Dancing by John Hawkhead

photons
E=mc²
dancing

By John Hawkhead

Photons are some of the most fascinating particles in the physical sciences; fundamental particles of light that are the smallest possible packets of electromagnetic energy.

Albert Einstein’s mass–energy equivalence (represented by the formula E = mc²) gives the basic relation between mass and energy, stating that under appropriate situations mass and energy are interchangeable and the same. Yet photons have a rest mass of zero – they are massless particles – therefore should they even have any energy at all? And if they have neither mass nor energy then would they even physically exist?

E = mc² is actually a special case of the more general equation E² = p²c² + m²c⁴, where E is energy, p is momentum, c is the speed of light and m is mass at rest. Since photons have no mass, this equation becomes E = pc.  Effectively, photons get their energy from their momentum and can never be at rest, constantly moving.

How they move has been the subject of study for decades, with recent research suggesting that photons can behave as both particles and waves (to find out more, check out the sciku ‘Spooky Interaction’, also by John Hawkhead).

This sciku plays around with the concepts of photons, square dancing and the randomness of measuring the path of photons.

Further reading:

‘Light has no mass so it also has no energy according to Einstein, but how can sunlight warm the earth without energy?’, Science Questions with Surprising Answers: https://www.wtamu.edu/~cbaird/sq/2014/04/01/light-has-no-mass-so-it-also-has-no-energy-according-to-einstein-but-how-can-sunlight-warm-the-earth-without-energy/

‘Mass–energy equivalence’, Wikipedia: https://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence

‘Does light have mass?’, Physics FAQ: https://www.desy.de/user/projects/Physics/Relativity/SR/light_mass.html

Author bio:

John Hawkhead (@HawkheadJohn) has been writing haiku and illustrating for over 25 years. His work has been published all over the world and he has won a number of haiku competitions. John’s books of haiku and senryu, ‘Small Shadows’ and ‘Bone Moon’, are now available from Alba Publishing (http://www.albapublishing.com/). Read more of John’s sciku here!

‘Dancing’ was previously published in Failed Haiku 74 (1 Feb 2022).