As a beginner physics student, I once entered the physics lab in a thrill of anticipation. I was about to reproduce defining experiments in physics, week after week.

The very first assignment was about … diffraction patterns! In a tiny, dimmed room I set up a laser or a Sodium-vapor lamp, diffraction gratings, and projection optics. The task was to measure the positions of the diffracted images of the slits of the diffraction grating, using a ruler projected onto the plane where the diffraction patterns emerged. They were better in line with the results of theoretical calculations! I recall vividly that we were warned that it would be futile to fake results: We had to provide realistic error bars, explain how errors would propagate through different steps of the calculation, and we would not be able to fake noise realistically!

This is a straight-forward exercise: it is very well-known physics. You need to keep track of numbers – back then, with pen and paper. But I do remember how exciting it was to see those feeble little stripes in the dark. Finally, I was doing physics – with professional equipment! That fascination of light in a dark lab never left me, and I specialized in laser physics for a few years! I still see the delicate green and cyan hues of colors of Argon ion laser beams, illumination dancing particles of dust.