Masu sha'awa (amateurs) har yanzu suna goge madubin na'urar hangen nesa (telescope) da hannu. Suna goga faifan gilashi biyu tare da ƙasa mai goge (grit) a tsakaninsu. Bugun hannun ba su da tsari, barkatai ne. Duk da haka fuskokin biyu suna ƙarewa a matsayin siffofin ƙwallo masu dacewa da juna, daidai har zuwa 'yan gommai na nanomita.
Wani bincike na kimiyyar lissafi a SLAC da Stanford ya bayyana dalilin, yana farawa daga wata doka ta kankarewa (wear) ta 1927. Gilashi yana kankarewa da sauri a inda aka fi danna shi da ƙarfi kuma aka fi goga shi da sauri.
Bugun hannun suna nufar kowace hanya. Shimfiɗaɗɗun fuskoki (planes) da siffofin ƙwallo ne kaɗai ke tsira daga wannan daidaito (symmetry). Ƙananan kumburi suna ɓacewa cikin kusan awa ɗaya. Manya kuwa suna bazuwa kuma suna daidaituwa, a hankali kusan ninki 30.
Nauyi (gravity) yana kawar da shimfiɗaɗɗiyar fuska: faifan sama yana zurfafa, na ƙasa yana kumbura. Lissafi iri ɗaya yana bayyana duwatsun da ake juyawa a na'ura (tumbled pebbles). Suna yin sheƙi cikin makonni, amma za su buƙaci shekaru kafin su zama siffar ƙwallo.
Tushe: From Rock Tumbling to Telescope Mirror Grinding: How Optical Perfection Emerges from Random Motion, https://arxiv.org/abs/2611.01673










