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i doubt it. The energy of microwaves is not enough to ionize atoms, as such it is doubtfull that they have any effect (positive or negative) on the chemicals is your body, incuding DNA.

i would try to answer this question, as i have studied it a bit, however, it is clear that glider knows much more about this stuff than i. SO rather than confusing you, i will wait and let him answer it. If he doesn't answer in a few days, i will write what i know

yeah, the way a plasma TV works is like this... IN the TV there are thousands (million?) of tiny wells. IN these wells are placed a chemical that exists as a liquid (or gas, i forget now). There are three types of wells. WElls that contain chemicals that emit red, green, or blue light. These corespond to red green or blue pixels. Then when the TV needs that area to be, lets say blue, it runs a small current through the blue well. This current ionizes the chemicals and they emit blue light. This is the same way that neon signs work, or flourecent lights. It just it is on a really small scale and the emission is quite sharp (meaning that it emits at roughly one wavelegnth).

Well, if you assume that x and y are both numbers, the y devided by x must also be a number, right? Well we don't know what that number is (since we don't know both x and y) so we can just assign that number a variable, let's use k. NOw we find that we have; y/x=k we can then rearange this equation (by multiplying both sides of the equation by x) so that we have; y=kx and now we see why we can make this statement. Really it just stems from the fact that if y is number, then we can pick two numbers that, when multiplied to gether, will give y. THen we call these numbers x and k. That is all. Cool

who cares how fast you can get an answer if you don't understand fully what that answer means?? There is no point to shortening the amount of time required to obtain an answer you don't understand. If you want to get and answer and don't care how it is gotten, then hire a firm to do it for you. Then you don't even have to learn how to punch numbers.

you are missing one piece of information for this calculation to be made. Specifically, you would need to know how long the "jets" are being fired for. If you mean how fast will the spacecraft go if you let the jets fire forever, then it will approach the speed of light (and it will attain the speed of light after an infinite amount of time).

many things in biology (like growth curves, populationi fluxtuations, food uptake, ect) can be described by differential equations. A good way to ensure that people will understand DifEq is to give them a solid background in the calculas As far as chemistry goes, i will speak from experience. Without knowledge of calculus, you will be dead in the water. Unless you want to be some lab monkey that does stuff without understanding it. Or rather i should say, in order to understand what is happening in chemistry, you should be quite familiar with differential equations again. Many of the ideas in DifEq are taught first in calc. marine science deals with chemistry and, hence, needs DifEq again. ALso, the deal with things like concetration changes, population changes, temperature gradients, pH balances, migratory pathways, ect. All of these things require -- you guessed it DifEq. Psycology. Ok, i don't really konw anything about this. So perhaps here is something that does not really require advanced calc. But i don't know enough to say either way. The point being that many things in the world can be described by math. Apparently espicailly differential equations. (perhaps math should be required up to and through differential equations then, really). Thus, if one is to ever hope to have more than just a rudementary understanding of what is going on in the world (and hence, their feild) they should have a good understanding of how math works. Without an understanding of math, you are left with just a fuzzy sort of understanding of how things work. You might be able to make quantitative statements, but you will never understand why you can make them. This understanding if curcial. Your educators understand this and that is why the require math as a general education requirement. Whether you like it or not, math is going to be pretty much everywhere. Having more knowledge of something so prevelant can only be benificial.

You may prefer any that you wish. The fact of the matter, however, is that both make equally valid statements about the instant the universe began. The begginning of the universe (the exact instant of it) is what is known as a singularity in science. This is just a dressed up way of saying "we can never know." So science can extrapolate back to the very instant before the big bang, but the actuall hypothesized big bang is beyond the relm of science. Of course, this doesn't really matter, but i just wanted to point out that if you wan't to be a responsible scientist you can make no claims about the instant of the begging of the universe. Of course if you want to be a philosopher-scientist (who doesn't man?) then you can say whatever you wish, just don't expect scientific data to back you up. Cool

