A break from physics to show something which might be actually useful to some people. Normal service will resume shortly.

I wrote this blog post because I saw a woman throw a banana at Russell Brand. Bear with me on this one.

Recently the extractor fan in my bathroom has started malfunctioning, occasionally grinding and stalling. The infuriating thing is that the grinding noise isn't perfectly periodic - it is approximately so, but there are occasionally long gaps and the short gaps vary slightly. This lack of predictability makes the noise incredibly annoying, and hard to tune out. Before getting it fixed, I decided to investigate it a bit further.

As a poor student, I always tried to keep a close eye on what I spent. This usually amounted to skimming statements and manually keeping track of what went where, a decidedly sub-optimal solution. Thanks to an initiative called MiData, you are now able to download transaction histories from your current account in CSV format, which is ripe for analysis. I built a small tool for myself, which I put online here for your enjoyment. I should note this is the first slightly complex thing I've written in Javascript, so if it breaks in unexpected ways feel free to get in touch and let me know.

Here's a fun problem I came across when trying to analyse some data, which I thought I'd write up to illustrate the kind of interesting puzzles I get paid to solve as a physicist. Perhaps have a go yourselves and let me know if there are more intuitive solutions.

In this third of a trinity of posts involving the travelling salesman problem, we finally use the sophisticated algorithms at our disposal as they were intended: drinking with peak efficiency. With the aid of a well-placed Christmas present detailing the best pubs in London, I found the optimal route around a reasonable subset of them.

This is the second in a series of posts involving the travelling salesman problem, somehow even more frivolous than the first. This is no coincidence, as I have recently been reading the excellent book 'In Pursuit of the Travelling Salesman', which goes into great detail on the history of the problem and algorithmic techniques for tackling it. The topic which caught my eye was decidedly less technical, as we shall see below.

In the finest traditions of christmas, how about a timely blog post meant to cynically cash in on a blogosphere craving seasonal articles about nothing much in particular (see previous, sadly failed, attempt). What are the implications of Santa flying around the UK in a single night?

I saw a 'simple' puzzle on the internet which I thought I'd have a crack at in an evening. Several furious scribblings on the bus and the sofa later, I finally have an answer. I'm so relieved I can't help but share the joy.

Way back when I was analysing London house price data for the Summer Data Challenge, I made a histogram of the distances from a random point in London to the nearest tube station. I noted that it peaked around half a kilometre, but ignored the shape of the distribution itself. This is an unfortunate faux pas for the accomplished procrastinator, so let's right that wrong with the help of some stochastic geometry.

Here's a post which combines my favourite bits of writing a blog - fairly mathematical, not too simple or difficult to implement, mostly based around pictures, not covered in my undergraduate education, and pretty damn useful in my job. Excited? You should be.

The last time I looked at house prices it went pretty well, and I ended up winning a data science competition. There I was only dealing with a million or so records, and a relatively small 120 MB dataset. Then I found out it was possible to download 3.7GB of property sale records for all of England and Wales since 1995, so let's have another go.

This blog has been getting a bit too pop-science for my tastes recently. Card games? Word clouds? Urgh. Let's do some proper physics. I hope you're paying attention at the back.

When taking a picture of my new 55" TV (humblebrag) I noticed a diffraction pattern of the reflection of the camera flash. Fortuitously, I had also recently bought a slightly too-powerful laser pointer from China which is the perfect tool to investigate such problems. Here's a little write-up of my DIY measurements.

It's done! After 58,627 words, 233 pages, 369 references, 162 figures and 3 lonely tables I finished my PhD thesis. Weighing in at 161.8MB, it was unceremoniously uploaded and that was that. Here are a few tips and observations I made on the way, which are probably only useful to those of you battling through a long Latex document. Never fear, normal blogging service will resume shortly.

A quick note this time, compiled entirely over a course of a 45 minute train journey, but nevertheless with some cool pictures.

I've been a little busy recently for blog posts, what with a pesky thesis to finish and all, but such an occasion as this deserves the highest honour possible - making lots of plots. That's right, the hallowed HTML files under this domain name have been yanked from a poor Wordpress server somewhere over 1 million times now, almost coinciding with the first anniversary of the blog. I think it's a useful event to prompt some details for those of you interested in the business of blogging - who knows, perhaps you'll start one of your own?

Holidays are so relaxing. You know the drill: lounge around, eat and drink haphazardly, play card games, simulate several million card games to gain an advantage over your opponents, go for walks, visit the seaside, derive relationships for expected values of card hands, buy chocolates, smash unsuspecting opponents through brute force, send a postcard, etc. etc.

