This is the "Eighteenth Voyage" from the "Star Diaries" by Stanislaw Lem (which funny enough, is not included in every publication):
Ijon Tichy meets an astrophysicist named Solon, who spent his whole life studying the origin of the universe, coming to the conclusion that the universe indeed HADhad an origin in form of some primeval particle, but the tests also show that such particle couldn't exist. This leads him to believe, that one day universe would simply stop existing, because it shouldn't exist in the first place.
Ijon comes up with a solution: someone should shoot a single electron back in time to the moment before universe existed, thus giving it enough energy to create the Big Bang.
Project wentThe project was well under way and the new Universe was well designed, untilwhen Ijon got into arguean argument with the lab assistant named "Bunch" (Polish "Kupa"), who also wanted to be mentioned in the list of the "Creators of the Universe". Bunch and his mates (German Ast A. Roth and half Dutch, half British Boels E. Bubb) used a brief period when Ijon was away on holidays (and another lab assistant Serpentine had a date with a certain Eve) and putmade their own changes to the project, among them the fact that stars are now in "bunches", better known as galaxies.