Well, as far as we know the electrons do not collide much, but then again the electrons are not orbiting the nulceous either, so that is not a valid comparison. That is not what was suggested at all. What swansont ment was this; Objects in orbit that collide with eachother will most likely knock eachother out of orbit. Thus, over time, such objects will be eliminated. That is to say that orbits that interfere with eachother are mutually unstable. Of course this does not quite really explain why all the orbits that would be left over by such a process of elimination would nessesarily be in the same plane. Cool

fafalone, you are ignoring one important detail, people are going to school to study how something works. In particulare, they are going to school in order to study how things in their major works. Thus, if someone is going to school to learn how to fly an airplane, they should be required to learn how to fly it. If someone is going to school for electronics, then they should learn how a transitor works. If someone is going to school to learn to ba a mechnic, then they should learn how a car works. Similarely, if someone if going to school to learn science, then they should be required to understand how things in science work. As it happens, for most sciences, math in a intimate part. Thus, it is reasonable to require students in science to learn how math works. Furthermore, for any major that requires mathmatics, it seems reasonable that people would understand how the math works. Your above examples are flawed, becuase in then people are not trying to study the things you have listed. They are not attempting to become professionals in these feilds. So, there is no reason why someone who is not an electrical engineer should be able to understand how a transitor works. However, if someone is a electrical engineer, they had better know how they work. Similarely, if someone is studying something that makes extensive use of mathmatics, then they should be able to understand how the math works. A better analogy might be, you would expect an engineer to understand how the diagnostic tools that he uses work. It is just important to have a firm understanding how the conclusions in your field are reached. OTherwise, the conclusoins might appear as if they were reached by magic, which is hopefully not the case. i do not wish to appear mean, but i can't belive you actually belive this. How can you fully understand a solution unless you understand how it is derived? Thus, we see that it is the process by wich the answer is arrived at that is the most informative. The answer is just that, an answer. But the reasoning that we use to arrive at the answer tells us what the answer means and why we should care about it. Many schools do if fact offer several math cources. One for mathmatics and "hard" science majors and one for people that are not quite as interested in how the math works. Of course both of them still have quite a bit of theory to them. But if all you want is to learn how to type in numbers in a calculator or a computer why spend thousands of dollars a quarter for this? Buy a book. It is much cheaper. NO student is forced to learn anything. You choose what you wish to take from the coursre and what you do not. that is your choice. There is nothing wrong with zoning out on parts you are not interested in (i do it all teh time). However, just don't go whining when you get to a probelm later in life that you need that knowldege for (also happend to me) or don't complain if you don't get the grade you want. You have to decide if it is worth it to play the game in order to get the grade. I guess that all i am trying to say is this. You pay the school you attend to educate you as best they can. People who have spend many years in the real world have learned that it is best to understand theory, so they teach it. But in the end, it is your choice as to whether or not you are going to take advantage of the opertunity to learn. Just don't complain later on if you were offered the oppertunity to learn something, but didn't take it. Then it is your fault. But it is the schools obligation to learn you as best they can, and this includes theory.

i would agree with dave. It could probably be done -- at least we could turn them into the best approximation we have, a computer. However, where would this get us? I seems like a bad idea to build a computer where the fastest comunication bewteen to nodes (the two closetst stars) would be on the order of years! At least that is my thoughts, though i admit i am quite ignorant on this subject, and could easily be missing the whole point (or even be entirerly wrong)

