rich

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Everything posted by rich

  1. Have you considered sending your daughter to a Magnet school? I have done very little research on this type of institution, but from what I've heard, Magnet schools are 1) public [which, I infer, means you'll pay nothing in addition to the tax dollars you already pay] and 2) specialized [they are based heavily on math/science/engineering, or fine arts, etc. and accept only the most accomplished]. I once knew a guy who was an excellent math teacher, but was not the type of person who could control a typcially rowdy class of high schoolers one often encounters in public schools. He opted to teach at a Magnet school so that his efforts would not be wasted on academic slackers. I don't know how old your daughter is, but this could be a solution for her sometime in her life.
  2. I just graduated with my M.S. degree in physics, and I'm currently interviewing for jobs with companies. Here is my problem: On every interview I've been on so far, someone (usually a Human Resources person, but also other scientists) asks me what I do in my spare time, what my extra-curricular activities are, what my non-scientific hobbies are, etc. Often, they ask more questions about my personal life than my academic/career qualifications. I have no idea why they would be interested in such insignificant details about my personal life; I would like to think that they're interested in what I'll be doing on company time, not my own time. Friends of mine have told me that many companies are impressed if applicants are involved with charity work, for example, volunteering with Habitat for Humanity. Others have told me that companies are impressed not just by an applicants' volunteer work, but by their general social activities; if an applicant has organized a weekend tennis club, for example, companies are more likely to hire this applicant. Being a very busy person, and also having logged zero hours of formal volunteer work in my life (and no desire to begin doing so), I tell my interviewer the truth: aside from working out, and the occasional night out with my friends/girlfriend, I spend what little free time I have reading, or working on other science-related projects. And, based on my interviewer's body language/tone, I usually infer that they are disappointed about something I have said. So my question: Would it be moral to lie when asked what I do in my spare time? I don't want to be penalized because I don't volunteer at the local hospital, or because I don't enjoy rock climbing on the weekends. But, the purpose of my lying would be to gain a value (the job) -- so is lying definitely wrong in this case? Would my lying be a form of force, if I am hired under false pretenses? I know this post is long and meandering, but I've done my best to condense it.
  3. Thanks for the link, I'll check it out soon. I had been taught years ago (in high school, I think) that water is polar because oxygen has a greater affinity for electrons than does hydrogen. But, this would not explain how why H2O is nonlinear.
  4. I've read two accounts as to why clouds become attracted to the earth's surface, which is of course a precursor to lightning. One hypothesis is that a cloud's water molecules, being polarized (oxygen atom carrying an effective negative charge and the two hydrogen atoms carrying an equal effective positive charge), all align inside the cloud with their oxygen atoms pointed toward the earth and the hydrogen atoms pointing away from the earth. This creates a large polarization of the cloud, that in turn polarizes the surface of the earth. Another hypothesis is that as clouds move through the air, the friction between cloud and air knocks electrons off of the cloud, giving the cloud a net positive charge, creating a polarization on the earth's surface. The first hypothesis assumes that clouds are not charged, but polarized; the second assumes they are indeed charged, and does not discount the possibility of polarization being present also. One of these hypotheses has to be wrong. Anyone know which one?
  5. Polar, polarized -- call it what you will, the point is that the oxygen and hydrogen atoms that make up water do not share their valence electrons equally. Oxygen keeps the valence electrons for a greater share of time than the hydrogen atoms do, and so the molecule as a whole has a slightly positive end, and a slightly negative end. I'm sure we both agree on this. And I've imagined clouds having this same feature -- a slightly positive end, and a slightly negative end, but neutral as a whole. I don't know how this would arise in the first place, as I've stated. But assuming it does occur, then I was thinking that if two clouds meet with their oppositely charged ends facing one another, then the attraction would be great enough to rip off some electrons, resulting in an electric current. But now, I realize, this is probably not physically reasonable, because as you said, polarization does not lead to a charge imbalance. So I'm still not sure what's going on with the clouds.
  6. Maybe I wasn't clear enough. The water molecules themselves are already polarized; water molecules are polarized naturally, and each water molecule can be thought of as a tiny dipole. What I meant was, the water molecules as a group may be ordered in such a way as to polarize the cloud. In other words, somehow all the H2O molecules at the bottom of the cloud might have their O atoms pointed toward the earth, and their H atoms pointed away from the earth. I don't know how this might occur in the first place. There is, of course, the earth's natural magnetic field, but its strength is only of the order of 1 gauss, so I doubt it would effect the water molecules significantly. Polarization, though, would account for lightning's jumping from one cloud to another, I think. If the positively polarized part of one cloud drifts near the negatively polarized part of another cloud, a strong electric field will arise -- eventually resulting in dielectric breakdown of the air in between the clouds, i.e., lightning.
  7. Lying on Job Interviews

