CaptainPanic

Maybe you should better define what you would like to do? If you have a desire to "be a part of a group", then you should search for that... But like with any group, newcomers must prove themselves first. It's like that in grammar school, and it's like that in a professional environment. You may consider an organization like the national society of professional engineers, or something similar (I'm assuming you're American here) - but often you need a degree to be able to join that. Search for "society" and then a description of what you like... maybe it exists. They may have sub groups that organize activities and that have projects. If you are interested in the science, then you must (1) choose which field and (2) decide if you want to join something, or start it yourself. You state that you are not confident that you can organize something yourself, so you must join someone else's project. Joining some other project means that you listen to the project leader of that project (like Cap'n Refsmmat said 2 posts below). It is not a democracy... altough you can probably expect that feedback from experienced people will be appreciated. Projects like these, where anyone online can join, are not likely to have the patience for newbies... so you have to fit in quickly. They also won't take the time to formalize the cooperation - it's online and anyone can just walk in, but also walk out. So, you listen to what a project manager wants, write your code, send it in. It gets reviewed, and if it is good, it is used. Btw, I do not see how this is any different from any professional environment, with the only difference that this is voluntary and open source. Open source however allows you to form a new branch (use all the existing work, and use it for your own plans)... Just keep to the General Public License (like gnu gpl).

The link in the opening post no longer works... Any chance you can retrieve the text from somewhere else?

When criticizing other countries, it is important to look at yourself, and think: "Are we really that much better?" If you can confidently say "Yes, I am certain that our culture is superior", then feel free to explain this. As far as I'm concerned, the "free world" is forcing freedom onto some other coutries... which means it's not free, and therefore it failed before it started. At the same time, the "free world" reduces the freedom for its own citizens in order to be able to protect them. Our governments are more concerned with our life expectancy than our actual freedom. Profit trumps freedom already for several decades... It is also the capitalist world, not the free world that defeated communism... and it is the capitalist world that needed a new enemy. As far as I'm concerned (and sorry if this is considered rude) you're a misinformed person, rigney. You have no idea about the actual statistics. You probably do not know many Muslims. You see only extremes. You use individual examples to show a certain trend, but then completely overestimate that trend. You ignore a billion Muslims that are "moderate" (stupid word - they're just "normal"). Your argumentation is based on emotions, and is in many cases flawed. But worse, your ideas are a direct threat against the freedom we hold so dear, because you distinguish between peoples. It is this type of thinking (us and they) that will destroy the freedom we enjoy. You cannot live in freedom, and have your borders closed. The only way to defeat oppression is to actually live in freedom! We cannot reduce our freedom in order to fight for freedom in order to keep our freedom. A wise person came up with the saying: Fighting for peace is like fucking for virginity. You cannot fight for peace, and you cannot force freedom upon someone. So, I must conclude that the "free world" isn't much better... only less violent... and even that can be debated. I would not go as far as to say that the Muslim world is a better place. I like my own culture too much. But I do not think that the course taken by Western governments against the Muslim world is the right one... and I am fairly certain that it will not achieve any of the goals. I believe that the story goes that Jesus himself said that "You should love your neighbor like you love yourself". In this modern world, your neighbor can come from up to 200 countries. And the world isn't gonna change because you dislike a minority of a particular branch of a religious group in a number of those countries. ... And I always wonder why we fight the Taliban, and at the same time support a similar situation in Saudi-Arabia with hundreds of billions on oil money...

Of course. I think that any excuse will do to fear the left... and it certainly doesn't need to be objective. Facts: Widespread strikes, riots. ZERO dead people. Only material and economic damage. Most people still go to work every day. Current president, compared to previous French presidents, is one of the most right wing presidents in ages. Probably on FOX news as: France lies in ruins. Public life comes to a grinding halt. It's a small miracle that the Eiffel Tower still stands. They are left wing surrender monkeys. Just remember that France isn't such a bad place to live in. They only work 35 hrs per week. They stop at the age of 60. They enjoy 40 days off each year (!!!). Their lunch breaks take 1.5 hrs on average, and they eat good food during that lunch break, sometimes even with a glass of wine. And still it is among the richest countries in the world. Conservatives may not like those surrender monkeys - I personally draw my own conclusions. I like that country.

