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Physics Classes Should be Experimentally-Based

  1. Physics is strictly a theoretical subject only

    2 vote(s)
  2. Physics is strictly an experimental subject only

    0 vote(s)
  3. Physics is both experimental and theoretical, with experiments proving the theories

    33 vote(s)
  4. Physics is both experimental and theoretical, with no experiments needed to prove the theories

    0 vote(s)
  1. Jun 9, 2007 #1
    Many high school and college students do not understand Mathematics and/or Physics. Based on the schools I have attended, I have observed that Physics is taught from a textbook perspective, with a lab class full of nifty experiments that do not conclusively prove anything. I beleive we have taught students to become arm-chair Physicists. Physics is based totally on physical proof; Galileo figured this out because while everyone was arguing about whether or not heavy objects fall faster than lighter objects, he (according to legend) dropped two objects from the leaning tower of Pisa and found out the truth. Is it not amazing what we learn when we stop arguing and start experimenting! People can't argue with the facts! And the facts lead to a more educated people and a better world and economy! Why was it that technology didn't advance back in ancient times? It was because people allowed their mystical religions and preconceptions to control them, instead of the physical evidence. Now, I beleive we should take students into the lab before we take them into the classroom. Make them observe falling objects, collect the data, and come up with the equations. Once you have the data on paper, writing the equations becomes easy. I beleive that teaching students in this way would give them much more confidence in their problem-solving abilities. The goal of teaching (I beleive) is not to spoon-feed people facts that they must memorize, but to teach them how to get to those facts themselves; in other words, a good teacher will teach his students how to learn, not just what to learn. Please chime in and tell me what you think.
  2. jcsd
  3. Jun 9, 2007 #2


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    Not just physics, all sciences. That's the thing some people forget. Its doesn't matter how mathematically beautiful your theory is, it needs to apply to the real world for it to be science.

    I don't really think people have a lack of appreciation for physics experiments these day, I think there are less experiments in classes these days for two reasons:

    1)Money- people don't want to put money into buying good equipment.

    2)Liability- WHAT!!!!! Mercury Thermometers!!!!! Think of the children:surprised:!!!

    People are too afraid of being sued anymore. Hence, they don't let kids touch those horribly dangerous micrometers that they don't want to buy anyway. It's all screwed up.
  4. Jun 9, 2007 #3
    I think the answer to the poll question is "Physics is both experimental and theoretical, with experiments testing the theories". A theory is a mathematical idea that produces a prediction. Good theories have fewer free parameters, and thus produce highly specific predictions. In principle, an experiment can prove that such a theory is incorrect, but it can't conclusively "prove" [that] a theory [is correct]. (In fact it's slightly worse, due to experimental uncertainties.)

    I agree that it should be taught with a greater experimental basis. In first year, I though there was never a lecture that couldn't have been accompanied by an interesting demonstration (whereas in practice only a fraction were); I think this would be the best approach, making the lectures more engaging and constantly associating the abstract theory with experimental motivation. I don't think it would be practical to change the teaching format (delaying the theory) too much though, partly because we want to bring people up to speed on modern physics quickly so they can contribute to new advances.

    You didn't need to go so far as to blame religion for the time taken to develop modern technology. Aside from the alienation, it's not obviously a strong argument (e.g., important advances made by monks). And it was nothing less than experimental evidence that led people to think heavy objects (like stones) fall faster than light ones (like blossom petals); it is really by redefining their notion of "fall" (to separate out effects of air resistance) that you can say they were wrong.
    Last edited: Jun 9, 2007
  5. Jun 9, 2007 #4
    Good Points G01, I didn't think of these.

    Another concern of mine is how high-tech some college lab class tools can get. In one of my college physics labs, we were "demonstrating" Kirchoff's laws with a multimeter. The lab teacher never bothered to explain how the multimeters worked, and that they relied on the torque that is produced by the magnetic field that is created around a coil of wire (we were using analog multimeters). I was always the curious student, so I did my "homework" on these multimeters to find out how they worked, but almost no-one else cared. Basically, what the lab teacher was doing was saying "hey, students, here's a little magic box that tells you how much current is flowing through this wire, now use it to proove Kirchoff's laws"

    Rule number one: A PHYSICIST NEVER USES EQUIPMENT WHEN HE DOES NOT KNOW EXACTLY HOW IT WORKS. Physicists are not technicians, they are physicists. If the physicist does not know how his tools work, then he cannot know how to interpret the results of his experiments because he cannot know what effect his tools will have on the experiment.
  6. Jun 9, 2007 #5
    Good points, cesiumfrog. I realize that it was incorrect for me to say that experimental evidence can conclusively proove a theory to be true. I do agree that experiments can either proove theories to be incorrect or further reinforce their validity, but can never proove them to be true.

