In Italian popular culture, Friday the 17th (and not the 13th) is considered a day of bad luck. The origin of this belief could be traced in the writing of number 17, in Roman numerals: XVII. By shuffling the digits of the number one can easily get the word VIXI ("I have lived", implying death in the present), an omen of bad luck. In fact, in Italy, 13 is generally considered a lucky number. However, due to Americanization, young people consider Friday the 13th unlucky as well.
I think that is something like the question of why our universe is just as it is, because only in such a universe we can exist. If the universe were not so, we could not ask this question. If something would have happened, you could no longer post here!
And we might never see a nearly finished SpaceEngine.
Helped a group in an intro physics course perform a classic challenge of calculating the mass of a weight hung over a pulley by the acceleration it causes on a cart sliding on a track connected to it. The group's prediction was accurate to within 3%, and earned extra credit.
So it seems physics on Friday the 13th is no more than 3% different than physics on any other day. What a relief.