There is a question that may be briefly stated as below: If time travelling is possible in DC universe then why it was not attemted to save multitudes of Kryptonians by going back in time, before the distruction of Krypton. But DC never tried to bring the posative answer to this question. A POSSIBLE SUGGESTION It may be answered that not only Krypton was destroyed but with the distruction of Krypton the Time was also destroyed in relation to Krypton and there is no past of Krypton to which one may trevell by any time treveling machine or divice. But this answer may be a powerful answer yet it is hardly and scarly valid in DC Multiverse. How ever one may still attempt to make modifications in this theory to make it valid in DC MULTIVERSE.