CaptainPanic

The fact that everything is governed by the natural laws (it does seem so, also in my opinion) always seems to conflict with the fact that I feel that I am able to make my own choices. Sometimes I think I am only observing myself making those choices.

It is a mistake in the book. (1.38*10^-23 J/K) * (ln(2) * 10^22) = 0.096 J/K.

All options for artificial gravity that simply pull you down, like magnetism or elastics are only useful to give your bone structure something to do (your bones fights this effect, and keep you up). But all other internal organs don't really feel anything, and your blood will for example still go up as easy as it will go down. I think only rotation can overcome this.

About the orbitals... is there are theoretical reason why the orbitals cannot have another geometry, other than the S, P, D and F? I could imagine that if we're looking at a superactinide element that there's a fifth geometry for an orbital. But I am unfamiliar with the quantum calculations that predict orbitals, so perhaps there's a theoretical reason why we file this new element in the category of "superactinide", and not a category of its own?

The original article (pdf) is found at: http://arxiv.org/ftp/arxiv/papers/0804/0804.3869.pdf Of course with a new article, this was also linked on the website that insane_alien posted.

I agree with iNow (#17). Solar power and batteries (or another energy storage) are a perfect option. The benefit of having electricity and storage is that you can generate the power about everywhere on earth. Independent energy supply is important, and will be more important in the future. Therefore I believe that using volcanoes will not be a proper solution for everyone, although I think it would be a wonderful solution for many... I don't like nuclear power because I have yet to see the final solution for the waste it creates. Higher thermal efficiency is all nice, but it is the same argument why the world is building new coal powered plants. It's only an increase of 60% or so (impressive, but solar is doing better when seen over the last two decades). I'd like to see a higher efficiency in fuel consumption. It's been speculated that the new fourth generation nuclear powered plants can do this... but none were built so far... Therefore, the waste generated remains the same problem it has been for some decades. We're only beginning to permanently store the waste from the sixties (it has been in temporary storages for a while now). In fact, we're still paying for the storage of the energy of the sixties. But my main argument against nuclear is not a financial one, it is the fact that no human made structure has survived more than about 5000 years. Storage is all nice, but I don't believe we're capable of building any structure that is indestructible for the next hundred millennia.

I found this in a 2 min google search: So, at least 3300 years BC people were wearing hats. http://en.wikipedia.org/wiki/%C3%96tzi_the_Iceman And also: http://www.hatsuk.com/hatsuk/hatsukhtml/bible/history.htm (which is not a particularly impressive website, because there are no references)... but I'm not going to conduct a long literature research about hats. I suggest you study the old Egyptians. They lived in a hot place, and they have a long history. If you can find into about their work ethos, and perhaps some info about the schedule (did they work in the hot sun?)... I'd be interested.

I'm glad insane_alien went through it again (I wonder why though). Anyway, I'm pretty sure you consider nomadic desert tribes as a bunch of wankers, but they actually wear woolen clothes to keep the heat out. Go study heat and mass transfer. I think this thread should be closed soon.

About the price of the land: I think the best way would be to make 1 part where the water level goes up, and one where it goes down. Then you do have a max. 20 meter water level difference in the middle, but the length of the dam (which is more costly) can be minimized. I was assuming to use existing lakes, and to build a dam around them. To be honest, I simply assumed that the price of the land is roughly equal to the price of a lake with newly built dams. The reason I assumed this is that a large portion of the land in the Netherlands is actually reclaimed land, and it was a lake before. Therefore, a piece of lake with dams imho should not be more expensive. Regarding fish, sorry, haven't thought of them. Perhaps with some filters (fine nets) you can save them, and make some extra money from growing fish? This might turn into "growing seagulls" pretty soon though. Regarding pumps/turbines. You're right, I should take an efficiency into the equation. I would assume 80 or 90% efficiency. So, between 64 and 81% efficiency in total (water goes through twice). I don't see any problems with the low head requirements. Thanks for all replies.

The few seconds of the clip are the intro of a cartoon. I am not sure that the "air gear rollerblade thing" actually exists. Just to make it clear, we're discussing the thing that is in the pictures below, aren't we? p.s. If you want to make a cool movie with a loop (I think it's a .gif), I can't help you, but Google might help. If you want to extract info from a movie in youtube, I suggest using the pause-button. Copy-paste the picture of the movie is done (in Windows) by pressing ctrl-print screen, then opening MS Paint, and pressing "paste".