sup gene! Well, perhaps i only seem really knowledgable. Its a funny thing, but the more you learn the more you realize that there is so much more to learn. But of course that is cool, as long as you enjoy learning Personally, i am 24, pretty young, really, as far as the scientific world goes. And really, this shows in my understanding of chemistry. While i do know a bit of general knowledge, i am completely ingnorant still when it comes to what i research, but then again, i still have 4 more years to learn it As far as how we know what we know. It is a combination of several factors. First, i have been in school for almost 20 years now, so you would expect i would konw something. Secondly, i have read some stuff, but then again, i have been alive for 24 years, so that is to be expected to. Thirdly (and prolly most important) i have not hesitated to ask questions. If i feel that someone might be able to answer a question that i have, i ask them, and i pay attention to their answer and try to understand what they are saying. Then i ask more questions, and so on and so on... Of course you must always question what you are told and you must trust those that give you answers, but after a while (24 years) of asking questions you will be just as knowledgable (prolly more, really) as i appear to be. In short, don't get discuraged or impressed by our knowledge. It is just a by product of our interets and the fact that we have been alive for a while If you keep up asking questions (like you are doing) and pay attention and keep a sense of wonder, you too will gain much knowledge. But enough of that, onto your question (that is the whole point then isn't it?) Well, i do not really profess to be a guy that knows alot about liquids, not do i study them extensively. As such i do not really know many of the techincal terms that are used to describe the strengths of adhesive vs cohesive forces. There are many things, however, that i know are talked about that are reflections of cohesive and adhesive forces. i will give a brief run down of them here. First off, as has already been mentioned, there is surface tension. This is a measurement of how much the liquid/gas interface does not wish to be distorted or how much this interface resists applied pressures. The phenomenon of surface tension is a result of the cohesive forces of the liquid and the almost non-existance cohesive forces with the surrounding gas. By measureing the amount of pressure required to break the surface of a liquid, we can measure its surface tension. It turns out that boiling point can also be used to say something about the cohesive forces within a liquid. Liquids evaporate when the individual molecules gain enough energy to escape the reast of the liquid. In another thread, it was mentioned that temperature is really just a measure of the average kenetic energy of the molecules in the thing whose temperature is being measured. Thus, when the temperature of a substance increases, the average energy of the molecules in that substance increases as well. Remembering that cohesive forces are the forces between molecules in a liquid, we see that in order to boil, the molecules in the liquid must gain enough energy to overcome theses cohesive forces. Thus, by measuring the temperature at wich a solution boils (and hence the energy of the molecules required to boil) we can learn sometihng about the strength of the cohesive forces within the liquid (the forces that must be overcome if the molecules are to trasition from liquid to gas). Another commonly used term is viscosity. Viscosity is a term that describes how well a liquid flows. Water is a liquid that flows quite well, these liquids are called "fluid". Molassas or maple syrup (or hoisin sauce) are examples of liquids that do not flow very well, these liquids are termed "viscous." It is not hard to imagine that a liquid in wich the forces between the atoms is strong and not very dynamic (cannot change very quicky) will be quite viscious, where as in a liquid that is fluid the attractive forces are either weak or highly dynamic. Thus, we can learn a bit about the cohesive forces from viscousity (though it is hard to tell the strength from this alone). As far as adhesive forces go, as mentioned before contact angle can be used to determine this. At least qualitatively. That is, if you make a small drop of a liquid on a surface and then measure the contact angle with this surface, it will tell you something about the relative strength of cohesive vs. adhesive forces. Anyways those are just a few terms that i can remember hearing that migh be able to be used to say something about cohesive vs adhesive forces. I am not quite sure how to make any quantitative statements, but these are at least some qualitative things that could be said/examined. To further understand what might cause adhesive and cohesive forces, you might want to look into the so called "inter-moleculare" forces. For starters, check out london forces, dipole-dipole interactions, and hydrogen bonding. I would talk about them right now, but i have been writting for a while, and now i have a book (The name of the rose by Umberto Ecco) calling. If you have trouble finding or understanding expliantions of these forces, then just ask and i will try to write up something on it. Perhaps i will even write it in word, so that you don't have to put up with all these mis-spelled words :/ Cool, well enjoy the learning! Lates.

yuppers, i am a chemist. Or rather, i am studying to be on, i suppose. What about you, what do you do to saty out of trouble?

yeah 5 to 1 ain't bad at all! cool sweet! i think that i will put liquid soap in one. Then in the showere I can just spray myself down with soap. LOL! awsome. also, i must now determine how to make silly string. I will have the worlds largest supply of silly string ever. muhahahahaha! nations will bow to my will in fear! anyways, cool deal YT, thanks for the info

I think skye hit it pretty much on the head. That is, chemical engineers take known processes and try to make them useful or more effecient. Chemists try to discover new ways of doing things and novel chemicals. Of course this is totally an arbitrary definition and rarely do you find it stricktly followed. That is, many chemists try to adapt known processes to do what they want them to or they are interested in making something practicle and many times chemical engineers have to do some fundamental research along the way in order to get things working well. But as a general rule of thumb the above definition will work. So in order to decide whether or not you want to be a chemical engineer or a chemist, you must decide what sounds most fun to you. Making up new stuff, or trying to make "old" stuff usefull. Of course you gotta look at the pay scales and schooling involved. Engineers have the advantage that they get paid alot for their bachelors degrees. But scientists have the advantage that they can do whatever they want. That is to say, no one else really determines their research direction. WHereas engineers usually belong to firms and are not allowed to do anyting that would not be profitable. But then again to be a chemist and do what you want, you must have a Ph.D. and then you are looking at 5-7 more years after college. Anyways, i guess you just kinda have to decide whether or not the freedom to chase whatever interests you is worth an additional 5-7 years. Or perhaps you really enjoy a difficult effeciency problem. Many people do.

