Comandante

there's some truth in that too. though the only reason how i see that could work is if you were seated in a special position relative to the fan, because as the cold air goes up the warm air will come down and so even if you were cooled by little cold air, you would get warmer again (and i would assume the air would very quickly get mixed anyway so this would only work for a short time). besides, you're sitting on the bottom of the room, not in the middle or anywhere else - meaning that you are ALREADY in the colder part, and considering that - why would you want to get the warm air down on you anyway? unless it was winter or something .. so really, the only way I see how a fan can cool a person is by inducing faster rate of perspiration. what' im curious about tho is whether there is any "heat loss" or heat transfer from one area to another as a result of low pressure.. but seems like not many have the answer

I've heard of that somewhere, once upon a time... I might check it out as you said, but not soon, quantum physics isn't my first preference

That is very likely indeed. But can you explain to me this; Say at the moment we are only able to produce distribution of possibilities as you call it for the possible paths an electron can take. Is it true that if you're coming up with 'probability' (each possibility has its own probability?) for something to occur there are things/factors you can't account for which can affect the outcome of your experiment? In other words if you are unsure of which path the electron will take how could you be certain that it can never be known? Isn't that like having a reaction without an action?

I'm not a big fan of Einstein but I'll have to go with him on this one - in my belief God did not play dice, even the movement of electron can be predicted as I don't see how there could be such thing as random or ‘probability’. The thing that swansont mentioned about distribution of probabilities I see as nothing more but a sad fact that we formulated a law that only partly describes the movement of electrons - and that's probably because we can't account for the rest of the factors affecting it. Entanglement might hold the answer. If we knew everything there was to know about the universe then we would theoretically be able to predict everything that was about to happen. The only problem is that we probably wouldn't have sufficient computing power to do so as the number of factors would be huge with a capital H. I am also not a big fan of the uncertainty principle - my 6th sense is saying that it's not quite right I like to think that not everything is predictable for that would mean that we can make a choice, but the logic is somehow dragging me away from it and it more and more seems that there really is what some call destiny, but then again this leads me into Matrix philosophy and I’m tired from that.

the same question i've been asking myself, only i've been using a dice , the dice seems to be rather popular. have a box in space, vacuum inside, have a magnetic field or something else technologically advanced enough to hold the dice in exactly the same spot twice, drop it against gravity to the bottom of the vacuumed box and you get the same number twice? perhaps the probability of getting the same number twice would be 99.9999999998 or something due to the effects the dice would have on the box the first time you threw it, but you would still get the same number? how would you know that the probability wasn't 100%? you'd have to repeat the experiment until you get it wrong, but the more times you repeat it the less of a same box you will have, so basically it's not the same box anymore as it was 50 tries ago.... but think of this, if you had 1 million boxes that were exactly the same and the dices were in exactly the same positions and dropped against exactly the same force of gravity you could eliminate the problem of having to think about which particle moved as the gravity-powered dice hit it. you then inspect 1 million boxes and you find they all produced exactly the same number, how would you still know that the probability is 100%? that's the part i don't get, how can you ever be sure the probability is 100% when there's infinite number of times you can repeat the experiment?

swansont, you're referring to the room as a whole or just part of it as I am? Because if referring to the room as a whole of course I think the total amount of heat energy would be constant (or in a constant rise you could say due to heat generated by the fan and other devices) provided good isolation, but what I'm curious about, perhaps didn't stress it properly earlier, is the air coming out from the fan blades at the front and say few meters ahead. My idea was that the air would come out slightly cooler (the heat energy from the air being absorbed by the blades perhaps? then later being emitted back into the room etc -> flow of energy) - ignoring the idea that the air would Seem to be cooler because you would feel cooler (speaking of this I can say I have some understanding, it has to do with conductivity of heat, eg. you're in a room with tiles on one side and wood on the other, they are both of exactly the same temperature, but of course you would feel the tiles to be much colder to your feet as they drain more heat). Continuing on what I was saying, the slightly cooler air would then either absorb the heat off a person's body and eventually mix with the rest of the air in the room. That being only a scenario I envisioned, I still seek the answer to my main question; Does the air cool down as the pressure is reduced around the spinning area and would this be measurable?

hmm, so you are saying that fan generates no pressure change? or are you saying that it does generate low pressure but this does not affect temperature at all? i'll try the thermometer later on, but let's just say the thermometer can't detect such small amounts of temperature change? how would you know?

somebody told me that a decent room fan, eg 40cm one, does not cool air in the room and at first thought this seemed logical and i would've said the same thing, but the question itself made me question it twice. is it really true that a fan does nothing more to air besides putting it in fast motion? I did a quick search on google and I an answer popped up on howstuffworks; http://science.howstuffworks.com/question22.htm They seem to be saying the same thing. But this is what still makes me curious; If we ignore for now that the fan generates heat, let us assume it's just a very efficient fan that doesn't generate considerable amount of heat and all it does is circulate air in the room. Now, considering the shape of the fan you can see it was designed in a way that takes the air from the back and speeds it up blowing it to the front. What I don't clearly understand is how and why this is happening. Is the fan body generating area of low pressure in the spinning part such that the atmosphere is pushing the air through the fan - IF SO; doesn't this then decrease the temperature of the air as pressure and temperature are related - and to what extent? OR; is the fan body simply carving through the air in circular motion such that the air is only 'mechanically' moved from the back to the front - just quickly. I've never read much about aerodynamics so I'm just guessing for that part, but I'm a bit more familiar with temperature/pressure relationship so that's what makes me curious. Anyone got a good answer?