It's quite common in Europe. People takes these trains to go on holiday. In case anyone has plans for the near future in Europe: you can book your trip here: http://www.dbautozug.de/site/dbautozug/en/start.html Another train which takes loads of cars: the eurostar train connecting the UK to mainland Europe. (Was already mentioned in replies 6 and 7). I agree that the other side of the Atlantic should be using the train a bit more!

I certainly wouldn't want to mess around with a supernova in my lab. (I get nightmares if I think of all the forms I'd have to fill in regarding the safety issues).

In fact, they generally use numbers with the right units, which is almost unique on the Discovery Channel

You sound like an excellent engineer. Also your remark that you understand math better, and it makes more sense when it is applied in physics make me conclude that you are prime engineering-material. How to get through the first couple of years is going to be the tricky part... it was the same for me... Just accept that you might not be the best student in math, and perhaps you'll have to take some exams again. At least in our system it's no shame to fail an exam. (Actually, the average engineer in my old uni took 7 years to complete the 5 year course. That was not because we're all dumb)...

I'm glad someone is pointing out the greatest stupidity of using a football field as a measure for area: they actually all differ in size. (Just like elephants are not all of equal weight). (Football is the game played with feet and a round ball). At least Boeing 747s can all be expected to be the same length: 70.6 m, (apart from the 747 8I which is 76.4 m).

That's the 3 cent margin I want on each kWh. kWh prices are between 11 and 20 cents in Europe. I am thinking that 3 cents would perhaps be acceptable for producers if they have to choose to shut down or sell at a price 3 cents lower than the market value. I see many windturbines that are not working, and I can imagine that the owner wouldn't mind to let the turbine work even though there is no demand... temporary energy storage could buy this energy at a lower price and sell it during peak hours (for example between 18:00 and 20:00 in the evening). Right now, the gas turbines can be switched on and off quite fast, and there is not a lot of wind and solar energy, so there is actually no problem at all, and no demand at all for any storage. But I hope that wind and solar will be increasing a lot in the (near) future.

I know it is normal technology in areas with natural differences in height: hills and mountains. It doesn't happen in a completely flat country like mine (yet). I am trying to prove that you don't need a hill to store energy with this technology.

Ok, here's a lot of numbers. I'm sure you can all find comments. I am very interested to hear them. My idea is to make an artificial lake with a water level that goes up and down to store energy. We need to smooth out the differences between electricity production and consumption when we want to use. I've always heard that it's economically not interesting, or perhaps not even technologically feasible. I've done a simple back-of-the-envelope calculation to start some discussion. Please comment The artificial lake Area: 1 km2 10 meter deep (average), Total height = 10 meters Total volume: 1000x1000x10 = 107 m3, or 1010 kg. Height of the water = 10 meters max., but on average only 5. Energy storage = m*g*h = 1010 * 9.81 * 5 = 500 GJ Costs 100 kW electric engine = €10000,-- 90 kW pump (connected to 90 kW electric engine) = €7200,-- to 10600,-- So: 100 kW pump+engine costs 10000 + 10600, let's keep it at € 20,000 .-- (So: a 1 MW pump costs 200,000.-- (source: DACE price list of equipment, not online, sorry) 1 ha of land in the Netherlands costs about € 37300,-- and prices are lower in the north. (it’s assumed that buying a piece of a lake and building a large dam around it is about the same price as the land). (http://www.lei.dlo.nl/nl/content/agri-monitor/pdf/dec2002prijslandbouwgrond.pdf) Dimensioning Assuming that the storage should be for 2 hours, we can determine how much energy can be stored (and if this is reasonable). 500 GJ/ 2hr = 69 MW during 2 hours. Total costs 1 km2 of land is 100*37300 = 3.73 million euro. 69 MW of pump capacity = 13.8 million euro Total: 17.5 million euro. Margin on electricity stored is: 3 cent / kWh = 8.33 euro / GJ - (this can be one of those major discussion points that never has a conclusion) So for 500 GJ, this is € 4,150.-- per time. Pay back time Payback time of 20 years: So, during these 20 years, the lake should be filled / emptied 4216 times to recover the investment of 17.5 million euro (interest and tax not included). I have no idea about interest and tax, but let’s just double the costs: 35 million euro. We need to fill the lake 8400 times. This is 1.15 times per day. If this would be used to smooth out for example solar energy (which has a peak and a no-production time about once a day, assuming that the sun keeps doing what it’s been doing for the last 5 billion years)… this seems to have potential. Can anyone tell me if this is unrealistic? If the filling/emptying of the lake can take more time then less power can be stored, but those sources that can store are being served for a longer time. This reduces the need for pump capacity, making it all cheaper. Pumps are the big investment. Even in a densely populated country like the Netherlands, it seems like the land is not the main cost.

