Supporting Einstein: Asymmetric Single-Slit Diffraction from a DIY Copper–Steel Slit

We report a simple DIY single-slit experiment that shows material-dependent asymmetry. A slit formed with copper on one edge and stainless steel on the other produces an asymmetric diffraction image. Flipping the same slit over causes the asymmetry to flip sides while the laser and screen remain fixed. This flip check is existence-level evidence that interaction occurs inside the slit and depends on the boundary materials, consistent with Einstein’s view. We avoid heavy analysis and provide photographs; not every attempt succeeded, but several clear examples were obtained.

Related: DIY report (DOI 10.5281/zenodo.17118246 )