# Articles

How long does it take for one person to infect another?

The doubling time for the Omicron variant seems to be scarily fast. But how do you calculate it?

How does a smooth flow suddenly become turbulent? The Reynolds number helps understand the transition.

Markov chains are exceptionally useful tools for calculating probabilities, and they might increase your chance of getting to the beach!

How does water, or indeed any fluid, move? The Euler equations let us look beneath the surface and mark the beginning of modern fluid dynamics.

Some basic trigonometry can deliver vital evidence from the scene of a crime.

A bit of graph theory can help to identify key players in a criminal network.

Should we again reduce our social contacts? Is vaccinating 12-to-15-year-olds effective? What about boosters? The *ready reckoner* helps provide some answers.

There are many ways of explaining technical ideas, and using a range of strategies can give the most intuitive understanding.