Perceptions of physics

What do people think of when they hear the word “physics”? . When I tell people that I’m studying physics (I’m doing a PhD in non-linear optics and semiconductor physics at the University of Sheffield), responses vary from “I don’t like physics, it’s too hard” to nervous laughter and backing away. I think the perception of physics as hard and boring comes from not really knowing what it is.

Reflection in a soap bubble

At GCSE level, chemistry is the science with powders, colourful solutions and explosions; biology is the one about animals and plants; and physics is a miscellaneous collection of waves, electronics and Newton’s laws of motion. These are all interesting areas but because of the breadth of physics there is not enough time to explore topics at much depth. Lists of formulae need to be memorised for each different topic but a deeper understanding would reveal the links between topics so there is less to learn.

What is physics?

Physics is about finding patterns based on observations and experiments and using them to explain or predict the behaviour of different systems. For example, Archimedes said “any body wholly or partially immersed in a fluid experiences an upward force (buoyancy) equal to the weight of the fluid displaced”. This principle explains how boats float. It is used in a test of the iron levels of blood donors before they are allowed to donate to ensure that they won’t become anaemic as a result of the donation. A small droplet of blood is dropped into a solution: if the density of the blood is less than that of the solution it will float. The blood density increases with iron level, so the sinking of the droplet indicates that the iron level is high enough and it is safe to donate.

Physics can explain observations across the sciences, including topics traditionally associated with chemistry or biology. To be clear, I am not saying that other science fields are redundant because they are covered by physics. The laws of physics apply here and we can use them to predict the behaviour of some systems, but if the system is complicated (say, a group of 1000 atoms) and we can’t simplify it with approximations (which we can do in many situations but by no means in all) we just don’t have the mathematical tools required to work out the behaviour from first principles.

Who would have thought it, different problems need different approaches to solve them! We artificially separate science subjects into maths, physics, chemistry, biology and engineering, but each of these areas overlaps with all of the others, they just take different approaches which complement each other to give us a fuller picture.

Physics is hard?

Yes, of course it is. But is it harder than other vocational or academic subjects? I don’t think so. Going back to GCSE level, the aspects of physics which make it appear hard are probably the fact that it’s made up of many topics, all of which have their own set of formulae; and the mathematical content.

The difficulty with the maths is that if you don’t know how to solve a problem, there is very little you can do about it but if you can remember the methods, you will probably get the correct answer. If you understand why the methods work, you don’t even need to memorise all of them!

On the other hand in a subject such as English (the subject I found hardest at GCSE), you would probably be able to attempt an answer to most questions; whether you can analyse the themes, language and use of imagery in the text and write a well argued essay on the subject is another matter entirely! Doing English well is at least as hard as physics, but progress is incremental so it always feels like you’re improving. With maths and physics, understanding happens in jumps, but if there’s a long time between jumps, students can feel they will never understand so become put off.

Physics is boring?

No, of course it isn’t! But at GCSE level maybe it can be as there isn’t time to do any more than skim the surface. If students don’t know there’s going to be more to it than that they won’t choose to pursue it further, so this will be their last impression of the subject.

From something as exotic as the manipulation of individual electrons and photons (particles of light) to everyday things such as understanding how soap helps to remove dirt (these may reappear in a future blog post), there is surely something in physics to interest everyone.

Jasmin Chana

Soap bubble image:  © Brocken Inaglory. The image was edited by user:Alvesgaspar via Wikimedia Commons