Happy New Year!
Each New Year is an opportunity to look back at the previous year, anticipate the future year and perhaps make resolutions to improve our lives, or even of those of people around us. Maybe this is even more true this year which is not just the start of a year, but of a decade.
This year I have been lucky to meet, or to continue friendship with, many people who have taught me all sorts of things about life, physics and coffee. There have also been some great finds of some fantastic cafes, trying to make a difference to their local community while serving excellent coffee.
And yet, as the year or the decade turns and we resolve to get fitter, pay more attention to sustainability or whatever seems important to us right now, we will inevitably take our existing selves into the new day and our resolutions will meet the reality of who we are: a bell rings at certain frequencies owing to the resonances of the vibration on the surface of the bell. The resonances of the bell depend on its exact shape and size, it is not easy to change the sound of the bell unless you change its temperature or even the interior to a different gas or muffle. (You can see images of how a violin vibrates at resonance here). The surface of a coffee resonates similarly, if we put it on a vibrating surface with a frequency that matches the fundamental vibrations of the surface. Nonetheless, thinking about these resonances can take us in surprising directions. The mathematics that describes them was developed by Friedrich Bessel (1784-1846) but, Bessel was not thinking about resonances when he formulated what is now known as Bessel functions. And it is possible, his life may have taken a very different direction were it not what happened from 1799.
In the new year of January 1799, when he was just 14, Bessel was apprenticed to an imports and exports company with the hope that he would become an accountant. And maybe we would have heard no more about him had he not got interested in the problem of longitude and solving the navigational issues of the time, important for the company for which he was working. This issue got him thinking about astronomy and he caught the attention of the authorities of an observatory who gave him a job there and encouraged his observations and interest. But it was while thinking about “many body problems” or how multiple massive objects interact with each other via gravity that he came up with the mathematical description that we now know as Bessel functions. It is these Bessel functions that also describe the resonances on a bell and in a coffee cup.
What does this leave us with in our thoughts for 2020? That what we are interested by may lead us to discoveries in various tangential and scarcely believable connections? That what we plan for our lives may not be how they have to end up? That it benefits us to stop for 5, 10 minutes, even half an hour and just contemplate our world in our coffee? (ok, that last one did not come from Bessel). Where-ever your paths lead and your interests lie, happy new year! May the 2020s be a decade where we can all slow down, notice, contemplate and appreciate the beauty of this strangely connected world which is our home.