insane_alien

our species has only been around for 200000 years. and vertebrates are much much older than 55million. all the dinosaurs had spines and they died millions of years before 55million years ago.

http://en.wikipedia.org/wiki/Current_sea_level_rise yep, at about 2mm/year i know its wikipedia and lots of people are likely to go 'its only wikipedia, half the stuffs wrong anyway' but this article is quite well referenced if you care to look.

don't really care. i use linux 99% of the time anyway.

could be trashed files and shadow copies maybe, windows is good at hiding that stuff from the average user. me: 'wtf since when did i get 15GB of temporary files?' vista: 'no you don't' me: i'm looking at them right now vista: lalalala

stay travelling at the same speed. of course the only way i can think of to reduce the mass of it by half is to chop it in half.

right, first off, can i suggest to the mods that the discussion between louis wu and myself be moved to another thread, its offtopic and about to completely fail to get back on topic. http://www.world-nuclear.org/info/inf75.html read this. known recoverable reserves ar about 5.5 million tonnes of natural uranium. if we consider unknown sources you could probably expand this to 10 or 15 million. but we'll just deal with 5.5 million as its the known reserves and doubling or tripling it doesn't improve the situation much. Now, the current rate of usage of natural uranium in nuclear power is 65000 tonnes per year. at this rate of usage we have 84.6 years of reserves left not counting new plants or even current reprocessing. when i gave the value of 4 years, was in reference to changing the worlds energy supply completely to nuclear and not changing our utilisation habits. nuclear is at roughly 5 percent of global energy production, so if we only had nuclear we'd be using 20 times as much. thats 1.3 million tonnes per year. at that rate global reserves last 5.5/1.3=4.2 years. are we done now? remember, i'm not counting wide deployment of breeders or alternative fuels, just basing it on our current habits of nuclear fuels and known reserves. so, i'm not saying this a hard limit and its not, there are many ways to get round it(one of the most immediate would be for the US to get its finger out and start reprocessing and for everyone to start burning plutonium as well) but these aren't happening now so if we were to immediately convert over to nuclear we'd have 4 years of useful fuel. maybe 12 with currently unknown/uneconomical deposits. your turn.

because they are lying. it really is quite simple. steorn do not have a reputation of being honest.

http://www.scientificamerican.com/article.cfm?id=how-long-will-global-uranium-deposits-last given current usage rate of nuclear fuel without reprocessing or breeding, that source says we have 230 years. but thats only for 5% of global energy. with 100% utilization we have 11.5 years (the 4 year source is using only discovered sources) the breeder reactor and thorium reactors will be absolutely necessary if we need to switch to nuclear. you can't get away from it. the reason it is so low is because only over 99% of the uranium is not fissionable without putting it through a breeder. i'm not grossly underestimating reserves, i'm saying that without breeder technology, offloading a significant portion of power generation onto nuclear would be disasterous and short lived. with breeder reactors and thorium reactors, the fuel would last millenia.

i've never actually asked them but we have ahd conversations about various terrorist attacks as i imagine many people have which lead to conversations about islam. just because i know a fact about someone doesn't mean that i just went up to my friend and went 'oi! towelhead! do you think we're going to be sent to hell for not believing in your god?' that would be polictically incorrect. not that i hold polictical correctness highly at all.

ajb, there are similar passages in the bible, torah and well, pretty much any and every holy book there is. i know a few muslims(about 10) precisely none of them are violent and think that non-belivers should be punished. they all seem to have got the message 'peace to all mankind' from the qur'an. and many of them are very religious to the extent that half of them have taken part in the hajj pilgramage. some more than once. as with all religions however, there are a few select nutjobs who draw attention to themselves by being complete prats. it happens in every group of people. i'm of the belief that most muslims are genuinely nice people and that it's only a minority that are being pricks.

i suppose it could reffer to jerk as well. as in increasing the rate of increase of speed. just someone being careless with language, not a contradiction in its self.

don't limit your responses, just think them through a bit more. everyone comes up with ideas that seem good but 99.99% they turn out to be crap if you think about them for a bit. it happens to you, it happens to me, it happens to nobel prize winners, everyone. don't limit a thing, just think about things some more and there will be something more interesting to talk about thwere there may not be an obvious right or wrong and a nice good arguement can follow. for instance, the space elevator idea isn't entirely without merit. it would be the perfect launching platform for massive solar arrays that could supply us with energy in the future. and carry us on to be a type I civilisation on the karashdev(i can never spell this name) scale. but its not likely to be used to house nuclear plants. and its a more likely to be a century down the line than soon enough to limit global warming. but there is merit for future environmentally friendly energy production.

the dark tower series by stephen king. i've read all 7 books i don't know how many times and now that i've thought about it again i might just have to do it once more.

depends. the molecules could effectively immediately be converted to energy or it couldd hang around in there for decades(although that is unlikely). you can't really approach the problem by following an individual molecule, you need to take a statistical average of many individual molecules to get the residence time. just take the number of glucose molecules present within the cell and divide this by the rate at which they are consumed. this should give you an average residence time.

Angryturtle, we have exceeded the breack even point in fusion technology, but it was only just. ITER planns to do it with self sustaining plasma(can be run indefinitely) at a low net energy gain but be able to go higher (but not sustain it indefinitely). after ITER has researched suitible materials for reactor linings then DEMO will come about and finialise the designs for commercial reactors.