Apologies for not having read this entire thread. Just quickly giving my opinion on this: Changing parties: sure. Should never be a problem for anyone. Changing parties in the middle of a campaign - should be impossible, because someone signs up for the elections as a representative for a party. If the person wishes to change, the only option should be withdrawal... and then this person can try again at the next election - for a different party. How is the general public supposed to know what a person stands for if they change party halfway through a campaign?

I vote for the spider. If it has been that close to the nest for a while, then apparently the wasps do not see it as a threat. Probably no smells originate from the spider, like from mammals... the spider definitely doesn't cause any serious vibrations (to the house, or the air). In fact, I wouldn't be surprised if the wasps are completely oblivious to the existance of the spider. They may not even know it's their neighbor at all. What types of senses do wasps have to detect anything as a threat? I doubt that they can use their eyes for an identification of an enemy. The only way the wasps will ever win is by teamwork. But it seems to me that the spider will take the wasps on .

A sphere with a door in it, so that we can leave earth for some explorations. We can talk about it... but it's probably just as useful to watch star trek. They have an episode about the Dyson sphere - a sphere around a star.

jackson33, I did not claim that France is either right or left. I just gave a view which was different from that of Pangloss (who tried to imitate Fox News). You seem to assume that everybody who is rioting actually does this for the same purpose (namely the retirement age), a point which cannot be proven. I strongly believe that the most violent riots have little or nothing to do with the strikes that are coordinated by the unions. Widespread destruction aren't very good for negotiations... also in France. But, that said, a normal (annoying, but peaceful) strike is a right that the French enjoy to the fullest.

I do not think that the actual position on the left-to-right-scale has anything to do with it. People are losing something, so they protest. Doesn't matter whether the country is left or right. People don't compare their situation to that in other countries, they compare their current situation to the past, and to the expected future. One major difference between France and other countries is the power of the labour unions... They are able to organize themselves quite well, and the people have the motivation to be a member, and to join in protests and strikes. In other words, I think that the scale of the protests can be attributed to the organizational skills of the unions.

It would float. If however it would break up, all the individual segments of the ring would immediately fall back to earth... Why not accelerate it so that it orbits the earth?

While all that was mentioned above about the retirement age is true (as far as I know), I believe that a large group of people also join the protest and riots because they simply do not like their leaders. It's a more general protest. The strikes are almost always organized, and almost always have a reason regarding workers' rights, income, holidays or retirement age... But I believe that especially people in the "banlieue" (outskirts of a city) feel misunderstood and ignored by their politics leaders... or even discriminated against. The police is not respected by young people in most of the country, but while people usually just mock the police (with words and jokes), in some areas this becomes a real conflict.

I believe that the OP means that the Romans used the Venturi effect, or some other form applying a dynamic pressure difference to overcome a height (hydrostatic pressure). ... unfortunately, I know more about engineering than about history, and I have no idea about Roman applications of this principle. I did find this: Roman siphons for water transportation A summary of Roman innovations regarding hydraulics I also found mention of an ancient roman pump on some different websites.

We could also assume that the average shantytown dweller lives in a house the size of a cartboard box... at a surface area of 2 m2. With a total land area of the earth of 148 million km2... so we could stack up to 74000 billion people onto our land surface... without the need for highrise buildings. This thread is a little oversimplified... and overpopulation has absolutely nothing to do with the population density of urban areas. We need to look at the arable land requirement - even if we all become vegetarians, we need some space to grow food. We need to take into account all the infrastructure that we need. The space for buildings other than houses (offices, industry). The space for recreation (I do like to leave my basement occastionally). A little space for nature perhaps. And I probably overlooked some categories. Has anyone been able to find data of the total built up area of the world? I'd like to know the area used for buildings and infrastructure in relation to the area needed for agriculture at the moment. Finally - I would like to add that even if we would find that the earth is not overpopulated soon, this does not mean that it won't overpopulate eventually. It will overpopulate as long as we have an exponential growth of the population. The question is not IF, but WHEN it will be overpopulated.

