the rain. In the Netherlands, a lot of progress is made. Take the "water square" for example: http://www.urbanisten.nl/wp/?portfolio=waterplein-benthemplein A square which is used for recreation (relaxing and skating) most of the time, but which can store thousands of m3 of water if needed. Dutch cities are all replacing asphalted and paved areas for grass, which absorbs more water. Cities are building creeks and other drainage systems, which are deliberately not straight, and not only add to the capacity to remove water, but also stores water while it rains.

You should give us some more boundary conditions of your assignment. A good economic analysis of the production of a chemical is quite difficult! It involves a comparison of multiple reaction routes, and includes an estimate of the costs of the factory for all routes (investment and operating costs). I kinda doubt that your assignment is that complex. Have you found any papers yet that describe the reaction routes? Maybe you can post the links you found so far here, then we can point out what is important in those. But please do not expect us to do a literature search for you. That is your homework, not ours!!

Guys, my question is answered, with some extra's as a bonus! Thanks! Of course, if you're interested to continue a discussion, feel free!

The first that comes to mind is the regular smoke machines that are used in clubs and parties. Those are not as hot, are not very dangerous and can be turned on and off at will. Seems ideal for you? You can also use a search engine to look for mist makers. These are tabletop gadgets that make a little mist. Some can be so small that they can be integrated in a small scale decor for a tabletop roleplaying game. Finally, some people use frozen CO2 (dry ice) to create "smoke". It has the benefit to stay close to the ground, giving a spooky feel to it. Essentially, you locally make air very cold so that the water in the air condenses and form a very small fog. Cold air is denser, so that's why it sticks to the ground. Not sure at what scale you need the smoke, and whether people need to stand in it. CO2 comes with some safety issues (it can be toxic at higher concentrations!!) so be careful with it if you make it big.

This is exactly why I posted here. Thanks! In our discussion, we were arguing whether the Kerbal Space Program solar system would be possible at all. We'll just ignore whether interstellar gas clouds want to form such solar systems at all, but just assume they did and now we want to check whether this solar system makes any sense at all. So stars could possibly be much smaller, but burn as bright as our Sun. In the Kerbal Space Program solar system, the central star is also scaled down, probably with a factor 10 (I think in radius!), but it shines like our own Sun. Under the assumption that this is governed by a smaller gravitational constant, I read that this would be actually expected. Also, assuming the universe is as old, heavier elements should (start to) become more common than in our universe. The game predicts very little about this, but it is interesting to know! Would elements heavier than iron also be expected to be more common? Anyway, thanks for helping out in our pub discussion! Much appreciated!

Actually, you'd be surprised how politically neutral Kerbal Space Program is. No mention of any POTUS, or even of countries.

Hey all, It’s been too long since I showed my digital face around here! But I am stuck on a question and this seems the #1 place to get some quality feedback, so I dug up the password and logged in. All is well on my end, hope you’re all doing great too. Tl;dr Other than gravity itself, orbits of celestial bodies and the attraction of objects (i.e. people) to the celestial bodies, what else would be affected if you change the gravitational constant from 6.67*10E-11 to something a lot larger (say 6.67*10E-9)? Longer version In a fantasy universe, such as exists in the Kerbal Space Program universe, planets tend to be 10x smaller than in our real-life universe and solar system. The reason that the programmers did this is to make the gaming experience nicer: you can orbit a planet in just 30-40 min, rather than hours. In a pub discussion, we were discussing how the physics of this would work. The gravitational acceleration at the surface seems unaffected, and is still something around 9.81 m/s2. Since the planet is so tiny, you’d expect that the gravitational acceleration at the surface is much lower. But it isn’t. So either the planet is incredibly dense (maybe some fantasy-elements in the core?) or the actual gravitational constant (G = 6.67*10E-11 m3 kg-1 s-2) is different in this universe. Of course, in a fantasy universe, you can write whatever you want. Kerbal Space Program is just a game, and the programmers have total freedom. But if you’re expanding the game to include more models of physics phenomena, would you run into problems because the gravitational constant is different? The orbits of planets and my space ships are stable, so those would work with a different gravitational constant. But would there be any other phenomena in which the gravitational constant plays a role? p.s. Kerbals are one of the reasons for my inactivity here. Been rather occupied launching rockets. That, and life just got busy in general.