can you buy a giant can on butane? and can you just get that can refliled when it runs out? What kind of place would sell/refill large butane cans? Sounds cool, perhaps i will have to try it

i would like to chime in, if i may... First off, another great question gene! It is awsome to see someone obseve the world around them and then become interested in it. I would say that you have curiosity to become a great scientist Now for the question... As far as water dropplets on glass go (or really droplets of any liquid on anything goes), there are really two things that you must consider. First there are the cohesive forces. These are the forces that people have been talking about so far. Cohesive forces are the forces that attract moelcules in a liquid to themselves (hence, if some one makes an argument that holds together, we say it is cohesive). Secondly, there are the adhesive forces. These are the forces that attract molecules in a liquid to a solid surface. (Hence, something like tape, that sticks to something else, is called an adhesive). Anyways, in order to understand why a drop of liquid, or a surfaceof a liquid, looks the way is does, we just need to consider these forces. First off, we should consider the boundry between liquid and gas. That is, where the liquid ends and the gas begins. The gas (think "air") is not really a solid (hence gas, duh). Thus, there is not anything stable for the liquid to interact with. Thus, we pretty much ignore any adhesive forces bewteen the molecules of the liquid and those of the air. Becuase of this, we find that there are only cohesive forces when we consider this boundry. That means that there are only forces holding the molecules of the liquid together, not pulling them appart. (or as swansont put it, there are only forces "inwards" and not "outwards"). These forces will pull inwards constantly. Thus, the boundry between gas and liquid will assume a shape so as to be minimal. This is why a drop of a liquid will become spherical (a sphere has the smallest surface area to volume ratio). Also, this is exactly why we observe the property of surface tension. The surface of a liquid will resist any change that tries to increase its surface area. Again, this is due to the presence of coehsive forces and the essentially absence of adhesive forces. Next, to consider is the boundry between a liquid and a solid. Here we can no longer ignore the adhesive forces (the attractive forces between the molecules in teh solid and the molecules in the liquid). Thus, we find that there are three possible states. The adhesive forces are either stronger than, equal to, or less than the cohesive forces. If the adhesive forces are greater than the cohesive forces, we will find that a droplet of liquid will be flattened against the solid surface, as the molecule will try to maximize this interface. This is becuase there is now a dominate "outward" force). If the adhesive force is less than the cohesive force, then the liquid will form a "bead" like shape on the solid. (think water on wax). This is becuase there is still a dominate "inward" force, so that the liquid will attempt to form a sphere. It is of course prevented form forming a perfect sphere, however, by the presense of some cohesive, or, "outward" forces. If the adhesive and cohesive forces are balanced, we will find that the liquid dropplet will form the intermediate between a sphere and a flat shape. Wich makes sense. Now, it just so happens that for water on glass the adhesive forces are greater than the cohesive forces. So, for an unaltered glass surface, water on it will look "flattened". That is to say water dorplets on glass will not really bulge out. (you can see this for yourself if you look at water on a glass stove, or if you look at the windows of your house when it rains). Also, another cool effect of this is the "minescus" that we observe when water is in a glass tube, such as a graduated cylinder. That is to say, since the the adhesive forces to glass are stronger than the cohesive forces, the water will tend to "crawl" up the sides of the cylinder. Becuase of this, we will observe that the liquid surface looks carved out or bowl-like (if you have seen this, you know what i am talking about). Of course, no all liquids must have this minescus. Liquids that have a higher cohesive force than adhesive force to glass (such as mercury) will have an "inverted" miniscus. That is to say the liquid's surface will be domed out, or will form a bulge. Well i hope that helps out some. This is just a cursory introduction to cohesive/adhesive forces. There are many many types of these forces, all of which have their varying causes and it is a cool thing to think about. But for the purposes of this post and your question, i think this is prolly good enough. If you want more information, just ask!

Here is where you go wrong. There are radioactive elements within the earth. Actually, this was quite the mystery for some time. Not till just a while ago (sometime in this century) could people expalin why the earth was as warm as it was -- at least and be as old as it should be. Until people really understood that nulcear reactions occur, no one could understand how the earth could be billions of years old, yet not be a cold frozen rock. If there was no heat sorce, then earth should have long ago lost its heat to space. However, it turns out that there are enough radioactive materials in the earth, that they have helped out keeping the earth warm all this time. So, we see that the earth can be really really rediculously old and still be a nice temerate temerature. At least i think i remember readgin this somewheres

has anyone here seen "cube"? that is a crazy movie too. Quite good. as far as matrix goes, i thought it was pretty good, but it seems to rehash ideas that everyone has had as a kid (ie. am i dreaming now? how do i tell that i am really awake? ect.) it seems to me that the point that should have been made (and was made once durring the second movie) was that people are dependend on machines. Even if the machines are not directly enslaving them, people, out of nessesity, has enslaved themselves to machines. A good book that makes exactly this point is Kurt Vonegut's player piano which i enjoyed thoroughly

People said that about going to the moon too. Perhaps one day we will find ourselves on venus as well. (Though i must admit right now it does seem a rather bad idea)

actually, the tidal forces the moon exerts on the earth are stronger than the ones the sun exerts on the earth. So first, the erath will stop spinning with respect to the sun (ie. same side of eart will always face the sun. Then, eventually, both the moon and the earth will be titally locked to the sun, with the earth and moon always in the same position to the sun (and at the same time in the same position to themselves). But that will take awhile to happen, so don't worry about buying up all the good real estate yet

ah, addition, my old nemisis -- we meet again. Perhaps you have been vicotrious this time, but next time, i shall add you correctly!!!!! muhahahahaha!!!!!!!!!! cool, thanks wolfson

hmm...it appears to be as wolfson says. There doesn't really seem to be a question. What forum are you from, if you give us a link to the original post, perhaps that would shed some light on it?

