insane_alien

yes, but it would require packing a lot of suspicious looking equipment into the cockpit (or the quicker and easier option of replacing the cockpit entirely) which would definitely be noticed by well anyone as its a job that would take weeks if not months. on the whole, it'd be much much easier to say, take a religious radical willing to die for the 'cause' have him/her hijack a commercial flight and aim the plane towards some big easy to spot from the air target.

We do not yet have a complete understanding of the many many functions of DNA. Whoever told you our understanding was complete was wrong. We know the structure and DNA sequencing is getting cheaper and easier every day but there are some areas on how those sequences are expressed that are not understood at all.

It could not possibly have been thermite detonations (for one, thermite doesn't detonate). second, the common evidence of some red hot liquid flowing out the side isn't thermite, its something liquid and on fire, not thermite. if it was thermite it'd be sparking everywhere and look a whole lot messier. there isn't any evidence of thermite.

yeah, thats a process of melting and mixing rather than just melting.

fluorine has a higher mass than oxygen is one of the reasons

Hal why don't you just use 'liquify' instead of melt? the process of melting is nice and defined while liquify is suitibly vague to encompass non-reversible processes. also for the non-reversible liquifying processes, they probably already have names so there is no need of adding another into the mix. but as to normal thermodynamic phase changes, melting is and always will be, reversible.

ammonium nitrate is water soluble. just wash it off with plain old water. there is little risk of detonating it, you need to put a bit of directed effort in to do that.

its when an insulator fails to prevent the flow of electricity. lets say you have two electrodes sandwiching a layer of rubber. apply a voltage and you won't get any current because all the electrons in the rubber are tied into the rubber molecules tightly and they can't move. as you increase the voltage across the rubber the electrons will get pulled by the electrostatic force more and more. eventually you'll reach a point where the voltage from the electrodes is enough to rip the electrons from the molecules and let them free to move. When this happens you get a dielectric breakdown. its typically a cascading avalance like effect, the first free electron knocks a second electron off its molecule and then you have two, those two each knock an electron off etc. etc. once you have this flow of electrons, the voltage will drop sharply and you'll be able to conduct electricity through the insulator at a lower voltage than the breakdown.

while i don't know for sure, GTA probably was made using C++ you can make games in any programming language you want. C++ happens to be a common one.

blender would be software of choice i believe (a few movies have been made with it)

Wind turbines are the shape they are because of over century of propeller design, aerodynamics and the advent of computational fluid dynamics. vintage windmills were based on the aerodynamics of sailing ships. there is a big difference in knowledge now, we can optimise for the most efficient shape rather than guessing a bit.

what he built is nothing like a nuclear power plant. thats like saying someone who made sparks in their kitchen with some flint rock made a complete functioning 2GW coal fired power plant.

how is it different from a birds nest? most people would classify a birds nest as natural.

nuclear fission is a nuclear reaction. you are changing the substance. That cannot come under phase change (although the daughter products may be in a different phase from the parent) as the substance after is different from the substance before. I don't see how this makes the logic circuitous

Oh, I didn't think you were really trying to argue that. It seemed a bit too self evident if we start from the safe assumption 'melting exists'. Of course melting can take place without you having to prove anything. You wouldn't refreeze some icecubes everytime to prove they melted.

I'm not sure what the issue is then, you don't need to show reversibility, you need to show the liquid is the same substance as the solid phase. now, of course you don't need to do this every time, its commonly known that ice and water are the same substance just in different pahses, but for a new material you might have to. also, freezing the material again to show that the change is reversible is just one of the ways of proving it is a phase change rather than a decomposition. it is not a necessary component. its just that if it is a phase change then the change can happen both ways as a result of thermodynamics. if it can't happen then the either the laws of thermodynamics are ridiculously wrong or it wasn't a phase change. and you know how well tested the laws of thermodynamics are. The key point is that the substance remains the same at a molecular level. reversibility is just a result of that. I think i'm putting the point across poorly. Take gravity and orbits. If there is gravitational attraction then orbits are possible. you don't have to show there are possible orbits to show there is gravity, but this in noway affects the possibility of orbits. like this, you don't have to prove reversibility in a phase change but its still going to be there as a result of the nature of phase changes.