I note that the question was about "science DIY projects"... But at the same time I agree with -Demosthenes-. I guess traveling is the best hobby to (literally) broaden your horizons!

Whoa! You want to build a pulse-jet powerstation The V1 flying bomb was the first large scale implementation of this type of propulsion. Please note that rather than creating a propulsion, you can also drive a turbine with it... so it can work. I think that your marketing department may have to find a catchy name for the invention (The V1 Powerplant probably won't make it popular), but that is something that can be solved later. I would suggest you seriously consider a continuous operation. Pulsed systems will just make your life harder than necessary (you already have enough trouble trying to invent something new in a multi-billion field of research that has been around for 3 centuries). Here you have a link (yes, again wikipedia) about turbochargers, which may do exactly what you need: compress air for a combustion process. Turbochargers have the added benefit that they're powered by the exhaust gases. If you want to build this for a 3 - 5 kW electricity generator, a small car's turbocharger may be just the right size (or even a bit oversized - yes, cars are that powerful - for example 100 hp equals about 75 kW in power). Finally, some funfacts (completely unrelated to this topic): Here is something about how to add two liquid fuels into a combustion chamber (like kerosene and oxygen). You need a so called "turbopump" to get the fuels in... but once it's in, it really moves.

In this picture, I am not sure what the turbine is connected to... And I am not sure what the color green represents. If the color green would be indicating water/steam, and the "heat emitter" is a cooling device, then you have just reinvented the steam cycle. What would the pulse be able to achieve?

Why exactly wouldn't you be able to make it hotter than 6000 K? If you would have a theoretical lens of a square kilometer, and focus all the sunlight of that square kilometer (approx. 200 MW of insolation) onto a square centimeter, I'd say that higher temperatures can be reached (assuming also a theoretical way of immobilizing the vaporized material that is being heated)? Are the individual photons not energetic enough or something? Where is the limitation?

The most fun I had lately was to build my own Van der Graaff generator. I used this website, because all the parts needed (except the electromotor) can be easily obtained... The motor excluded, the whole thing probably cost me less than 10 euro. Bottle rockets also kept me amused while being a student. There's a surprising lot of science behind it, which you can ignore completely if you like

A nice way to get both objective data (if you know what you talk about) or reason to freak out (if danger symbols and names of diseases scare you) is the Material Safety Data Sheet of a chemical. Google will often provide one if you type MSDS (and the name of the chemical). In this case, we see that the oral LD50 varied for different animals from 2200 mg/kg to 6500 mg/kg. If your friend is an average 70 kg, he must digest at least 150 g of bisphenol A in one go to have 50% chance of dying from it. In short, he can probably eat the entire kettle in one go, and survive. That said, other effects, less immediate, are much harder to measure. For example, the Bisphenol A concentration in the water of the kettle... you'd need professional lab methods to measure that concentration. I personally think that the most components (unreacted precursors for the plastics, and for example plasticizers) that are harmful will come out immediately during the first (few) times you boil water. I would recommend to boil water a few times, and throw that away. Whatever doesn't come out in the first few times, probably won't come out at all, since this will work a little bit like diluting those components out of the kettle. The other question that I cannot answer straight away is whether bisphenol A is found in the plastic at all. It is used for polycarbonate, and in some epoxy resins. I don't know the material for kettles.

