November 29, 2023

Scratches around the sun - a spectrum of science

Scratches around the sun – a spectrum of science

Amazing physics hides behind many everyday objects. I felt for many years Hans Joachim Schlichting He discusses these phenomena and explains them in his column for readers of the “Scientific Spectrum”. Schlichting is Professor of Educational Physics and worked at the University of Münster until his retirement.

Although the shiny areas give an impression of how bad the car’s paint has been in everyday life, you should keep in mind that the actual number and length of small scratches is much greater. A computer simulation illustrates this: to randomize various invisible dents in diffused light, you can visualize the sections appearing to light with a point light source placed on top of them vertically. The reflections then draw a pattern similar to that on the car’s roof yet reflect only a small portion of all the bumps.

© H. Joachim Schlichting (Detail)

Typical Quirks | A simple computer simulation shows only a few sections of normally undetectable bumps (left) under a point light source (right).

These radioactive rings can also be seen, for example, as reflections on cutlery and other opaque objects, but also when looking through the plastic windows of an airplane. These are also subject to mechanical influences. You can only see some small traces if you look through the window at the light source. In this case, the bright sections are not grouped around the mirror image, but around the original light source. Therefore, the physical conditions differ in that light is not reflected on scratches, but rather is refracted by them.

© H. Joachim Schlichting (Detail)

Knife Reflections | Under the light source, microscopic bumps on frequently used objects such as a spoon produce ring structures.

If you take a closer look, many grooves shimmer with color. Apparently, some of the minute irregularities are in the order of the wavelength of light. Then diffraction occurs, which divides the incident white light into the components of its spectrum. The structures act like tiny slits along which the front of the incident radiation emits elementary waves in all possible directions.

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If they are interfered with in the eye or on the camera chip, certain wavelengths are amplified or attenuated according to the relevant path differences. Depending on the position of the watch, dents often shimmer so intensely that they appear much wider than they really are.