I think you are getting the definition a bit backwards because of discussions that went on in the last thread. reversibility is a logical conclusion of the fact that the material doesn't change at a molecular level (only intermolecular bonds are disrupted) so by taking energy out of the system, it should go back to its initial phase. phase changes are defined independent of reversibility but reversibility is an inherent property of a phase change. For instance, water can be defined independently of wetness but wetness is an inherent property of water (at least in its liquid state.) in the last thread the only reason reversibility came into it was to show that the 'molten' wood was not actually wood but something else entirely which meant that it was a decomposition reaction rather than a phase change. I think this is where the confusion is coming from.

just to be clear, a lot of the news seems to be passing on the impression that this was a fully working nuclear reactor as in the type that can create a self sustaining reaction. it wasn't He built an atom-smasher type nuclear reactor. still very cool but nothing to worry about really. I think the term reactor may have come from translation although atom-smashing is a nucelar reaction. It's quite simple to do what he did (don't let the term nuclear confuse you). All you need to do is get a fissile target, even a rock of uranium ore would be sufficient, and fire some neutrons at it. if you monitor it with the right equipment you can measure the increase in radioactivity caused by the atoms fissioning. I imagine his set up was something like this from the new stories the americium from the smoke detectors would have been combined with some beryllium foil to create a neutron source. infront of this he would have had his fissile target, could have been a shard of depleted uranium although there are more common fissile materials such as thorium he could also have used. and around the target he had some geiger counters to measure if he was creating any fissions. Interesting experiment, but one that is done in universities almost everyday. he's being arrested for illegally possessing a quantity of radioactive materials above the legal limit.

as long as you prove the liquid material is actually the same substance it was before it was melted then you don't have to show that itis reversible because if it works one way then it will work the other. if it isn't the same substance when it is in the liquid state then it isn't melting. phase changes are always reversible

wood doesn't really factor in to it. phase changes are reversible processes that can be performed by the addition/subtraction of thermal energy and/or pressure. if said process is not reversible under addition/subtraction of thermal energy and/or pressure then it is not a phase change, it is a reaction. the reaction may result in products of a different phase but it is not that the original substance has changed phase it is that original substance is not there but a different substance in a different phase has replaced it. think of burning some petrol you haven't turned the petrol into gaseous petroleum(evapouration), you've turned the petrol into CO2 and water vapour. its not a phase change but a reaction.

if the ice 'melts' and is suddenly no longer composed of H2O molecules then it wouldn't be melting as there is a reaction involved that is more than just a few intermolecular bonds. this is what happens with wood. you can get it to change phase but in the process you are destroying chemicals and turning them into other chemicals so it is not just a phase change and hence, not melting. my usage of the refreezing was meant to show that it must still be the same stuff in both the liquid and solid to be called melting as phase changes do not involve chemical changes, only structural. Lets take sodium bicarbonate, if you heat this you can end up with a liquid (if you do it slowly then you won't even notice the gas being given off) and then if you allow it to cool you'll end up with a similar looking solid. however if you pick it up you'll get caustic burns as its now sodium oxide which will dissolve to form sodium hydroxide. so it wasn't just melting. there was a decomposition reaction along the way and you can't get the sodium carbonate back without further reactions. so you get where we are coming from now?

no, but the fact that it was the same afterwards (minus shape) validates that it was indeed a phase change and not a decomposition reaction.

this is only possible because of the layer of nickel fluoride that forms on the surface and creates a passivating layer. Fuorinated plastics like PTFE would also be reasonable containers as they have low reactivity.

I for one find this hilarious. Particularly the 'hip' part. Not that english speaking countries are immune from using other languages in advertising to achieve a certain appearance. I'll be buying a machine washable suit next time too. I hate the dry cleaners.

just use the basic dilution formula: C1V1=C2V2 where C denotes concentration, V denotes volume 1 denotes initial condition and 2 denotes final concentration. rearrange to suit the situation.