Feynman: on physics learning …there is this possibility: after I tell you something, you just can’t believe it. You can’t accept it. You don’t like it. It’s a problem that physicists have learned to deal with: they’ve learned to realise that whether they like a theory is not the essential question. Rather it is whether or not the theory gives predictions that agree with experiment. The theory of QED describes nature as absurd from the point of view of common sense. And it agrees fully with experiment. So I hope you can accept Nature as she is…absurd.
Richard Feynman (1985)
Among the most mathematical of all subjects, apart from mathematics and statistics ofcourse, is Physics. Many students find physics difficult, as compared to say Chemistry or Biology. The general perception is that more girls find this subject difficult as compared to boys. That is surprising, because in academics, there are an almost equal number of men and women teachers of physics. So, what is it that makes Physics a ‘difficult’ subject?
I put forward the following thoughts, based on my teaching experience. A subject like biology requires memorization of many facts. Sure, there is a lot to explain and understand, but generally students find that they can manage to score well in biology by memorization. There are almost no calculations, graphs, no numerical problem to be solved, at least in the higher secondary courses. In chemistry, memorization again plays an important role, although less as compared to biology. One must understand the chemical equations, electron structure, etc, but many students find chemistry also ‘manageable’.
So what happens with Physics? Here are a few reasons why physics is not loved too much:
- Conceptually more demanding.
- Every concept/topic involves thinking at many levels
- Experiments must be performed, and results correlated with theoretical values
- Calculations of errors
- Deal with numerous units of physical quantities
- Representing results numerically and graphically
- Interpretation of graphs
- Tables of numbers like trigonometric and logarithmic tables
- Give reasons that tally with physical, real-world observations
- Remember definitions and laws
- Too many formulas to learn
- Too much theory – laws, hand rules, treating quantities as vectors or scalars, dealing with concepts that are not ‘obvious’.
- Transfer from graphical to mathematical representation and vice-versa
- Physics is not just about physics; you have to also use algebra, geometry, calculus and so you have to be reasonably good at these other subjects also
- Some topics in physics are abstract and maybe student cannot relate with those immediately, like quantum mechanics and atomic physics
- Physics is taught at a faster rate compared to languages and social sciences.
- Physics can demand that you start with a specific result and make general rules
- Not reading the text and not solving exercises makes understanding almost impossible
- Often, the numerical problems solved are substitution type problems, like F = ma, given F and M, find a. Students are led to believe that physics involves such calculations. We know that’s not true. The more difficult problems are never taken up and more difficult topics are kept as an ‘option’, and these are the topics that are required for further study.
- The basics of drawing and interpreting graphs are often very weak and so are the basics of calculus. So while a student may know how to find a derivative, she may not have been told of the connection between a derivative-slope-velocity, and area under a curve-integral, etc. This difficulty arises because the teacher teaching mathematics often doesn’t have to discuss applications of calculus to other subjects, and physics teacher expects (sometimes) the math teacher to discuss this.
- It is quite possible that physics isn’t being taught the way it should be taught. Now that wouldn’t be students’ fault. But the student still suffers. Numerous studies have shown that there are many misconceptions that students have and unfortunately, these misconceptions are not being addressed.
Physics is cumulative. If you have not understood the basic concepts, and yet managed to pass your exams, this deficiency will soon catch up as you study more of physics. So you must not ignore the basics. Competitive exams don’t test only textbook knowledge, they test you on applications. Application-oriented problems can only be solved if fundamentals are clear, and you improve skills with mathematics, graphs, interpretation and logic. Once you know why a subject appears to be difficult you can work your way to make it easy, interesting and useful.
The reason physics is difficult is that classical physics is based on the analysis of differential equation models of physical processes. There are two problems, first, some differential equations are difficult to solve, the second problem is worse, most of the differential equations that aren’t difficult to solve are impossible to solve, that is, no analytic solutions exists. That’s the reason physics is difficult. Exhibit #1 – a high school student learns the laws of gravity and motion, and derives the differential equation for the acceleration of a falling object in a gravity field. The equation is dropped like a hot potato, and the student will not see a solution in high school or university. Here’s why – see the section ‘inverse square law gravitational field’ in the wiki entry for freefall to see the solution. Unsolvable differential equations are the unseen elephant in the room in physics education.