According to Wikipedia, the first attested use of the word 'jiffy' was in 1780 and it has been suggested that it was originally thieves' cant for 'lightning'.
Wikipedia gives several other examples where this word has allegedly been used scientifically to denote a specific period of time – which just goes to show that there is no consensus on its usage and question setters should tread carefully. They include:
| • | the period of an alternating current power cycle (1/60 or 1/50 of a second in most mains power supplies) |
| • | in computing, (effectively) the smallest period of time recognised by a computer – which varies from one hardware platform to another |
| • | in computer animation, a way of defining the interval between frames – a jiffy being 10 milliseconds or one hundredth of a second |
| • | in astrophysics and quantum physics, that time it takes for light to travel a distance of one fermi. A fermi is defined as 10–15 metres, which is approximately the width of a proton or a neutron (collectively known as a nucleon) |
Wikipedia attributes the usage mentioned in my main page – being the time taken for light to travel one centimetre in a vacuum – to the American physical chemist Gilbert Newton Lewis (1875–1946).
© Haydn Thompson 2021