This is a post about a possible misconception about sound that can be gained from a common method of drawing sound waves. Sound is caused by vibrating objects. Those vibrations cause disturbances to the particles of the surrounding medium (air, for example). Those particles disturb their neighbours, and the disturbance propagates outwards as a wave […]

This is part 3 of a blog using artistic perspective to provide a context for discussing the relationship between special cases and general laws. You can find Part 1 here, and Part 2 here. Why are the lines straight? Imagine standing in front of a ruined section of the Great Wall of China, or Hadrian’s […]

This is part 2 of a post using artistic perspective to provide a context for discussing the relationship between special cases and general laws. You can find Part 1 here. How far apart are the vanishing points? In two-point perspective, the spacing of the vanishing points reflects how close you are to the scene. In […]

What this post is about Someone recently asked me how to draw in perspective. That was a mistake, because I am the living refutation of the encouragement “Everyone can draw.” Still, I guess the idea was that I know some physics and so must understand how 3D geometry works. So I explained about one-point and two […]

In the popular media, you often hear the phrase “the ‘something-or-other’ has grown exponentially.” Quite often in such situations, the word ‘exponentially’ is used imprecisely to mean ‘quite a lot’ or ‘rather fast’, but in science it has a very specific meaning. Exponential changes happen when the rate of change of a quantity is proportional […]

Fukushima in Japan has become newsworthy again recently. Many residents have been allowed back to their homes. In January 2019, Scientific American reported that radiation: “in some places continues to measure at least 5 millisieverts (mSv) a year beyond natural background radiation, five times the added level Japan had recommended for the general public prior […]

I was led to thinking about relative atomic mass the other day, and asked myself a really simple question that I couldn’t answer. I was slightly embarrassed that (a) I didn’t know the answer, and more importantly that (b) I’d never considered the question before. The question is “when/where do these numbers apply?” Let me […]

In our previous post, we described the use of decibels as a unit of ‘sound level’, and talked of it as a logarithmic scale, one in which equal increases represent equal multiplications of the quantity represented. In this post, we will look at another logarithmic scale, the Richter scale for earthquake magnitudes (seismologists may be disgusted […]

We have probably all seen charts of the decibel scale like the one below. But unless you know how the scale works, you might be led to think that a rock concert is twice as loud as a conversation. And instinctively, you might realise this cannot possibly be the case. This post aims here to […]

As a child, I was oddly fascinated by how ears work. I used to ask “How can we hear two things at once and tell them apart?” I still think this is a much better question than it is given credit for, one that people rarely stop to think about. And it is what this […]

This is part 2 of a primer on the standard model. If you missed part 1, you can find it here. The eightfold way Let’s begin with the mesons (pions and kaons). They have charges of +1, 0 or -1, and strangenesses of +1, 0 or -1. We can draw a chart with strangeness on […]

The final episode of our article, in which we try to develop an understanding of atomic structure and the periodic table, from the beginning of secondary school/junior-high level, to first/second year undergraduate physics/chemistry, via one fictional conversation. Find Parts 1 – 5 on our blog page. Sigrid has just asked Sally whether ‘l=0’ corresponds to the […]

In our post on anthropomorphism, we discussed benefits and pitfalls of ascribing human motivation to subatomic particles. There is a related but different phenomenon, which can occur when popular culture appropriates a scientific idea. It often happens when science uses an everyday word for a technical concept – people may then be forgiven for generalising […]

This is a piece about my favourite diagram in all of science, the Hertzsprung-Russell (HR) diagram. It’s such a cool thing, I need to stop writing and just put it here, at the top. Here it is (please do scroll down and read the post though!). This diagram describes and charts the properties of the […]

For a while now I have been telling people to read ‘Color: From Hexcodes to Eyeballs’ by Jamie Wong, on the basis that it is one of the best explanatory pieces of ‘writing with diagrams’ I have ever come across. A few of those people have given the feedback that it started at too high […]

Probably most people know that stars and planets are very different. Very different. A star is a massive collection of plasma sustaining nuclear reactions, so far away (apart from our own Sun) that its light takes many years to get to us. A planet is much smaller and is a rocky/gaseous ball that orbits our […]