Geodesy is the study of the shape and size of the Earth, and of variations in its gravitational field. The Earth was originally believed to be flat, but many clues, such as the manner in which ships appear and disappear at the horizon, and the changed perspective from an elevated vantage point, as well as astronomical phenomena, convinced savants of its spherical shape. In the third century BC, Eratosthenes accurately estimated the circumference of the Earth [TM137 or search for “thatsmaths” at irishtimes.com].

## Archive for the 'Irish Times' Category

### Fourier’s Wonderful Idea – II

Published April 5, 2018 Irish Times Leave a CommentTags: Analysis, History

**Solving PDEs by a Roundabout Route**

Joseph Fourier, born just 250 years ago, introduced a wonderful idea that revolutionized science and mathematics: any function or signal can be broken down into simple periodic sine-waves. Radio waves, micro-waves, infra-red radiation, visible light, ultraviolet light, X-rays and gamma rays are all forms of electromagnetic radiation, differing only in frequency [TM136 or search for “thatsmaths” at irishtimes.com].

### Cubic Skulduggery & Intrigue

Published March 15, 2018 Irish Times Leave a CommentTags: Algebra, History

Babylonian mathematicians knew how to solve simple polynomial equations, in which the unknown quantity that we like to call *x *enters in the form of powers, that is, *x* multiplied repeatedly by itself. When only *x* appears, we have a linear equation. If *x*-squared enters, we have a quadratic. The third power of *x* yields a cubic equation, the fourth power a quartic and so on [TM135 or search for “thatsmaths” at irishtimes.com].

### Reducing R-naught to stem the spread of Epidemics

Published March 1, 2018 Irish Times Leave a CommentTags: Epidemiology, medicine

We are reminded each year to get vaccinated against the influenza virus. The severity of the annual outbreak is not known with certainty in advance, but a major pandemic is bound to occur sooner or later. Mathematical models play an indispensable role in understanding and managing infectious diseases. Models vary in sophistication from the simple SIR model with just three variables to highly complex simulation models with millions of variables [TM134 or search for “thatsmaths” at irishtimes.com]. Continue reading ‘Reducing R-naught to stem the spread of Epidemics’

### Galileo’s Book of Nature

Published February 15, 2018 Irish Times Leave a CommentTags: Astronomy, History, Mechanics

In 1971, astronaut David Scott, standing on the Moon, dropped a hammer and a feather and found that both reached the surface at the same time. This popular experiment during the Apollo 15 mission was a dramatic demonstration of a prediction made by Galileo three centuries earlier. Galileo was born in Pisa on 15 February 1564, just 454 years ago today [TM133 or search for “thatsmaths” at irishtimes.com].

### Staying Put or Going with the Flow

Published February 1, 2018 Irish Times Leave a CommentTags: Algorithms, Geophysics, Numerical Analysis

The atmospheric temperature at a fixed spot may change in two ways. First, heat sources or sinks may increase or decrease the thermal energy; for example, sunshine may warm the air or radiation at night may cool it. Second, warmer or cooler air may be transported to the spot by the air flow in a process called advection. Normally, the two mechanisms act together, sometimes negating and sometimes reinforcing each other. What is true for temperature is also true for other quantities: pressure, density, humidity and even the flow velocity itself. This last effect may be described by saying that “the wind blows the wind” [TM132 or search for “thatsmaths” at irishtimes.com].

### The Heart of Mathematics

Published January 18, 2018 Irish Times Leave a CommentTags: biology, Fluid Dynamics, medicine

At five litres per minute the average human heart pumps nearly 200 megalitres of blood through the body in a lifetime. Heart disease causes 40 percent of deaths in the EU and costs hundreds of billions of Euros every year. Mathematics can help to improve our knowledge of heart disease and our understanding of cardiac malfunction [TM131 or search for “thatsmaths” at irishtimes.com].