    Also, of interest to me are these monks you mention. Who were they and what did they discover? I'm not being sarcastic; maybe I could learn something here.
  7. Jun 9, 2007 #6


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    Dearly Missed

    I agree fully with this. It holds, of course, also with respect to early math education.
    that is why calculators should be banned in schools.
  8. Jun 9, 2007 #7
    Amen to that, arildno. I think kids learn how to press buttons on calculators but do not really understand the mathematical operations they are performing.

    I'll admit that when I was in elementary school, even though I was very good at understanding mathematical and science concepts, I was still just a kid and I learned to do some things that I did not fully understand. Let's face it, even some of the most analytical kids are no match for the "spoon feeding of facts without prooving them" philosophy that many schools take. In fact, I believe some of the elementary and middle school teachers don't really even know their stuff, and that's why they can't answer kid's questions. What's sad is that some kids (just being typical kids like I was) don't even ask questions and just believe whatever it is that they are being taught. That's not real education, that's just playing the copy-cat game.

    Now that I'm older and going into my fourth year as an engineering major in college, I don't play games with my education anymore.
  9. Jun 9, 2007 #8
    (Dr.P, the example I had in mind was Mandel "the father of genetics", but my point was just not to raise controversial issues where they are unnecessary or irrelevant.)

    I'm not sure about the calculators, computers and so forth. Sure, it's beneficial to society if "high-school drop-outs" know how to add, etc, but it isn't very often that someone needs to know a specific mathematical algorithm such as "long division". Would it matter if we taught students to use computer algebra software, instead of making them study various "tricks" for integrating particular equations by hand? What is the benefit in teaching row-reduction algorithms for inverting matrices, when efficient implementations of better algorithms are already widely available? Is it enough to understand what the calculator does, rather than how it does it? In practice experimental physics frequently depends on computers, whilst there is possibly no single person who completely understands how every element (of every level) of a typical modern computer actually works.
    Last edited: Jun 9, 2007
  10. Jun 9, 2007 #9
    I have no problem using an electronic calculator because I can perform the calculations by hand and know that the calculator is telling me the truth. However, when we are performing scientific experiments, we must know how the tools that are involved in the experiment are working. If I use a digital flow meter in some kind of a fluid mechanics experiment, I need to know exactly how that meter's accuracy is affected by temperature if I am measuring fluid flow at high temperatures.

    My point is that students must establish basic principles by using methods they understand. If you don't know how a multimeter works, then all you've proven is that the needle on the multimeter swings to a different position, you have not proven anything about electrical currents. You must first understand that the meter needle deflects because of a torque that is produced by the magnetic field that is created by current flowing through a coil of wire that is surrounded by permanent magnets. Also, because of the response time of the meter, it is possible to discharge a high-voltage capacitor and get a large surge current without the meter needle even deflecting by much. A student who doesn't know how the meter works might conclude that there was very little current at all, when in fact there was a very large surge current that lasted for a time period that was too short for the meter to measure. AS A PHYSICIST, YOU HAVE TO KNOW HOW YOUR TOOLS WORK.
  11. Jun 9, 2007 #10
    In my opinion, in a good physics class the day should begin after you give them a little background info and then have a lab, then you tel them to analyse the lab results and try to come up with their own explainations. Then give them lecture on important topics/concepts and then practice problems for the rest of the time.
  12. Jun 10, 2007 #11
    In my opinion people learn only when they do something by themselves. In that aspect, labs are usefull. Sadly to say, most classes are NOT usefull. I've taken a lot of classes yet most of the things I understand well came through reading books, self study and solving problems.

    So I would substitute the classes with programmed online classes where students have to answer questions and solve example problems while learning.
  13. Jun 10, 2007 #12


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    Are you kidding us?
    The best learning which I achieved was linked to laboratory sections for the courses. The lab exercises gave us instructional experiences that reading & lecture discussions alone could not achieve.
  14. Jun 11, 2007 #13
    I don't know.. I'm a high school physics student and I love the theory bit and I would prefer as few experimental works as possible, but I understand other people do like experiments and "get" the subject better with the practical works. I'm just more of a theorist type..
  15. Jun 11, 2007 #14

    Don't colleges teach string/MWI theory in college anymore?
  16. Jun 11, 2007 #15
    I empathise, Dr Proof. I want to know about the world, about space, time, and gravity, everything. Doesn’t everybody? No. My two teenage children don’t. They tell me physics at school is dull. I got the boy talking about it, and he told me that when he first did physics it was interesting, with Van Der Graaf generators and the like. But the teacher retired, and now it's most definitely dull, and all they do in the lab is "boring stuff like pendulums". Perhaps it's just my son's school, maybe it's the dead hand of Health&Safety, perhaps it's just an England thing. Maybe it's my fault. I’m not sure exactly what it is. But I see physics departments closing down here in the UK, and other science departments too, and I don't like it. I read about the number of A-level students taking physics falling 56% in 20 years, and it bothers me. And that's why I'm going to do what I can to counter it.
  17. Jun 11, 2007 #16
    Positronized: I understand where you are coming from, because I was once in high school and once had a view that is similar to yours. Theory is a very good thing because it causes people to predict physical things (according to their theories) and then prove those theories to be either correct or incorrect by scientific experiment. So, essentially, theories are good because they lead to experimentation.