My whole point is that i am not convinced that this is nessesarily always the case. Can you provide some proof of this? That is proof that the delta H for a reaction between different chemicals cannot be zero?

Of course if you are talking about an activated process then you are talking kenetics, not thermodynamics and this really has no bearing on the discussion. The discussion has been revolving around two point (actually the same point, but written differently). The first poiint (a question) is as follows... THis is a question that is clearly a thermodynamic question. It is concerned with the left and right side of the chemical equation. The products and reactants. Not how you got form one to the other. Again, he is asking about edothermic vs. exothermic. As i tried to point out in my above post, /_\ H (cool way to write it, man) is a state variable and does not depend on path. Thus, any argument that deals with mechanisms (that is anything that tries to address activated process, activation energy, ect.) is not addressing the main question; can there be a reaction that has a /_\ H of zero? Now, of course i can write a reaction that will have a delta H of zero. That is really not a problem. I have already written two. I think the more interesting question, which comes out of the above on is as follows... (edited slightly) Now, this is clearly a question of bond energies of the two chemicals. That is, can two different chemicals have the same exact potential energy (wich is stored as heat energy, enthalpy)? Now again, we are talking about the realative /_\ H between these chemicals. There is no need to talk about ketetics of an enterchange between the two. Thus, activation process and activation energies are right out again. So we see that what you said in quotes above does not apply to this question. This comes close to addressing the question. I say close, becuase it does not really. What you have done is cleverly hide a discussion of activation energy. You have done this by splitting a reaction into two parts. A reaction where A disociates into X and Y and a second reaction where X and Y combine to form B. However, do to thermodynamic considerations, we can just write this as the net equation A --> B. Then look at the total change for A to B. The original stipulation was that a reaction can occur in wich the bond energies on both sides are equal (see above quote of original question). Thus, i said that there could be a reaction A goes to B, in which the bond energies of A and B were the same. By breaking down the reaction into composite parts, you are looking at A goes to X and Y. THere are no constriants on X and Y, so it is true that they could be of different energy. However, this is inconsiquential. I am not concerned with X or Y. Rather A and B. I can ignore any trasient species that i wish to. Again, this is a direct result that /_\ H is a state variable. Thus, while this does apear (at least at first) to adress the question. It really does not. Again, it breaks down to an analysis of reaction rates -- kenetics. But we are talking about thermodynamics. I must stress again that the question is; can it be proved that two different chemicals must have different energies? THis is not so much an argument as it is a definition then. These are a series of definitions and are not really arguments. But thanks for taking the time to make sure everyone understand the definitions. well, um, yeah. That is kinda the definition then isn't it? Endergonic means a positive change in free energy, exergonic means a negative change in gibss free energy. So, of course enedergonic and exergonic reactions are accompanied by change in energy. That is the definition. First off, this really doesn't make sense. BY DEFINITION, exergonic and endergonic reactions are accompanied by a change in energy. The must be. Secondly, you have not shown that all reactions are accompanied by a change in energy. What you have done is shown that there is an activation energy that must be crossed. And i am assuming that you mean to claim that this is the energy change the must accompany a chemical reaction. However, this is not quite true. There is no theorectical lower limit to the activation energy of a complex. Thus, it is quite easy to imagine a complex (or several complexes) for wich the activation energy between them is zero. We can further stipulate that some of these complexes are at at the same energy. Now between these complexes we have a reaction that has a /_\H of zero and does not have any activation energy. Thus there is no energy accosiated with the trasition. Now it may seem a bit like cheating to just make up these complexes that have no activation energy. However, it really is not. They are just theoretical complexes, and we are considering theory here aren't we? What they really allow me to do is to show that any sort of kenetic argument truly does not apply at all to the original question. And so we find that we can ignore activation energies (like i have been saying all along) and move on to the real question. That question has been, and remains; can you prove that two different chemicals must have different energies? Now remember this is a thermodynamic question. Please try to refrain from any discussion of the path taken between these two chemicals, as such a path is nessesarily meaningless for the purposes of this discussion. cool