### Information Theory

That’s Maths in The Irish Times this week (TM059, or Search for “thatsmaths” at irishtimes.com) is about data compression and its uses in modern technology.

Left: An equation form Shannon (1948), the paper that launched Information Theory.

### New Curves for Old: Inversion

Special Curves

A large number of curves, called special curves, have been studied by mathematicians. A curve is the path traced out by a point moving in space. To keep things simple, we assume that the point is confined to two-dimensional Euclidean space ${\mathbb{R}^2}$ so that it generates a plane curve as it moves. This, a curve results from a mapping ${\mathbf{\gamma} : [a,b]\longrightarrow \mathbb{R}^2}$. Continue reading ‘New Curves for Old: Inversion’

### The Year of George Boole

This week’s That’s Maths column in The Irish Times (TM058, or search for “thatsmaths” at irishtimes.com) is about George Boole, the first Professor of Mathematics at Queen’s College Cork.

### Falling Bodies [2]: Philae

The ESA Rosetta Mission, launched in March 2004, rendezvoused with comet 67P/C-G in August 2014. The lander Philae touched down on the comet on 12 November and came to rest after bouncing twice (the harpoon tethers and cold gas retro-jet failed to fire).

Comet 67P/Churyumov-Gerasimenko on 11 August 2014. The landing site is on the smaller knob, near the top of the image. Photo copyright ESA.

### Earth’s Shape and Spin Won’t Make You Thin

Using a simple pendulum we can determine the shape of the Earth. That amazing story is told in this week’s That’s Maths column in The Irish Times (TM057 or search for “thatsmaths” at www.irishtimes.com ).

Is the Earth oblate like an orange (Newton) or prolate like a lemon (the Cassinis)?

### Falling Bodies [1]: Sky-diving

Aristotle was clear: heavy bodies fall faster than light ones. He arrived at this conclusion by pure reasoning, without experiment. Today we insist on a physical demonstration before such a conclusion is accepted. Galileo tested Aristotle’s theory: he dropped bodies of different weights simultaneously from the Leaning Tower of Pisa and found that, to a good approximation, they hit the ground at the same time.

Aristotle and Galileo.

### El Niño likely this Winter

This week’s That’s Maths column in The Irish Times (TM056 or search for “thatsmaths” at irishtimes.com) is about El Niño and the ENSO phenomenon.

In 1997-98, abnormally high ocean temperatures off South America caused a collapse of the anchovy fisheries. Anchovies are a vital link in the food-chain and shortages can bring great hardship. Weather extremes associated with the event caused 2000 deaths and 33 million dollars in damage to property. One commentator wrote that the warming event had “more energy than a million Hiroshima bombs”.

Patterns of Pacific Ocean sea surface temperature during El Niño and La Niña episodes. Image courtesy of Climate.gov.