CaptainPanic

No, of course you should search for an answer! I am only saying why you may not find it [edit] Actually, it's Feynman who is saying it, not me...

This. +1 Most people only see a bunch of pipes, and don't know the complex system behind it. Hundreds, or even thousands of streams with different chemicals at different pressures and temperatures. All controlled by valves, compressors, pumps, heaters and coolers, which in turn must be integrated and controlled by actuators which are connected to computers. All integrated into a complex system of logistics that brings in raw materials and removes products from the site.

What is self-sustaining? Even if a relatively small group would be able to stay alive, how would they have a functioning economy? Life on Antarctica needs some fancy gear and materials which only the larger economies are able to produce. There would have to be some trade, and in order to be able to buy something, you need to sell something. But other than tourism, I can't think what anyone would want to have from Antarctica. Ice?

Sorry if this does not address the major issue of global welfare and a better society, but I just want to say this: The concept of bread and games, to keep the people happy is not just a way to keep the masses under control. Some entertainment is important for a society. The problem with the really high salary of football players is that it ruins the competition, not that it is such a large cost to society (it's not). Personally, I think that we should just reduce our overhead costs: reduce the number of jobs in useless sectors. And I think that the financial sector could be halved without any problem.

As you can see in the video (0:18 min) "We have asked for it back, we'll see how the Iranians respond" does not sound like a declaration of war against North-Korea, does it? So, no there won't be any new wars. [edit], oh, I see where you got your misinformation: FOX news is not actually a source for news.

Eehm... the stealth drone was downed over Iran. It was not shot down, but instead the controls were sort of hacked. And it was the US who were flying a drone in the airspace of another sovereign country, and it was therefore the US who broke international law. And no, the US cannot afford another war. They are already practically bankrupt. LOL, how could you get so many mistakes into such a short post?

Look up the Nusselt number. Sorry to give a short answer... but the long answer is really too long. I hope that the wikipedia link helps.

Gotta love climate discussions. JohnB, you start your post with a nice fallacy (above), and since this is climate-change-discussion, I will accept that as a standard method of discussion. No, I am not afraid, and fear has nothing to do with it. But I will dress different in winter than in summer. In summer, when it is warm, a t-shirt and shorts can be sufficient, while in winter I wear multiple layers to prevent hypothermia, and I usually make sure that the outer layers of my clothing are water proof when it is likely to rain. Also, when it is going to rain and there is not much wind, an umbrella will keep me dry. Rain in the Netherlands is inevitable, but I generally stay dry. And if I am myself the reason I am cold, then I will address this problem, either by turning on the heating when inside, or by improving my cloting when outside. The winter is inevitable, but I have many options to survive it. I can make sure that the air around me does not cool me down, or I can make sure that some insulation (clothing) keeps the heat in. Regarding the climate, you may oppose the idea of reducing our footprint. I think it's a bit selfish, but that's only normal for humans. But do you also oppose any ways to deal with any climate change? Will you walk in a metaphorical blizzard in shorts and sandals? Or will you at least support building dikes in areas that may flood or improved irrigation to reduce water losses in areas where drought may be a problem? Personally, I think it would be wise to allocate an amount of money similar to the military expenses to prepare for climate change. Luckily, in the Netherlands we do that already. We sadly spend very little on sustainable energy, but luckily we at least acknowledge the possible changes, and we are continuously improving our dikes. War might be avoided, but high water will surely come to us, from the rivers or from the sea. And we have already spent many billions to prepare. And guess what, that even turned out to be good for business. The Dutch now sell their expertise.

The poll is flawed. When asking about the frequency of reading ebooks, "Never" should be included in the list. Call me old fashioned, but I don't see the point. Also, are you sure that for a student the major costs are the readers? Because study books are often printed in relatively small numbers, they are expensive. E-readers won't change that... although a search-function (ctrl-f) would be very convenient in a study book. And can you study with just 1 book open? I remember that, as an engineering student, I often had multiple books open at the same time. I also do not know if I would be happy to leave some large companies in charge of the digital rights of the books that contain all I need to know for my career. It is said that the rights of the books are still with the companies, and that what you buy is more like a license to borrow, rather than complete ownership. I don't like that idea - not for regular books that I enjoy, but especially not for stuff that I am being paid for. As for normal books (novels, etc.), at the price of an ebook-reader, I can purchase 10-20 books (they start at 3.50 euro in the 2nd hand book shops). Also, they require no batteries, can legally be shared with friends at zero cost and require no updates, and have no drm. I know that I will be one of the last people to change to e-readers. but maybe this thread will change my idea of them.