In my family, it was figured out the hard way: by digging into the old sources, such as tax records, marriage documents and registration of houses - those date back sometimes hundreds of years (at least in the Netherlands). Typically, it is rather easy to trace it back as far as the time of Napoleon, since Napoleon (or rather his officials, not him personally) kept pretty good records. Beyond that, you gotta be creative and get lucky.

I suspect that despite the article's title calling this "large scale", the Chinese consider this 200 MW plant a 'pilot/demo' plant. If proven to be economically and technically feasible, their idea of "large scale" may just be a little larger than we realize. I would suggest you look at this regarding the price (which is closely related to the usefulness) of the land you're using. If you place this in the Gobi desert, which is largely uninhabited, and non-arable, nobody really cares if you use lots of land there because it has no (or very few) other uses. The Drax powerplant is located smack in the middle of a densely populated and cultivated land. It's actually using up land that could easily be used for many other purposes. The main issue of the location is that you must transport that electricity to somewhere else, which comes with its own investment and energy losses. I wonder how robust and efficient the Chinese electricity network is. It's mostly quite new, but it is a topic that I don't see a lot of news about.

This thread is ancient (it started in 2008), but it appears this is the first actual Air trecks built... even though their name is Razerblades, rather than airtrecks. Congrats to the creator (named Charles). Check out that website, it is worth it.

Destroy humanity (and leave the rest of the planet alone): probably easiest with a virus? Nuclear war might be another option. Destroy all life on our planet (but leave the rocks alone): you'll need more than all the warheads on our planet. But building many many many more warheads might achieve it. An asteroid of 10 times the diameter of the one that finished the dinosaurs too (but I didn't do the math, so if you wanna make sure, get an even larger one). Break our planet apart (but allow it to settle back into a new planet): smash something the size of our moon into it. Break our planet apart permanently: either slow it down enough to make it fall into the sun (you can calculate the kinetic energy you need to overcome), or smash something incredibly large and fast into it. Janus gave you an answer a few posts above, but I am not able to check it. But since the question was not clear: I advise all of the above.

Harold Squared, In this thread, you made a lot of claims, and explained a number of ideas. And people asked you a bunch of times if you can show any evidence about how this is supposed to work. When people ask that, it means you show some publications, or some studies, or some research papers, or even some news articles that back up your claims. It does NOT mean that you must explain your idea a little better, as you have been doing until now. The joke about the unicorns was quite serious. Of course, people here know unicorns don't exist. But until you start showing on which underlying assumptions you have based your claims, your story is just as good as the one about unicorns.

Funny that you choose a Chinese investment: The Chinese are by far the largest investors in sustainable energy. And that always makes me wonder: If sustainable energy was such a bad idea, then you wouldn't expect that they would invest so much, as the Chinese government obviously doesn't have to please the tree-huggers in the next elections. Source for the claim that the Chinese are the biggest investors: Bloomberg report (see page 10 for most comprehensive chart of 2014 investments) Note: .pdf warning

