Well, it turns out that Einstein and Kaluza and many others worked on trying to refine this framework and apply it to the physics of the universe as was understood at the time, and, in detail, it didn't work.
Kā izrādās, Einšteins, Kaluca un daudzi citi centās pielāgot šo priekšstatu un piemērot to Visuma fizikai, kas kā jau tajā laikā bija zināms, arī sīkumos, neizdevās.