1/ why would it create any CO2? surely energy production would be solar in nature else why do it in space? 2/ this would cause some worrying mass balance problems. if you are generating significant quantities of CO2 up there then you'll need a few large pipes of oxygen and carbon up there. just means we're going to be losing oxygen and spending a fortune(albeit a smaller fortune than if it were launched on a rocket) transporting mass up the elevator. if you have went to the trouble of a space elevator then superconducting cables are the likely choice, microwave beaming for all the unattached power satellites. but this is besides the point, a space elevator could not be accomplished in the near future without massive and total international cooperation and spending. not to mention the resources it would consume during construction would cause deficits in other areas. our industry and economy aren't up to the task yet unless we have a 'build one or face extinction' scenario. we are not yet that deep in fecal matter. no, it'll still produce just as much waste, all it would do is provide a potentially disasterous place to store it. much better we just bury it deep and seal it off. examples are the oklo natural reactor. this thing was dirty as hell and in contact with ground water and so on but it doesn't seem to have destroyed the environment there. where we want to bury the waste is safer than that. more coolant would be needed. space is cold, but exceedingly hard to dump energy into. you'd need MASSIVE radiators and they need to be out of direct sunlight or they won't work very well. now there's a crap idea. do you know how much fuel you can recover from those things? thats like saying we should change the way we extract oil to taking a drop from every barrel send it off for processing and dumping the rest into the sea. reprocessing would be far better. or we could just switch to non-CO2 producing energy infrastructure. like nuclear. we have plenty of fuel as long as we make breeder reactors (4 years if we don't). not only that but there are also renewables such as wind wave and solar. CO2 sequestering from large plants both power and chemical(it isn't feasible to extract it from the atmosphere, its too low in concentration for that). chucking everyting into space would just create different problems. what we need to do is learn to balance it all. and we can do it in both and environmentally friendly and economically friendly way. the technologies just need a few more years to mature.

just heat. the thermal expansion can be quite large due to the length of the lines.

yes, i know that, but you can spin a sphere faster as it has more structural strength.

right, using some very simple algebra, it is easy to see that the energy density for a thin disk is E/m = (r^2*omega^2)/4 i have kept it as /m instead of /V as these are directly proportional and keeps a density term out of it. it is a similar story for a sphere as well. Energy density is proportional to the product of the squares of rotational velocity and radius. this means that it is very possible for a large object to have the same energy density as a small light rapidly rotating object. infact, after some back of the envelope calculations (the equations for moment of inertia and rotational energy are trivial and well known, the data for density of steel(iron) and volume of the earth along with rotational velocity are also readily available) i found the average energy density of the 0.8mm steel ball to be 5.84*10^6 J/m^3 the earth averages 1.981*10^8J/m^3 earth wins due to its massive mass.

well, i'll be down the local pub for the bells, when we get kicked out of there then i'll probably go to a party that'll last until dawn or so then i'll go to bed for a few hours and then get the traditional steak pie for lunch watch tv till 9 and then go to sleep. after that i have a lot of studying to do for my exams.

while an excelent idea in theory, in practise its going to result in a bunch of people asking the same thing over and over and over and over and over .... you get the point? it would swamp out anything interesting with cries of 'how do you do question 2?' there are forums dedicated to helping people with various examinations, they would definitely be better set up to deal with them as that is their specific purpose. study help is just something we do on the side. not to mention, this is an international forum and not everybody here undergoes the same educations system. even with GCSE's thats just england and wales. not even the whole UK.

pressure is how the force is transmitted to the water. force over the area of the paddle.

modern ciphers actually get round that quite easily. a statistical analysis on a peice of ciphertext will usually reveal all characters to occur more or less equally. for instance, -----BEGIN PGP MESSAGE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Use GnuPG with Firefox : http://getfiregpg.org (Version: 0.7.7) jA0EAwMCyuyUECcbNb5gya5as+CejqRsZ5HpV8nZGWNs9s/2idUc150AJru9FKcc 1ClyQygn6I5X30AqBUZ3su94bYJWWOvX6rqvZ1KJ1/zfcfRpb+0m2AoHQ56qRAJV PdEEwzCEfBikV5CClrt93cNsPEz/vjj7kPtHWd4vJaZAnfKwVMSeDsLq+N5pxXT3 jitunlPPRFx+gSlQFsgwCnXM+5v7hZDkhR4DmuqZA42WUwSoBBjaMkRFbkg3Ju8= =DaRc -----END PGP MESSAGE----- this is your post encrypted using firegpg's symmetric encryption(not sure what cipher it didn't give me a choice, AES is my guess) and the key is 'key' so you can check it and see if you want. the only way to break that encryption would be to bruteforce it if you knew the encryption method. and as the key is short, it wouldn't take to long either.

it doesn't have a vapour pressure equal to that of the atmosphere. at room temperature it is roughly 4kPa while atmospheric is typically 101kPa. it evapourates because very often the partial pressure of water in the atmosphere is less than the vapour pressure of the water. this is often reffered to as humidity. if the relative humidity is 100% then the water will not evapourate as the partial pressure and the vapour pressure are in equilibrium, but if the helative humidity is lower, say 50% then the water will evapourate until it is either gone or the humidity is again at 100%

Justonium, big things hold energy easier because they don't have to spin as fast in order to hold that amount of energy. to make this example very very clear i'm going to take it to ridiculous levels. lets take the earth, the centripetal acceleration necessary for it to hold together is quite tiny, so it could happen without gravity. if has a LOT of energy stored alothough it is rotating quite slowly. if i were to take that 0.8mm diameter ball at 23million RPM what do you think its energy is in comparison to the earths? if you thought 'not much' then you'd be right. its true, in theory you could impart the same rotational energy the earth has on that little ball but it would require it to be made of unobtanium and ultrahigh vaccuuums for its storage and all sorts of fancy technological wizardry to be able to spin it up and extract the energy(modern tech is too slow to do this). big stuff can hold more energy. nuff said.