When I did such experiments (I really don't understand why Zolar can't buy 2 magnets for like 1 euro in total), I had 2 short bar-magnets. I put tape around them until they could be jammed into a straw (the ones you get for free at McD's). You want the "string" you hang the magnet from to be straight anyway, so something more firm (but still lightweight compared to the magnet) is good enough. Then the flexible joit at the top was done with a regular string. If you, like swantont seems to suggest, wish to calculate the exact force, you should indeed also include some scales to account for the attraction of the magnet which is on the bottom. Kitchen scales will quadruple the costs of the experiment to a staggering 10 euro. What I enjoyed the most is if you suspend a magnet, and you place a bunch of magnets on the ground... the hanging magnet will be a pendulum, but will behave quite chaotic. And although is a nice-looking setup, this can be built at home with very basic stuff.

Sadly, such large amounts of money are exactly what is needed. But of course, most of you will agree that it is impossible to relocate all the defense budgets to sustainable energy. I just cannot imagine that I would have to explain that to some alien, who isn't brainwashed by our modern world: Me: "Yes, we know that it is quite likely that we have a massive problem, and the entire climate might change." Alien: "Ok, so you allocate a lot of resources to fix that, don't you?" Me: "No, we prefer to spend that on tools to destroy each other." Alien: "Oh, that's sad... so, war is inevitable, isn't it?" Me: "Well, where I live, the climate change seems a lot more likely to happen than war, actually." Alien: "Eeh..."

It's not likely that your brain actually swells, but a severe lack of sleep is going to affect a lot of things in your body... iNow already posted a good link in post #2. Read it. You cannot go on like this forever, so you might as well try to solve it right now. Get some help, change the shifts, or change the opening hours.

URAIN, although it is not really on topic, I think you should watch . A famous scientist (Feynman) explains why things cannot always be explained.

The real issue The main bottleneck is simply the fact that we're 7 billion people now, and still growing! And there is nobody who is doing anything about that. Technology cannot solve anything if we keep breeding like rabbits. People can definitely create more people quicker than they can create the necessary infrastructure/energy to deal with those people!! But let's focus on the topic of this thread: energy. Back on topic The technology to generate all our energy form the sun's radiation is efficient enough. Heat We can provide heat at about 70% efficiency on sunlight. Solar boilers are that efficient. Electricity at about 20% efficiency. And if you realize that wind is a waste product from solar energy, and wind turbines use waste heat from the sun, this is even higher. Electricity Generating electricity, also for transportation (using batteries) is a matter of investment - of money. We only need to allocate enough money, and thereby people and resources to build it. The technology exists. People may complain that battery-life is not enough, and that their cars would run only 100 miles instead of 400, then we'll eventually solve that. And people say that it's more expensive. Again true. That doesn't mean that it's impossible. If you want to buy something expensive, you cannot buy something else. So, perhaps in the future, cars will be more expensive. Food/water The real issues are food and water: plants are only (max.) 1% efficient, and when you wish to convert plants into meat, eggs or cheese for example, this drops to 0.1% efficiency on sunlight or lower. And then suddenly the earth is a very small planet when there are 7 billion people. But a hungry person is an inventive person, and it seems we can still expand. It's nature who is suffering the most. And the availability of water is another issue... it's not so easily expressed in terms of the sun's power (although it is related). Energy enables us to generate drinking water. But that is incredibly expensive (in terms of money and energy) compared to ordinary rain. But there will be a water shortage sooner or later... because the population will keep growing, and growing, and growing.

I disagree with a couple of things here: 1. We have 7,000,000,000 people (one more zero). 2. The sun shines with so much power, that its power on the earth is still several orders of magnitude higher than our (fossil) energy consumption. 3. We can definitely generate enough power with sustainable energy. It's an economic problem (we don't want to invest that much in it) rather than a fundamental problem. So, if we switch on time, there is no problem. So, I dunno... since this is an economic problem, and we are in an economic recession, I guess that for the time being, we're lucky if we invest a little in some small enterprises. Let's hope that the industry is ready to go once we're out of a recession (if ever). And let's hope that the Chinese invest in sustainable energy.

