Bayan haka, sai a amsa tambaya a baya a cikin wannan harshe kamar yadda aka wuce: Passage: Planck (1906a) ya bayyana mahimmancin mahimmanci kuma ya ba da dabi'u masu kyau don tsayin daka da ƙetare ta hanyar gyara kuskuren kuskure na kalmar da Einstein ya ba a 1905. Maganganun Planck sun kasance daidai da waɗanda Lorentz ya yi amfani da su a 1899. Bisa ga aikin Planck, Gilbert Newton Lewis da Richard C. Tolman (1908, 1909) sun haɓaka ma'anar mahimmanci ta hanyar bayyana ma'auni a matsayin rabo na motsi zuwa gudun. Saboda haka tsohuwar ma'anar ma'anar tsayin daka da ƙetare, wanda aka bayyana a matsayin rabo na ƙarfin taro zuwa hanzari, ya zama maras muhimmanci. A ƙarshe, Tolman (1912) ya fassara ma'auni mai mahimmanci kawai a matsayin taro na jiki. Duk da haka, yawancin litattafan zamani a kan ka'idar dangantaka ba su amfani da ma'anar mahimmanci ba, kuma ana la'akari da shi a matsayin mai yawa na musamman Tambaya: Menene ya zama ba dole ba?
tsohuwar ma'anar tsayin daka da tsayin daka