Either might makes right, or something else makes right.

The former is mere force.  Whomever exercises it powerfully enough, is right.  They decide what is right and what is wrong, they decide the ruleset.

The latter is all other ethical theory - an appeal is made to something else outside the self, to which a comparison is made, and a judgement rendered as to how closely one conforms to that ruleset.

Mere force is bounded by space-time, by the four dimensions in which we exist.  Mere force is the pinnacle of space-time.

The latter ethical path, in order to trump the former, by necessity appeals to something outside space-time:  god(s) or inaliable rights or universal humanity.

Might makes right is the only ethical theory available to you if you think that space-time is all there is.