First you must find out how much power you are focussing on an object (that is not a temperature, but an energy flow). As I mentioned in a reply in a previous post, you have to find the insolation for where you live. That needs to be converted to Watt/m2s (power per area). Then you focus that energy on to a much smaller area (same power, smaller area). Then you have to look up some parameters of the material you try to heat up (probably water). You need to know the Cp value (specific heat). That's 4180 J/kgK for water. You need to know the reflectivity of your materials (tubes, and the mirror itself)... but you can also just assume 50% efficiency (the rest of the light reflects, and is not absorbed by the water)... probably a safe guess. Then you must decide on a flow of water (kg/s, or liter/s)... because if you have no flow, you will heat up the water more and more and more... Now, you have an amount of energy, a flow, a material that needs to be heated, and an efficiency. Your formula now is: [math]P\cdot{\epsilon} = F\cdot{C_P\cdot{\Delta{T}}}[/math] [math]P[/math] = power (energy per second, in Watts) [math]\epsilon[/math] = efficiency (%) [math]F[/math] = flow (kg/s) [math]C_P[/math] = specific heat (J/kgK) [math]\Delta{T}[/math] = difference between temperature of incoming cold water, and water after heating up Please note that you will probably reduce your efficiency as well because of heate losses. In short, because some parts get hot, they will start heating up the air around it, which means you lose energy. If you have no flow of any material (such as water), but instead have just a single sample which is heated up, then the temperature will rise and rise until the heat losses to the air from the sample are equal to the energy from the sunlight. And depending on the mirror, the sample, the air flow, and some other parameters, that can be really hot. On the other end of the scale, if you have a massive flow of water (say, a complete river), then the temperature rise will be very small... You've entered the realm of engineering, sir. And I congratulate you. What you're trying to do (and what I just helped you with) is an energy balance.

What is the main difference between this and a normal combustion engine? It still has cylinders, pistons, and all the normal parts. I do not see why this engine would be much more efficient? I do not understand your remark about 20 times the current drive ability, while using 70% less fuel. Those two numbers are not in agreement... Lubrication of the engine is not a major issue (sure you have to replace engine oil every now and then - just like you have to change the tires, window wipers and brakes). For a little further reading (but by no means meant to hijack this thread), here is a link to another combustion engine with a (kind of) rotary setup. The Napier Deltic diesel engine, used in airplanes and trains.

I am afraid that I haven't really understood what you want to do. So, while I give you some existing examples below, I realize that this may not be what you are trying to do. Maybe you can provide us with a schematic? Pictures work better than text usually. If you compress cold air which is then heated, you're essentially building a gas turbine engine... although gas turbines are often heated directly (by the injection and combustion of fuel)... I don't know how you intend to heat the air. If you also utilize the waste heat from the combustion process, you create a Combined Gas and Steam power process (which runs a gas turbine engine, uses the waste heat to make steam, for a second turbine + generator). But there are many gas turbine engines. For example, airplanes have completely different gas turbine engines. They often use a turbofan jet engine, which has a large fan at the front to move extra air in a bypass. If you draw up a schematic (your first plan), don't lose yourself in the details. All we need to know is which flow of air/fuel/exhaust is going where. We need to distinguish between hot and cold, and high pressure and low pressure. The types of compressors and turbines, and the choice of materials will come only after that.

It is safe to say that different people have different goals in life. The ideal society looks different in different countries (think for example about Europeans who generally speaking like a much larger government while Americans often would rather reduce their already small government even further). It is also safe to say that probably 100% of the world's population would like to have a freedom to think, say and do whatever they want. This kind of freedom is, I believe, just part of being human. That said, it's a fact that many countries have taboos, and people can live with that without much harm. Finally, we should realize that something that one has owned and that was taken away is missed much more than something that one has never owned at all. To take away basic freedoms from Western people may hurt them a lot (although we seem to allow it all the time - I mean the privacy restrictions and security measures Western countries take). But Chinese people never had this freedom, and I would be able to understand if it is missed much less. I'd like to add a disclaimer here: I don't know much about the Chinese culture, so this entire post should be seen as speculation.

Mankind has become more efficient at doing research (automatization in labs, computers, and increased population), at production of goods and argicultural products (automization again)... And we dedicated all that extra time to jobs in management, the financial sector and indeed entertainment. Where we used to require a large majority of our population to produce something useful, we're now so efficient that we can allow some entertainers to become professionals. In our system, that means we're able to pay for it. In addition, I sometimes get the impression that we're all a little decadent. We're happy, content consumers. We're so rich that there is less interest in moving forward... in such a world, it's logical that the entertainment industry thrives. Remark on topic: In the days when I watched cartoons (and some looked a lot like what is now categorized as "anime"), some cartoons were very educational - about space, but also biology. I am not sure that there is a lot of value in watching anime now... but that's because I don't know much about the latest anime

Haha! You lose! You said "water"! :) At the same time, all statements above were true! DHMO is the cause of great suffering and misery on this planet. It left millions homeless only this very year!