Nice find on springerlink. Chinese work hard on chem eng. And citing the full article here "Bis(2-butoxycarbonyl-3,4,6-trichlorophenyl) oxalate was prepared in advance with an established procedure [2]; alternatively, it is also available from Fluka." you can see that the document shows only half the story, nevertheless I found the "Procedure" section most interesting to read as it tells how everything is done. I concluded however that I don't have sufficient resources to repeat the procedure, so I might just leave it on that for now, unless someone else comes up with another way YT2095; Been there on that site of yours, not bad at all. By the way I tried the yellow+blue dye but the color remained yellowish and with much smaller glow intensity, although it may look bright on this video the green one was much brighter; http://www.youtube.com/watch?v=N-RYZz7UQ8s Did you find that patent yet ?

That's alright. See there goes the popularity I don't think many students would find it exciting to work 5hrs a day for one subject. Also, is this just to get you a pass or are you hitting some high notes there?

Is this for 2 subjects, 5hrs a day, or for one only? In either case that sounds about what I'd expect.

Yes I thought of that too, and did a little research Here I quote http:// www.pcmag.com/article2/0,1895,2023990,00.asp :

That's interesting, considering how many old computers get thrown away - collect all of them and you're rich! I don't know how they would go with extraction but if it was me I'd first try some electrolysis (get some iron and plate it with gold off those parts and then melt it afterwards - just an idea) or bring everything to the melting point and separate things as I go along plastics will melt easily, then aluminium, and then comes gold around 1000°C, iron will stay as its higher than that... Just a few ideas If none of that works, I'd take a metal file and start grinding!

First I agree with the part where you said more jobs This is actually what this doc was saying; Understanding of physics and physical world coupled with maths gives you a BIG advantage for employment (in research). But the reason why he suggested not to do it was that the thought it was simply too hard (I think he had the impression that I was one of those only-biology-loving students, and the truth to be known those are plentiful!), and then after he'd seen I did lots of math in high school and that I really wanted to do it, he agreed, but sent me off with caution! But as far as I'm concerned I'm looking at a pass - at least! Yes I have to look into biochemistry on top of that but I'll cope. And Snail, how long do you spend studying one of these units per semester say, on average day? Give me some stats (for both physics and math if you can) I'd like to have some idea

Really? That's awesome! Is your patent in the online patent database to have a look at? Grrr you did it for free?? Did you at least try to sell it? Well done either way

I don't know about the entire academic population but speaking from my own perspective I'm turning more to physics than to any other subject lately, vastly inspired by other books and documentaries which deal with physics. Having done some physics in high school I found it pretty attractive, then in my first year of biomedical science I missed it! Now decided to use all my elective-spaces for physics but was then advised of its difficulty and prerequisites. Well, so far I've ignored the warnings and took the prerequisites as well (math modelling, calculus and multivariable calculus) so you can see that it is indeed very demanding - which causes it to drop in popularity, but I'll give it a good go nevertheless, and perhaps report in this thread of my experiences after a year or so Just one more thing, when I say I was advised it was very difficult I was also (as a biomedical science student) advised not to do it! I found this quite interesting to hear from a doctor who teaches there but he actually advised not to do it?! Isn't he meant to encourage people to do what they want? And this didn't come from one person, but from a few. Later I insisted so they agreed it's ok if I really want it. I can only hope they were wrong! If physics puts me down with other subjects I am very likely to discourage anyone else from studying it, and this is where pattern forms - why the popularity is dropping.

Agreed with Ndi, and as for physics, the same applies. We can't know how many of course, but there's still many discoveries to be made and we know this because there's lots of things we observe that we can't explain. Eventually discoveries will be back-related to explain our observations of previously mysterious phenomena, but 'til then - the race is on! Just to point an example take a look at "optical tempest" - that's what it's been named. It's some kind of previously-unknown radiation that comes out of LED diodes if I'm not mistaken and until 2002 virtually noone knew about it - at least in the 'open-source' science and yet it was around since the time of LEDs. (It allows potential attackers to use the phenomena to capture the view of your monitor's screen on their own screen to within a decent 20-30m range - information theft- see this pdf document; http://applied-math.org/optical_tempest.pdf - it's research paper). I would guess discoveries are being made probably on a daily basis, most of them kept secret because everybody wants a prize, but eventually one or two surface out I actually thought about this as well - that most of the stuff would soon only be discovered in multimillion dollar labs, but then I hit google and looked for things, and it seems, to my surprise, that the situation is quite the contrary. You see, in multi-million dollar labs the workforce is usually concentrated upon improving existing technology so that they can earn more money from their improvements/patents. New things almost always start off with individuals and ideas, and in a lot of cases from accidents or careful observation - after that, further research/improvement is carried in high-tech labs. That's at least the impression I get based on the stuff I read - research papers etc. By the way YT2095, if you discover something any time soon make sure you post it here

ah, so it's not worth even trying to order then is it i need to find myself a nice supplier here in aus... hard task, easier to just make the stuff if you possibly can.

