yesterday is gone
irrevisable
irrevisability
unalterable
inalterable
what's done is done
that's the way life is
inflexible
les jeux sont faits
incorrigible
the damage is done
you can't step in the same river twice
the fox may grow grey but never good
irreparable
the wolf may lose his teeth but never his nature
water over the dam
unrevisable
unmarriageable
unalterably
inexorable
irreversible
settled
unchangeable
a leopard cannot change its spots
you can't teach an old dog new tricks
ungainsayable
culminate
static
unrebuffable
inconvertible
untransmutable
immutable
unreformable
you can't unring a bell
unpremeditable
ununifiable
unupgradable
rearrange the deck chairs on the Titanic
noncontinuity
nonreversible
time will tell
unregainable
you can't put the toothpaste back in the tube
irrepealable
irrevocable
unrepentable
unrestorable
unstanchable
Novikov self-consistency principle
unbending