It's all in the dosage. (Same goes for oxygen, 20-21% is good, but both too high or too low can be dangerous). We need sugar, and sugar is an essential part in our metabolism. Sugar (glucose) is vital to provide energy to our cells. But too much of it, and we risk diabetes, cardiovascular diseases, etc. Yes, I know that processed foods contain unnecessary amounts of sugar - it is added for taste (test groups will simply appreciate the food with sugar more than the food without), and sometimes as a preservative. But we're not discussing either of those two points. We're discussing whether it is 8 times more addictive than cocaine. And I am not convinced yet that somethibg that is essential to our existance, and which we need on a continuous basis just to survive can be called addictive. Sugars, just like some (all?) drugs trigger the reward system in our brains, and eating/drinking it makes us happy. I am simplifying things here, because I cannot be bothered to up the terminology. The main problem I have with this thread is that as we evolved all these reward systems were purposely set up to be triggered by sugars. It's the other drugs that sort of cheat our reward systems, and are addictive as a result. But we're supposed to feel happy eating sugars. Only since we started making large amounts of cheap processed food have we run into problems, because suddenly foods that shouldn't contain sugars start triggering this reward system... but that does not mean we can call sugars addictive. Googling around for addiction and sugars, I do find some other sources, most of them connect the fact that our reward systems are triggered with sugar use... but I haven't found any credible source that really calls it addictive. [edit] I noticed too late that dimreepr and Fuzzwood also posted. It took me a while (>1 hr) to write this post in between other tasks... I'm afraid I ignored their contributions in this reply.

Meh. I argee with MonDie: Oxygen (O2) is probably the most addictive compound in the universe. We can't go a second without it. Yet nobody has banned it.

According to the news, the guy in the blue shirt was actually sitting in a small pit, doing some maintenance work on underground cables (internet or phone cables). And in a sad turn of events, today the mayor of the town (called "Alphen aan den Rijn") complained in the Dutch media (in Dutch, obviously) about tourists who want to see the destruction with their own eyes, who climb into people's (private) gardens, and climb onto cars to get a good photo of the accident. About half the twitter updates (in Dutch) from the municipality are requests to not get in the way of the emergency services and investigation teams... That's what you get in 2015 if your accident goes viral on the internet. People will travel to the spot, to take a selfie, so that they can get many likes.

Dutch media (it happened in the Netherlands) report that there were no injuries or fatalities, except for a dog who didn't make it. Some people got extremely lucky getting away from that. Have a look at this security camera footage of one of the streets near the accident. It's a small miracle that nobody got hurt when you see how many were in or near the place where the crane came down.

What I understood is that there were a lot of small investors, who put their life savings into the stock market, or even borrowed money to invest on the stock market. First, all this extra money created a bubble. Once the market went down though, these small investors all got scared (people react differently when they are investing a company's money, or when it is their own retirement). They all pulled their money out, and this caused a more excessive response than you'd normally expect. Together with the fact that it was indeed a bubble meant that the stock market went down a lot, really fast.

It would be a pretty low-maintenance defensive line. imatfaal, thanks for the link. It is the best explanation (and the only one with a link) so far.

Just a small side note: You can totally use Linux without knowing anything about the command line, just like you can use windows without understanding the DOS command line. But I realize that this is slightly off topic.

A quick reply to the original question (post 1). I run Linux on a desktop at home. The desktop has 2 harddrives, which makes my life really easy. One has the operating system(s), and the other has all my data. If I want to (re)install Linux, or try to install a 2nd system next to it, I just physically disconnect the data drive, then reboot to check that I disconnected the correct one, and then proceed in install a new operating system.

As I was taking a little summer holiday in Russia by browsing on google maps, I found some weird features in the Russian landscape that I cannot explain. There are triple or quadruple rows of trees (or other types of green), which extend for hundreds of kilometers through the landscape. Here's an example of a triple line. Here's an example of a quadruple line. Here's one that crosses through a town, to give a sense of scale. Finally, here's one just outside of Volgograd (formerly Stalingrad), which seems to give a possible hint about what this is... These lines seem to have little to do with the borders of the oblasts or other governmental regions. The line just outside Volgograd suggests to me that this is a line that indicates the furthest advance that the German forces made in WWII (even though it is outside the city, and I thought that the battle took place inside the city)? The scale of these lines (hundreds of meters wide, stretching hundreds of kilometers) is quite mindboggling. I've searched the internet for quite a while now, but I haven't been able to find a single reference to what these are. Guesses are welcome, but links and sources are what I am really looking for!