nice site Miguel YT2095; Don't know if you know of this supplier but I came accross it just yesterday and it seems like they've got retailers in lots of countries, sounds familiar though but I've never heard of it, and they've got everything; http://www.sigmaaldrich.com Check it out if you haven't.

I've heard ammonium nitrate can be used for propellants too but is highly recommended for experienced users. I used KNO3 and it works fine, but as a beginner I found it takes some time to learn proper melting technique (if you use KNO3/sugar) and later making an engine out of that. As far as I remember I think KNO3 is hygroscopic too so if yours was out in the open you might want to dry it a bit as well. I once used relatively "wet" KNO3 and the rocket barely lifted off the ground a few meters, it was flying up amusingly slow

Thanks First mixed 2 different dyes (9,10-diphenylanthracene and 9,10-bis(phenylethynyl)anthracene in about 50:50 ratio (a total of 25mL), then added about the same volume (25mL) of H2O2 into a 50mL flask. I also think that in H2O2 there was salicylic acid as a catalyst. Also, just to comment, I don't think phenyl oxalate was used in mixture with dyes as wiki suggests, because these light sticks were made to work over 8hrs and for that I think they've used bis(2,4,5-trichlorophenyl-6-carbopentoxyphenyl)oxalate (CPPO) (again, as wiki suggests). HOWEVER, I noticed that these two dyes mixed together gave significantly brighter glow at approximately steady intensity for only about half an hour (might not look that bright in the photo but I assure you it lit the entire room so you could read a book under its light, it's just that camera exposure caused the blackness around, the intensity was about the same as that of 2 candles I would say) and for further half an hour showed steady decrease until it eventually was so dim you couldn't see it glow with 60W light bulb turned on in the room, but was nevertheless visible in the dark for another few hours. Also, since these two dyes gave off photons from the same side of the spectrum I'd assume that halped increase the overall intensity but not sure with that. Next I'll try using dyes for blue and yellow in a mix to see if I'll get green light and if the intensity will be the same as with blue and green and how long it will last. By the way, is there a way to test for salicylic acid in the peroxide? ah, one more thing, You can make phenol from cumene - http://en.wikipedia.org/wiki/Cumene if you click on the Cumene process it tells you how (not something I'd attempt yet but perhaps you can give it a go if you have the resources http://en.wikipedia.org/wiki/Cumene_process You can also make phenol by reacting benzenesulfonic acid with sodium hydroxide, as well as with hydrolisis of chlorobenzene.

as for phenyl oxalate I think I might know where to get it from cheap I'll get back to you if I find it but don't think you'll have local retailer anyway.. but I think that's easy to make isn't it? just need ..the ingredients

ah, apart from the basic stuff I synthesized at first year uni I haven't done any other so I suppose I'd have to start with some basic dyes... I used hydrogen peroxide from the shops tho with dyes from the commercial light sticks (my fav 9,10-bis(phenylethynyl)anthracene - at least i think that's the one - for green) and I figured they put something else in the peroxide in the lightsticks, apart from the catalyst, there's something else still as the same conc of peroxide I made doesn't work the same as same conc of peroxide from the lightsticks... anyway, using peroxide from lightsticks and 2 different dyes I did a nice little light-up today in what ended up as greenish glow; see attachment I wish I knew how to make this dye... doesn't seem to float around the net that freely

does anyone have any knowledge about the synthesis of any of the following dyes, or any other fluorescent dyes for that matter that I could possibly make without too much effort and resources, provided of course, i dont get any poisonous gases ; 9,10-diphenylanthracene 9,10-bis(phenylethynyl)anthracene 5,6,11,12-tetraphenylnaphthacene I was previously extracting dyes from the lightsticks but they're damn expensive! (around $1.20 per 20mL the cheapest i got)

hmm...It explains why water has to be responsible rather than some other liquid, and although there is no evaluation on the possibility of a dislodged rock I don't see how a dislodged rock could create such an interesting shape... I haven't looked into it too much but on some other sites you can find higher resolution photo of the actual crater which clearly shows the shape of the path so I would say the rendered image is accurate enough. From what I can see in other articles 'scientists' are fairly certain that it was a result of water flow. Will look into it more over the weekend though. Speaking of water below the icey walls of the crater, would it be feasible to mount some strong nanotech projectile with next Mars mission, drop it off from certain altitute and let it accelerate to the surface of the walls of crater and perhaps punch a hole through it?