Tea = MC Squared

Isaac Newton is famous for some of the greatest scientific discoveries in the history of mankind: the theory of gravitation, inventing calculus, the laws of motion as written in ‘Principia Mathematica’ and demoting the Earth’s status from the centre of the universe to a simple planet in a defined elliptical orbit. But who would have thought that he, and many other classical scientific theories, could contribute to answering one of Britain’s most divisive questions: how to make the best cup of tea.

1. Never boil twice.
   In 1946, George Orwell wrote what was then the definitive guide in how to make “A Nice Cup of Tea”. What he didn’t insist upon was that the water in a kettle should only be boiled once, something William Gorman, chairman of the Tea and Infusions Association, warns is ‘crucial’. A second boil is claimed to remove chemical constituents (including oxygen and nitrogen) that leads to a flat cup of tea and a duller drinking experience. Instead of wasting water, Mr Gorman suggests using a microwave to heat up subsequent cups of tea. Whilst many will gasp at such a concept, there is method in the madness as a microwave applies the collision theory to liquids, heating them up without any change in composition or taste.
2. Milk first or last?
   Newton’s theory of cooling states that how fast a substance cools depends on the difference in temperature between the substance and its surroundings. A boiling cup of water therefore cools much faster than a cooler cup of water. So, those in desperate need of a quick cup of tea might want to consider waiting for the tea to cool down before adding milk. Alternatively, for those desiring a longer tea break, adding the milk first will ensure the tea stays warmer for longer.
3. Don’t walk and tea.
   There’s a reason why cups of tea are notoriously easy to spill. Brian Cox’s ‘Infinite Monkey Cage’ adequately describes that a cup of tea possesses an innate ‘slosh rate’. Imagine sitting on a park swing and being pushed just as you reach your highest point. Now imagine when you reach the top on the other side, you’re pushed again. The frequency of being pushed is directly matched by your natural swinging frequency and after a while you’ll be reaching ridiculous heights. Well, this is exactly what happens when you walk with a cup of tea. The frequency of the average human’s walk directly corresponds to a cup of tea’s sloshing rate. So, when doing the next tea run do just that: run.

George Orwell wrote “the best manner of making tea is the subject of violent disputes”. Perhaps now we can use fundamental science to settle those disputes and perfect those 60 billion cups of tea made in Britain every year.

Those applying for Natural Sciences might want to consider why water boils faster at higher altitude and the topic of simple harmonic motion. The ‘Infinite Monkey Cage’ podcasts are available on the BBC Radio 4 website.