Given a few of my previous posts it's obvious that I'm a fan of the physics and mathematics that that comes along with the theory of classical optics. To make the number of lens-based posts a nice round three then, here's a simple Matlab App I made over the last few days which lets you play with lenses interactively, hopefully giving a bit of useful insight into the underlying principles.

Over the last few years I've been working towards a PhD in the realm of experimental physics. This, naturally, requires experiments to occur. As good scientists we (ideally) record all the details of the experiments, which makes for a tasty dataset after a few years. Let's have a look at some details.

A puzzle has been floating round the internet, apparently impossible and assigned to 8-year olds in Vietnam. How impossible is it? Here's a quick look.

I am a short man. I have an even shorter girlfriend. Odds are, any offspring would be short. Odds are, their partners would be similar or smaller in height, especially if they are male. Does this mean I am destined to be the heir to a slowly shrinking troglodyte race, my pristine DNA squirted from troll to troll until it degrades to a corrosive, fetid broth? Let's put the thesaurus away and have a look.

In my last blog post I waded through a lot of maths with no pretty pictures to show for it. I'll redress the balance here and make the pictures extra pretty. The post title alludes to a previous post, and is similar in that I'll be using mathematics to form interesting 3D objects.

I've talked before on this blog about the propagation of electromagnetic waves, and that's not stopping any time soon. This time, I'd like to go through from first principles and demonstrate how a lens forms an image in all the gory details. Beware, there be maths ahead...

What does this title mean? What's with the recent bus obsession? Is this post even about buses, or are they just being carelessly shoehorned into every post title from here on out? Excellent questions, thanks for asking. Allow me to explain.

As the old saying goes, you wait ages for a bus and then two come along at once (or more!). Is this true though? My own anecdotal evidence would suggest yes, every single bloody time. However, we love data and maths in this blog almost as much as we hate waiting for the bus, so let's have a more thorough look at the issue.

I was playing pool recently, rather badly, and remembered it was much easier to play on a computer, when one can look down on the table from above and see where the balls are more easily. Wouldn't it be great if there was a way to see this in real time when playing pool? I haven't done that here, yet, but lets have a look at the steps which might be involved in a solution.

Paul the octopus, for the unaware, was a true hero of the modern age. Combining cephalopodian good looks with a pragmatically sensible German name, he was the star of the show at the Oberhausen Sea Life Centre. That is, however, until his tragic passing in 2010, when the world lost one of its most famous psychic entities. Over the previous two year period, Paul correctly guessed the outcomes of 12 out of 14 international football matches. Does this merit his psychic status? Let's investigate, following this great example from the excellent book 'Statistical Inference for Everyone' by Brian Blais.

Continuing on from my last post concerning optimisation and Lagrange multipliers, I came across a neat little paper on the arXiv here, which asks and answers the question: what shape should a planet be to maximise the gravitational force at a given position? This is a fun problem, solved using an extension of the techniques from the last post, namely the use of Lagrange multipliers to optimise a function given some constraint.

It's that time of year again where I am forced to come face to face with my one and only flaw: wrapping presents. Yes, the great staff of Debenhams may as well be superheroes to me, expertly taping seams and tying ribbons while I look on with envious bewilderment. My efforts in comparison look like they've washed ashore after six months at sea due to a tragically festive shipping accident. In an attempt to reclaim some Christmas pride then, let's see if there is anything interesting in the present wrapping process, without, you know, actually doing any wrapping.

I was recently at CERN for one of their accelerator schools, learning about new and potentially disruptive plasma-based particle accelerator technology (disclaimer alert - the subject of my PhD). In honour of such a famous institution, I though I'd write about the worst enemy of CERN (and the friend of plasma accelerators) - synchrotron radiation.

I was reading the other day about the Tube Challenge, where people attempt to visit all 270 stations on the London Underground in the quickest possible time. Apparently successful routes are a closely-guarded secret, which got me thinking about how difficult an optimisation problem it must be to find the best route.

I saw an article on the Guardian website here on the 3D-printing of shapes which project interesting patterns of light. Ignoring the strangely forced Halloween reference, I thought this would be an interesting project to attempt for an arbitrary pattern, perhaps as a personalised lampshade. Buoyed by the continuing high of leftover sweets from Friday night, let's have a look.