    As I've said in my latest post in this thread, I've decided that it is not moral to lie in a job interview. But, I never gave my reasoning, so I'll do so now. Hopefully, listing my thought process gives everyone a new perspective on this topic. First, some preliminaries: Lying/deception/fraud are forms of force. If I am hired under false pretenses, then I am effectively taking my employer's money without his permission. Which is force -- almost by definition. Now, since lying is a form of force, I may use it only in retaliation against a party that initiates the use of force against me. That is, a party that seeks to harm my values. And if I'm on an interview, then obviously no value of mine has been threatened by the employer; how can he take my job from me, when it isn't even my job yet? So I have no justification for initiating the use of force. Lying would make me an initiator of force. Hence it is immoral to lie on job interviews. This reasoning is nice and tidy, but solid, I believe.
  8. Lying on Job Interviews

    No set-in-stone occupation yet, I would simply like to work in a technical position (e.g. engineer, physicist, etc.) for a company. Teaching is not for me, and working at a government job is a last resort. Industry is where I want to be. I've had 4 interviews with 2 companies so far, and each time, questions arose regarding what I do in my free time. In all honesty, I don't think I'll be expected to volunteer at the jobs I apply for. Nor do I think my private life will be meddled into once I have a job. What worries me, is that many hiring managers do their hiring based on non-work related criteria. Some examples: An engineer I know landed her co-op because she played on her university's softball team. Another friend of mine, with a business background, said his interviewer was impressed that he had worked as a camp counselor years earlier. And one woman, fresh out of college with her Economics degree, said all she talked about on her job interview was weddings! (she got the job) If what I mentioned above are the standards employers go by, then I definitely cannot "compete" for a job. This is why I was tempted to lie.
  9. Lying on Job Interviews

    I've done a lot of thinking about this matter today, and I've decided that I can't justify lying. A company has the right to set any hiring criteria it wishes, however irrational or silly. But it is horribly frustrating to be turned down for a job I know I am qualified for, because of reasons completely unrelated to the job. In the future it will be extremely difficult for me to tell an employer, in the most polite way possible, to keep out of my private life. I have no desire to be a martyr; and, for awhile, I thought that I'd rather be a liar than a martyr. The temptation to lie is very real. As for the myth that socialites, or people with diverse interests, make better employees than loners: I think the notion is ridiculous. Did the Chicago Bulls draft Michael Jordan because he volunteered at Red Cross? If you're deciding among 5 neighborhood boys to hire to mow your lawn, do you pick the one who has an interest in opera?
  10. I've read the threads you directed me to, and you have said that nobody can state the "real" difference between mass and energy. Would it be better to say, not that energy has mass, but that energy has inertia? What I mean is, energy (a light beam, for example) is gravitationally attracted to mass -- but this is by no means saying that energy is a form of mass? Perhaps it'd be better to say, energy and mass both have inertia -- but mass is mass and energy is energy, and mass is not energy and energy is not mass? I'm thinking of an analogy. Consider the relationship between temperature and average kinetic energy of a classical ideal gas: (1/2)*m*v^2 = (3/2)*k*T, where k is Boltzmann's constant. This relationship does not say that temperature is a form of kinetic energy, nor that the temperature is merely the kinetic energy, multiplied by a few constants. It is simply an equality that holds for classical ideal gases. In other words, it is not a definition. The definition of temperature, is [the partial derivative of entropy with respect to energy], inverted. Should we think of E = m*c^2 the same way? Not as a definition, but merely an equality that holds for massive particles?
  11. What about the phrase, "conversion of mass into energy"? This phrase is commonly printed, in places from newspaper articles to textbooks. But A is A, and mass is mass, so how can mass become energy? Mass and energy don't even have the same units!
  12. Einstein and Kant

