I love this one. Really, it's maths not physics, but there is a bit of experimental physics creeping in at the fringes when the experimenters realize that the first method is biased. The second method is much better designed. Regrettably, pi-day (March 14th, 2015, or 3.14.15) only works if you use the US system of […]

Continue reading# Tag: maths

## How high is a winning cricket score?

I can't help thinking that the West Indies team got their run chase strategy wrong on Sunday night. They had a tricky task ahead of them. One might say the problem was one of their own making, judging from the rubbish that they served up to Guptill to hit at the end of tne New […]

Continue reading## The difference between a theoretical physicist and a mathematician is…

A mathematician can say what he likes… A physicist has to be at least partly sane J. Willard Gibbs What is it that makes a physicist sane (if only in part)? Everything has to be related back to the 'real world', or the 'real universe'. That is, a physicist has to talk about how things […]

Continue reading## When energy conservation doesn’t add up (or does it?)

In the last few weeks holes have been popping up all over Cambridge. They are being dug by 'ditch-witches' – pieces of machinery designed for making small-diameter tunnels for cabling – as part of the installation of fibre-optic cables for the much vaunted ultra-fast broadband. A ditch-witch is about the ultimate in machinery-obsessed-toddler heaven. We've […]

Continue reading## Saddle-points and today’s weather

I've been following the weather with interest this week. First of all, I was very glad when the wind and rain disappeared late last weekend. We were at a wedding in Whakatane on Saturday afternoon/evening, and boy, did it rain. With the wedding in a garden in something that was a bit more substantial than […]

Continue reading## Check those approximations

A common technique in physics is 'modelling'. This is about constructing a description of a physical phenomenon in terms of physical principles. Often these can be encapsulated with mathematical equations. For example, it's common to model the suspension system of a car as two masses connected by springs to a much larger mass. Here, the […]

Continue reading## Password entropy

As part of some 'NetSafe' training, I was shown this lovely xkcd cartoon http://xkcd.com/936/ . Password entropy. That's a good way of putting it. The statistical mechanics definition of entropy would be k ln W, where k is Boltzmann's constant, W is the number of permutations possible, and ln is 'the natural logarithm'. Higher […]

Continue reading## Scholarship Physics, 2013-style

Last year, Sam Hight and I made a collection of videos on tackling the 2012 Scholarship Physics exam. Well, to be precise, Sam did the videoing, editing, and distribution, and I just did the exam. The key thing, though, was that I did the exam 'live'. I was seeing the questions for the first time. […]

Continue reading## When stationary is fast

One of the great lines on the cult BBC show 'Red Dwarf' goes (approximately, from memory) like this: Can't you go any faster, like so we're not being overtaken by stationary objects? I'm sure my youngest sister would be able to correct the wording, and tell me immediately which episode it's from, who says it […]

Continue reading## The earth’s magnetic field: much more complicated than you might think

At the recent NZ Institute of Physics conference, we were treated to a wonderful description of the earth's magnetic proceses, by Gillian Turner. What makes up the earth's magnetic field? What effect does it have? How is it changing? At first glance the magnetic field of the earth is pretty straightforward. There's a magnetic north […]

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