A while back I heard about the Summer Data Challenge, hosted by my university. A number of datasets are available to download and analyse, and I chose to look at data on the selling price of properties in London over the past 5 years. I've assembled a number of plots here in order to examine this slightly cumbersome dataset more easily.

Diseases have been in the news recently, for one reason or another, and journalists are engaged in an increasingly ridiculous race to construct the most alarming headlines possible. How about we cut through the noise and indulge in a calming bit of maths?

I remember seeing once the following photo from Flickr, and having my brain melt slightly from trying to figure out what went wrong: The issue was the propeller was rotating as the camera detector 'read out', i.e. there was some motion during the exposure of the camera. This is an interesting thing to think about, lets have a look.

From a recent post I've had the scripts lying around to calculate the trajectories of particles around black holes. The paths were pretty crazy, which got me wondering what such a system would look like. For that I need to calculate how photons move around black holes, which is a slightly different problem, and doesn't offer up much in the way of puns for post titles...

If you're anything like me, the excruciating boredom of a trip to the supermarket is enough to get you thinking about anything else, in a desperate attempt to avoid a conversation on the best value lettuce on offer. I'll do you a favour then by presenting some brain-fodder suitable for the next grocery hell-ride.

What's in a rainbow? Fairytales and pixie dust? Gold and leprechauns? A boatload of drugs? Nope, just clear cold geometry and physics, just how we like it.

I've spend an unreasonably significant fraction of my life sitting in traffic, particularly along the infamous M4 corridor in England. Now, living in London I'm well acquainted with the various ways traffic jams can form. The ones which result from stuffing too many cars into too tiny streets have an obvious cause. Somewhat more irritating are those forming for seemingly no reason out on the motorway - queueing for ages at a standstill only to suddenly drive away like nothing happened. I've spent enough time in this unenviable state that it's almost (though inevitably not quite) worth dedicating some brain time to thinking about why.

During one of my many spells stumbling around on the internet, I came across a very cool paper on modelling the trajectories of particles around black holes (bear with me...). It has all the required ingredients for this blog: maths, physics, nice pictures, and the chance to throw in a Muse reference. Let's have a look.

The Android app below will no longer receive updates, but you can access an improved online version at https://wifi-solver.com !

A few posts back I was concerned with optimising the WiFi reception in my flat, and I chose a simple method for calculating the distribution of electromagnetic intensity. I casually mentioned that I really should be doing things more rigorously by solving the Helmholtz equation, but then didn't. Well, spurred on by a shocking amount of spare time, I've given it a go here.

I've been experimenting with my data presentation recently, trying to make it a bit more 'fun' (read - epic procrastination which has a thin questionable veneer of usefulness). In the post below I'll talk about how I had a go at getting some data away from the awful, awful, plotting abilities of Matlab, and getting it into Blender.

We'll continue the theme of this fledgling blog along the lines of fractals, pretty pictures, spirals and Matlab. All of this neatly encapsulated in the concept of the damped and driven oscillator, alluded to somewhat scandalously in the title. In particular, for simplest conceptualisation (and maximum innuendo potential) we'll look at the humble pendulum.

I was told an example interview question involving ants following one another around in a square, and it continued to bug me for a while (pun wholeheartedly intended). The specific wording of the problem is this: 4 ants are place at the corners of a square of unit area, and each ant walks towards the ant ahead of it. What is the shape of the path the ants take, and how far do they walk until they meet? Sounds fun and relatively simple (though not so much in an interview situation!), lets have a look.

When initially fiddling around and getting to grips with Matlab a while ago, I had a go at implementing the 'logistic map', a well known mathematical process which leads to deterministic chaos. http://en.wikipedia.org/wiki/Logistic_map

To simulate your own WiFi signal, check out: https://wifi-solver.com ! I've recently moved into a new flat, and to celebrate I bought a WiFi card for my PC rather than relying on a power line LAN adaptor - plug sockets are a valuable resource in a Victorian flat conversion and so shouldn't be wasted on such trivial things. Unfortunately, with my lovely new card freshly installed my connection was erratic at best, disconnecting more or less at random and generally being a first-class first-world problem. In a fit of internet-deprived mania I decided to investigate, the first act being to crash out a quick CAD drawing of the flat layout in Sketchup:

The above image is of a few iterations of a Newton fractal. Assuming that isn't quite enough information for you, a Newton fractal is a 2D plot of the complex plane - that is to say real numbers along the horizontal axis and imaginary along the vertical - where each point is coloured by the value of a complex number there. http://en.wikipedia.org/wiki/Newton_fractal