Fingerprints in the sky explained
Today, a group of physicists published the most compact and elegant explanation of one of nature’s simplest phenomena: the way light behaves in the sky above us. This research appears today (Tuesday, 9th November) in the New Journal of Physics, published jointly by the Institute of Physics and Deutsche Physikalische Gesellschaft (German Physical Society).
Michael Berry and Mark Dennis from the University of Bristol, in collaboration with Raymond Lee of the US Naval Academy, have successfully predicted the patterns of polarisation of skylight, explained in broad outline by Lord Rayleigh in 1871, using elliptic integrals – a type of mathematics with deep geometrical roots, often described as “beautiful”.
The blue sky seen through polaroid sunglasses gets darker and brighter as the glasses are rotated. This reveals something almost invisible to our unaided eyes: daylight is polarized light. This means that the light waves vibrate differently in different directions. The effect is strongest at right angles to the sun, and weaker elsewhere. It creates patterns in the sky that look similar to the ridges in human fingerprints and are used by many species of birds and flying insects as an aid to navigation.
A striking feature of the pattern is a pair of points near the sun where the light is not polarized at all (this point is a singularity and the pattern breaks down here). Although they have been studied for nearly two centuries, no one attempted to construct a model using the most obvious feature - the singularities - until now.
Sir Michael Berry said: “We wondered: what if you start with the singularities and write the simplest description of polarisation that puts the singularities in the right places? We found that this gives a remarkably good fit to the observational data, and predicts the pattern across the whole sky.” “This is beautiful mathematics in the sky. Using elliptic integrals, we’ve been able to replace pages and pages of formulae with one very simple solution that predicts the pattern extremely well” “After almost 200 years there’s now a way of understanding this natural phenomenon which is very different from previous models, but utterly natural. It’s a modern theme of physics to study things by looking at their singularities – to think about them geometrically.”
In order to test their theory, co-author Raymond Lee took four different polarized photographs of each of two clear-sky cases at the United States Naval Academy in Annapolis, Maryland, using a Nikon digital camera with a specially converted fisheye lens. When they compared these detailed observations to the pattern predicted by their model, they found that the fit was very good, indicating that the arrangement of the singularities could be vital in shaping the overall “fingerprint in the sky”.
Many scientists and mathematicians believe that simple, concise explanations of natural phenomena are better or closer to some underlying truth than more complex ones. Professor Marcus du Sautoy, from the Mathematical Institute at the University of Oxford, said: “Having a sense of beauty and aesthetics is an important part of being a scientist. Nature seems to be a believer in Occams Razor: given a choice between something messy or a beautiful solution, Nature invariably goes for beauty.
"This is why those scientists with an eye for aesthetics are often better equipped for discovering the way Nature works. We might find a complicated ugly solution but that is probably a sign that we havent yet found the best explanation. The fact that there is so much beauty at the heart of Nature is what gives scientists a constant sense of wonder and excitement about their subject.”
David Reid | alfa
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
Larsen C Ice Shelf rift finally breaks through
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...