Temperature can reduce the density of a gas without changing the pressure. But to go back to the OP, yes, the air in higher layers of air indeed pushes down (it is also attracted by gravity). That weight in turn compresses the air below, which is thus denser. Gravity is not much different at the earth's surface or 10 km up where the air is a lot thinner. So, you cannot say that the air is so much thinner up in the atmosphere because the gravity is less. It's not. (Well, actually it is, but only a tiny tiny fraction). To be honest, I don't see why Dalton's law would contradict with how our atmosphere works. In other words: I don't understand what you don't understand [edit] Oh, I see that my answer is a little late. Nearly 6 weeks late. I hope it's still relevant.

The question "what is time" is something which will ultimately descend to very existential questions and debates. People start doubting about everything, and before long someone will ask you what is your "consciousness"... and frankly, nobody really knows. By the way, we are not "science". You cannot "ask a question to science". Science never has any answers. Only observations and theories. But the funny thing is, science always doubts about itself.

Let's take this one step at a time. a bit pedantic, I admit, but the NaCl and the water together form the aqueous solution. Because the sodium which explodes is metallic sodium (not Na+1, but Na (zero)). Once the Na has lost an electron (and becomes Na+1 as a result) it cannot "explode" anymore in contact with water. The two half-reactions are: [ce]Na -> Na+ + e-[/ce] [ce]2 H2O + 2e- -> H2 + 2 OH-[/ce] Put those two together, and you get: [ce]2 Na + 2 H2O -> H2 + 2 NaOH[/ce] And about the taste? Well, Na (metallic sodium) simply tastes very different than the ion. Just like rust tastes different than iron, and hydrogen and oxygen gas taste different than water.

In another thread, we discuss the condensation of water from a humidifier. I think my question is too much off topic, so I created a new thread. The main question is: What's the point of a humidifier? I never understood the problem with humidity actually. After all, people live from the deserts to the rain forests, and it's not like there are certain areas in the world where everybody is sick. It's perfectly normal to live in a country with 75-100% humidity most of the time (e.g. the Netherlands), or in countries where it is quite dry. Here's a map of the world showing relative humidity. Because I live in the Netherlands, which is naturally wet, I have never seen a humidifier like this (wiki) in my life. I don't think they are very popular in Europe actually, not even in the Mediterranean countries where it can be quite dry in summer. In houses with radiators, I have seen a simple humidifier, which is just a water container hanging against the radiator, but I don't understand why people use those either. It seems like a waste of energy to evaporate water in a naturally wet country. But the electric appliances that I see in Google seem able to put a lot more moisture into the air. Why? Can anyone explain what happens if you live in a house without humidifier? What's the point of having one?

The big question, as has in different words been said a couple of times is: what makes you think that the graphene survives against a rock or a steel plate? Sure, it's thin, but it's just atoms against atoms. Why wouldn't the graphene atoms break off instead of splitting the rock or steel plate?

I do not think there are "typical pressures". It is very dependent on the size. Small boilers might not hold a very high pressure and if it is a hobby project, to build at home you definitely want to be on the safe side. For small table-top steam engines, you might just as well buy a complete kit at a local shop. That will come with a manual, and will tell you all about the safety. Large scale industrial boilers can achieve hundreds of bars. Here's a link to a supercritical steam plant, operating at 280 bar, 600°C.

Spammers, take notice, this is how you hijack a thread, and talk about the iPad for iCrap (*points to posts above*) And we all some fools even read it.

Almost closed regarding matter... but you discuss entropy, and that is part of the energy balance... In other words: the sun plays a huge role on earth, and influences the entropy on earth. The sun can turn chaotic systems to ordered systems (think of desalination of sea water, making pure water from salt water with solar power).

Only regarding matter (and even then we're not 100% closed - think of asteroids, or space dust entering the atmosphere), but as far as the energy balance, we certainly are not a closed system (most of the energy comes from the sun, and we also radiate heat back into space).

Aww... you removed it!