Why study physics?

This question is probably asked several thousand times a day by children around the world. Physics is undoubtedly an important subject - modern lifestyles are based largely on the advances that the science has brought about. However, I think reasons other than its practical applications are often ignored, and it is these I shall now address.

The first is simply a desire to further our understanding of the universe, for no other reason than a thirst for knowledge. This might seem cliché, but it motivates many people who devote their lives to the study of the sciences. Humans are curious creatures, so it is natural to seek answers to the fundamental questions - “How come we exist?” and “Why do we exist?” to name but a couple. We don’t yet know the answers, and of course it is entirely possible that we never will, but physics gives us a logical and methodical framework with which to address them. It is this that makes physics attractive to those who seek knowledge, understanding and answers, and makes a very good reason to study physics on a long term basis.

For many of us though, a lifetime in research isn’t an option, as we have other interests we want to pursue. So why study physics in this case? One very good reason is that the skills you acquire are readily transferable; it is often said that physics graduates are among the most widely employable due to this. Physics contains a very strong mathematical element (which in itself is useful), but solving problems is more than just mathematics. A “physicist’s intuition” may be a myth, but it is true that physics teaches you to apply a set of rules to an unfamiliar situation, and work out what will happen. Lab work also teaches you more than just physical laws - how to work to a tight schedule, deal with unfamiliar equipment and co-operate with fellow students whilst under pressure. All very useful skills!

Finally, physics is easy! This isn’t of course a reason in itself, however I’m sure a lot of people are put off reading into the subject due to this misconception. In case you aren’t convinced with this assertion, I will try to persuade you. Consider “rocket science”. It is common phrase used to describe anything that is incomprehensible. But in actuality, rocket science itself is surprisingly simple. All we do is apply Newton’s 3rd Law of Motion - that every action has an equal and opposite reaction. A rocket propels hot gases out of the back, and so moves forward - essentially this is all the equations say! (Of course, sometimes you need to take into account air resistance etc., but this also is not hard to write down) At this point we move from the realm of physics to mathematics, and solving these equations can be tricky. However, it is perfectly possible to study and understand physical principles without doing difficult maths.

So there you are - study physics! Thanks for reading, and watch out for updates.

A question of energy

Everyone has heard of energy - it forms the underpinnings of today’s society, all life forms, and indeed the universe as we know it. But do we actually understand it?

The first mention of the term ‘energy’ is thought to be by Aristotle, from the Greek which translates literally as “at work”. In fact, this translation is remarkably close to the definition given in many school textbooks: that energy is the capacity for doing work. What do we mean by ‘work’ in this context? Lifting a weight, powering a light bulb and pumping a balloon are all examples, but unfortunately there is no way to define something as being ‘work’, without making a circular argument linking back to energy.

Most of us will stop here, and stick with the intuitive notion of energy that is associated with doing work. But we can do better than that! The best way to proceed is to run with the term ‘energy’, and see if we can find any properties of this stuff. Well, it turns out that we can, and the most important of these is the law of conservation of energy.

Conservation of energy

Conservation of energy might sound more like something from a naturalist society, but in fact it’s the foundation of modern physics. The rule is that while we can do a lot of things with energy: move it around, store it in different ways, and run our computers, we can never use it up! This might sound a bit odd at first - if not just plain wrong. You might well cite the example of a light bulb, surely since we’re shovelling electricity into it, we must be consuming energy? No! The energy is being converted, as we shall see.

Energy conversion

A very interesting property of energy is that it exists in different forms, as the following example illustrates. Suppose we have a tank full of water, and suspend it above the ground. Then we connect a pipe from the bottom down to a paddle wheel, connected to an electrical generator. This is then connected to a light bulb. If we pull the plug in the tank, what do we see? The water runs from the tank, turns the wheel, generates electricity, and the bulb lights and warms up.

Since all we do is pull out the plug, which we’ll do gently, then there must be energy stored in the system. This is called potential energy, because it isn’t doing anything at the moment but “potentially could be doing something in the future”. We could even be more specific and say that it’s gravitational potential energy, since the water gets pulled down the tube by the Earth’s gravity. If we did this in deep space, it wouldn’t work! So this our first type of energy.

Next, the water pushes on the water wheel, turning it. This brings us onto another manifestation of energy - that associated with moving objects. It is termed kinetic energy, from Greek. We know now that energy is conserved, so the water must lose some of its energy, hence slowing down (kinetic energy increases with speed), whilst the wheel gains.

By now, we can see the pattern - at every stage we take one type of energy, and move it around, or convert it. So, the generator turns kinetic energy into electrical energy, then the light bulb turns electrical energy into light and heat, both of which are types of energy - so in fact we can explain the earlier dilemna! That’s really all there is to it.

Matter as energy

Probably one of the most significant and well known breakthroughs of the 20th Century was Albert Einstein’s Theory of Relativity, and the famous equation E=mc^2. Whilst this might appear complex, it is in fact nothing more than what we described above! The formula describes a form of energy (E) that is dependent on the mass of an object (m), multiplied by a constant (c^2, where c means the speed of light by convention). Thus all objects must have energy just through existence! Converting to and from this sort of energy is difficult, and is the principle behind atomic power.

Closing remarks

That really sums up the most important principles of energy. It is true there are many textbooks on the subject, complete with intimidating mathematics, but this really is not necessary to have a sound grasp of the physics behind it. However, the question of what this thing ‘energy’ is remains unanswered, as summed up by Richard Feynman:

“It is important to realise that in physics today, we have no knowledge of what energy is” - Feynman, Lectures on Physics

And with that thought, thank you for reading, and look out for more updates soon!

Welcome

To all who have stumbled here, by accident or otherwise, might I extend a warm welcome!

The world of physics, if not science in general, is often considered to be somewhat obscure. Press releases are made about some of the most extravagant endeavours, but short of that there is little common understanding about what is involved in studying the physical world. I aim to change this.

I myself am a physicist studying in the UK, and as such have had some exposure to the academic side of physics. I will be basing my posts on personal experiences and articles I have read, but I very much intend to keep in mind the reader without extensive technical knowledge.

I hope to have my first "real" post ready this weekend, please stay tuned!