The sunshine on a hot day can actually make your head hotter than 37 degrees (the outside of it: your hair and skin). In that case a hat will not keep your body heat in, but in stead it keeps the outside heat out. The temperature gradient is reversed and the hat keeps you cool. This is also why desert nomads wear thick clothes.

Thanks! That's the level of complexity I was looking for... You gave me a simple explanation, and also a few "new" (to me) keywords to continue the google-research Funny that I never knew that a coil is also called an inductor.

The molar mass of glucose (see: wiki, or calculate yourself) is 180.16 g/mol You have the amount in g/l (µg per ml to g/l should be easy). You know how many g/mol glucose is. So, this enables you to calculate how many mol/l (M = mol/l). Then to go to µM is easy again. The important bits here are the units (g/l, g/mol and mol/l) [math] g/l * mol/g = mol/l [/math] However, the molar mass is not in mol/g, but in g/mol. Don't panic. In stead of multiplying, you need to divide by the molar mass. [math] 1 / (g/mol) = mol/g [/math]! So, the first thing you must to is convert all your numbers to the right units (only containing "g", "l" and "mol", and no "µg", "ml" or "µM", then do the calclation, and then convert the result to the unit you want (go from M to µM).

I'm recently trying to pick up some knowledge about electrical circuits, and one concept that keeps coming up is the "electrical impedance". No matter how much I read about it, it doesn't seem to solidify in my head. Can anyone say in layman's words what it means? I have read the wikipedia, and some other articles, so I was hoping that someone could explain it to me without using mathematical terms. Is there any way I can see impedance with a simple experiment at home (using basic electric components: resistors, capacitors, (AC) power source, etc.)?

I agree... although that might not be very easy to understand. (The equilibrium constant being in the order of ten to the power... a lot, meaning that not a single molecule of the reactants remains, or not a single molecule of a product is formed). Just a theoretical question, and perhaps not very chemical: is a nuclear reaction reversible?

A real life example of an equilibrium is water. In water (which is everywhere!), there are reactions going on all the time. [ce] 2 H2O --> H3O+ + OH-[/ce] and also the reverse reaction: [ce] H3O+ + OH- --> 2 H2O [/ce] These two reactions are "in equilibrium". It means that they are both equilly fast, and the net effect is that the [ce] H3O+ [/ce] and [ce] OH- [/ce] concentrations are not changing. A reversible reaction is a reaction that can proceed in both ways. This means that equilibrium reactions are reversible. A reversible reaction: burning sugar (glucose). Your body is doing that all the time, but it will also work using a lighter [ce] C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O [/ce] Plants however are capable of the reverse reaction. [ce] 6 CO2 + 6 H2O --> C6H12O6 + 6 O2 [/ce] The "activation" they need comes from the sun. Plants need light. the funny thing is that theoretically you could see the reaction where you burn sugar as an eqiulibrium... but the eqiulibrium lies all the way on the side of the CO2 and H2O... so the eqiulibrium constant is a HUGE number: Constant = (product A concentration) * (product B concentration)/ ((reactant A concentration)*(reactant B concentration))

I agree: you first play with high pressure (the hydrogen that makes the bottle go boom), then with explosives (once the hydrogen is in the air it can explode in a secondary explosion) and if that wasn't enough, the NaOH is indeed very nasty stuff that will cause you to have scars wherever it touches you if you don't wash it off immediately. And if it gets into your eyes... actually I don't know for sure what happens, but I can imagine you go blind. If you wanna play with bottles that do interesting stuff, let me recommend the bottle-rocket. Also make sure to check some youtube movies about bottle rockets (there's lots of them).