    The Kelvin temperature scale is a good example of theory. The Kelvin temperature scale is based on the pressure of an ideal gas at different temperatures. Because this graph is linear, we can extrapolate the data down to 0 Pascals of pressure and find that the temperature at which gas molecules would theoretically stop moving is -273.15K, and we call this temperature absolute zero. It is important to note that absolute zero has never been experimentally observed, so as good as this extrapolation may look, we cannot trust it below the range of experimental temperatures. This does not mean that we dismiss the notion of absolute zero as being false, it just means that we must keep in mind that it is a theory that has not been fully-proven with experimental evidence. In fact, there are things in thermodynamics that suggest that we can come close to absolute zero but can never actually get there, so it is very important that we as scientists never assume our theories to be true.

    I say this respectfully, so please do not take offense Positronized: I think your logic behind loving theory and prefering as few experimental works as possible is actually flawed. If we have no experimental evidence, then we have nothing to think about. How would you know that all objects on the earth's surface, regardless of weight, fall with the same acceleration? The only way you know is by experimental evidence, you cannot make scientific conclusions based on anything other than experimental evidence. Theory and logical reasoning is a good thing, because it is another tool in the scientist's tool box that he can use to attempt to make predictions, but the scientist can never replace experimental evidence with theory. Without experimental evidence, the theories themselves cannot be accepted as truth.

    Physics is not a spectator sport! Physicists do not sit around in easy chairs coming up with theories and then writing those theories down as truth. Experimental evidence is the final judge.

    Here's an example. Let's say I told you that objects accelerate upwards when they are thrown away from the earth towards the sky. Would you disagree with me? If we were merely sitting around discussing the issue and had no scientific evidence you would have no reason to disagree with my theory that objects accelerate away from the earth when thrown towards the sky You would probably prove me wrong by finding some nearby object and throwing it upwards. The object would reach a maximum height and then fall back towards the earth, and thus by experimental evidence, and only by experimental evidence you would have proven my theory (that objects always fall towards the sky) to be incorrect. You could not have fought my theory with another theory, you had to use experimental evidence to prove my theory wrong Now, Positronized, do you see how dangerous it is to accept theories without requiring them to match up with experimental evidence? Galileo was thrown in prison because his experimental evidence did not match the Pope's theories. Galileo was an experimental Physicist, and the Pope was an armchair "Physicist".
  18. Jun 11, 2007 #17


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    Sigh........That's what I believe the problem with string theory is. There are no experiments. There is no way to test the theory. And until that happens, string theory really isn't physics in my view.

    Experiments are what actually tell us whether the theories we create actually describe the real world. People can say, "Oh but I find theory to be SO MUCH MORE INTERESTING..." Doesn't matter. Science is a mixture of both Theory and Experiment and both should be taught. One without the other is meaningless. Without theory, experiments are meaningless. Without experiments theories are meaningless and describe nothing.
    Last edited: Jun 11, 2007
  19. Jun 11, 2007 #18
    I think it is wrong to treat doubters of string theory like they are ignorant unenlightened ones. All we want is proof. There is probably no difference between a string-theorist and a mathematician, both don't care whether their ideas have any real-world application. The irony in the string theorist's cause is that they want some kind of a "theory of everything" that describes the physical world, yet they don't consult the physical world for evidence.
  20. Jun 11, 2007 #19


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    That should be someone's signature!
  21. Jun 11, 2007 #20
    I think that stringers may think that 'math' is the lab/experimental part of their theory.

    String/MWI, to me, is a philosophy/math theory/subset IN/OF physics. So many people jump on posters to 'CITE YOUR SOURCE', yet for some reason string theorists sources are other just other earlier math papers dealing with math theory.

    I seen so many posters criticized for their questions belonging (in the critics mind) to philosophy (and don't answer the question or offer any help), instead of physics, for a word out of place (usually 'why..?'), when every initial question in the 'physics' world IS/(can be considered) a philosophical question---then leads often to scientific inquiry. Other critical replies often make assumptions about answers from others and openly call the poster ignorant or his response a sign of ignorance. --Again not very 'helpful' on or from the critic of the post, or scientifically minded to find the 'source' of the errant question. A fifth grader can come in, even on the most respected posters posts, and call him 'ignorant' or 'having ignorance' for misspelling a word if that was their goal--(I think most of us are understanding of the nature of some posts and posters, and tolerate/overlook the nature of questions, spelling errors, etc. and look to the 'meat' of the question.

    This all leads to the question:

    Why do 'physicists' (theoretical and applied) tolerate string theory, when in every other 'area' of physics some 'source' of data is DEMANDED as evidence to even discuss a theory and not call it outright 'crackpottery' after all this time with no evidence? (what is it?--a dead horse?, three blind mice?, errant genetic marker?, elitist propagation of non-lab math-wise researchers wet dreams?) Why is string theory still here?
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