    While we're on the subject of Einstein's social beliefs, I have wondered for a long time: could Einstein possibly have been Rand's motivation for the character Dr. Robert Stadler in Atlas Shrugged? In Atlas, Stadler is said to be the only one who truly betrayed the public, because Stadler "had a mind to know better" than to promote socialistic ideals, as Einstein did. In an essay from The Voice of Reason, Rand says something about having intended Stadler to illustrate the importance of philosophy to scientists in general. But, since Stadler was as big a celebrity scientist as Einstein was, and also as brilliant, I've always thought that Stadler was Rand's depiction of Einstein.
  13. My girlfriend is in her second year of medical school, and the material she is currently studying involves electrocardiograms. Her class is given printed notes on ECG, and the notes give a basic introduction to electric dipoles. Here is how the notes define an electric dipole (almost verbatim): "An electric dipole consists of two equal, but oppositely charged, point charges or "poles" separated by a distance d. Since a battery features two equal, oppositely-charged poles, a battery is an example of a dipole." I was very surprised to read this. Being careful not to sound too pedantic, I told my girlfriend that most physicists would definitely not agree that a battery can be thought of as a dipole. For one, the separation distance of the battery's poles is not small with respect to the distance to your typical origin of coordinates. If a person's eye is taken as the origin, the person can almost always distinguish the two poles; resolution of the two poles is nearly perfect. Also, the charges of a dipole are typically so close together that nothing material exists in the space between the charges. The poles of a battery are separated by battery fluid, etc., and so the field of a battery does not resemble that of a physical dipole. Of course, there is technically no such thing as a pure dipole, because a pure dipole represents two charges being separated by no distance at all. All real dipoles are physical, that is, separated by a "finite" distance. But what is meant by "finite"? Is there a rigorous definition of a physical dipole other than that the charges are separated by a "small" distance? I doubt the true definition of a dipole makes much difference to a doctor's performance anyhow, and I know my girlfriend certainly has more important things to worry about in her studies. But as a physics student, I am curious to know when the concept of a physical dipole breaks down.
  14. Math and Physics Books

    Would someone studying under this kind of curriculum, from the perspective of the TEW, even know what a "wave" is at first? I mean, would he have an everyday example of a wave (such as an electromagnetic wave) to keep in mind as a visualization? Also: when would this person eventually begin studying the "mundane" topics the Feynman Lectures were designed to circumvent, such as balls rolling down inclined planes or boundary value problems in electrostatics? Toward the end of their undergrad career, or would they even have to wait until they got into graduate school? I imagine learning the TEW would take quite a bit of time, and I know that learning relativistic quantum mechanics certainly is no walk in the park. Could your approach be extended to a mathematics curriculum? I have never taken a course in abstract algebra, but someone told me that it is even more fundamental than the algebra that is learned in junior/senior high school. Would students learn abstract algebra, with all its complicated theorems and proofs, before they learned basic, everyday algebra? Would they study general tensors before they studied vectors and scalars?
  15. Electric Dipoles

    Thank you for the very informative response, ewv. I have a lot to think about now. I have never heard of the term "dipole distribution", but I will read up on it. Any two opposite charges in any configuration? Is a charged capacitor then technically a dipole?
  16. Math and Physics Books

    Not to get too far off subject of textbooks for realitycheck44, but I have never been a fan of physics authors' presenting the math needed for a topic along with the topic itself. I have always preferred to concentrate on the physics exclusively, and learning new mathematics at the same time has always given me, and many of my fellow students, a lot of frustration. (This is why I recommend R. Shankar's book for learning quantum mechanics: all the math needed for the whole book is presented in the first chapter, allowing the student to learn the math first, and then be free to focus solely on the physics.) Also, in regards to the Feynman Lectures: Feynman himself, in one of the books' prefaces, says that a central aim of the Lectures is to provide a more "interesting" approach to learning physics, by introducing students to relatively recent topics(such as relativity and quantum theory) early on. But, doesn't this approach go against the "hierarchy" principle that is emphasized by Objectivist teachers? Particle kinematics, electrostatics, and finding moments of inertia may not be as "exciting" as relativity or quantum theory, but they are fundamental topics. Shouldn't they be taught first, not because they came first historically, but for hierarchy's sake, in other words, teaching "from the ground up"?
  17. Math and Physics Books

    realitycheck44, If the University Physics book you're referring to is by Roland Reese, then I personally would not recommend it, because I myself found it hard to follow as a college freshman. For a general introductory physics book, I would recommend Physics for Scientists and Engineers by Douglas Giancoli. Although some have found this book to be too elementary and not challenging enough, I really wish that that book would have been used in my freshman physics courses. Are you majoring in physics? If so, I have an extensive list of physics authors that I would recommend; and also, I'm sorry to say, an equally long list of authors I would avoid. Oh, and Stewart's book Calculus is a great college calc text.
  18. A very stimulating earlier post in this group from a few months ago ("Einstein vs. Newton") taught that space is not a "container" in which objects exist, but a relation between objects. Thus, if all the matter in the universe were to disappear, space would also cease to exist. I accept this argument. But, is this also true for fields? For instance, if only a single electron exists in the universe, and absolutely no other matter, would that electron still project an electric field? Does a field require something to act on in order to exist?
  19. question about fields

    Sorry I've been away for a few days, I've been having computer problems. I understand what you mean, Stephen, when you say that a field cannot be defined in terms of force, because "force per unit charge" carries some ambiguity due to the discrete nature of charge. So I will have to define "field" in a way that does not involve forces. And I'm having trouble doing this! Are you referring to the Dirac delta function(al)? As to Jackson's textbook: my university is one of the only universities in the country to NOT use Jackson. Much to my dismay, my graduate E&M class used Landau and Lifshitz' book The Classical Theory of Fields.
  20. question about fields

    By "field" I mean whatever mechanism by which an object exerts a force on another object. For simplicity, I'll choose the electric field E of electromagnetic theory. Anything you can tell me about the existence (or lack thereof) of this field, I'd appreciate. Thanks, and I apologize for not having read the previous threads in this Forum that deal with the structure of the universe, etc.
  21. question about fields

    Well, after glancing through Little's paper (and being completely bewildered for the most part!), it seems I am in no position to debate the physical/metaphysical/ontological status of fields. I am by no means an expert on field theories; I am a 2nd year master's student in physics, and my research is in no way related to field theory. So I'll have to do a lot of independent study before I can begin to examine the nature of a field. To clarify my original question in this topic, I'll describe a thought I had recently. From the "Newton vs. Einstein" topic in this forum, I learned that space is defined to be a relationship between objects, and has absolutely no existence in and of itself; the old Newtonian notion that space is a "container" of matter is wrong, and Einstein's notion of space being only a relationship amongst objects is correct. Okay. But....that would mean that there exists absolutely nothing beyond the edges of physical universe; in other words, the matter that resides farthest from us defines the edge of space: there is nothing "beyond" that, not even space. So...say an electron resides at that edge. Of course this electron is surrounded by its own electric field (however one defines such a field), as are all electrons. But since the electron resides at the edge of space, can its field extend out in ALL directions, including the region of "no space"? Or will it only extend inward, toward other objects, and not outward, where there are no other objects and therefore no space? Hence my original question: does a field require space to exist? I hope this clarifies my original question! Thanks guys!
  22. How your computer works

    Is this true? I thought, the less accurately you know their position, the less accurately you know how <i>fast</i> they're going. <i>Direction</i> of motion carries no uncertainty. In other words, it's the length of the momentum vector, not the orientation, that in uncertain. Am I right?
  23. question about fields

    That is exactly what I'm asking. As a side note, I realize that the concept of a field is a bit wishy-washy, or "nebulous" as Stephen describes. Perhaps we need some new terminology? Maybe instead of saying "field" we would do better to say "spread" or some other word describing what we envision to occur in nature. And I will definitely check out Little's paper, thanks for the link to that.
  24. viscosity question

    Thank you, EWV, for your informative response! I will look into the fluid textbooks you recommended, and I will also check out books on kinetic theory. But thanks again for taking the time to share your (vast) knowledge of the subject I find it interesting that nobody has worked out a rigorous, encompassing theory of viscosity as a function of temperature. Exotic theories exist for everything from quarks to supernovae, and yet something as everyday as "viscosity of a fluid as a function of temperature" somehow managed to slip through the cracks. Anyhow, I have a lot to think about now. Hopefully I make at least some progress.
  25. Can anyone explain why the viscosity of a liquid decreases with temperature for a liquid, but increases with temperature for a gas? I've been reading Frederick Reif's (excellent) book Fundamentals of Statistical and Thermal Physics, and Reif gives arguments that involve mean free path, mean time between molecular collisions, etc., but I am still not convinced. Not that I don't believe Reif; I just can't seem to understand this (in my opinion) non-intuitive phenomenon. My reason for asking is pure curiosity. And because there's a chance I'll actually need this one day as a physicist.