"Is absolute zero cold enough?"*

Not saying that I have a complete understanding of what they accomplished, but absolute zero is the point at which all motion ceases. You can't, by definition, get a lower temperature than that.
What they DID do was induce a state where entropy and energy ducked behind the woodshed and... ah, I don't want to complete that metaphor.

: I encourage sci-fi stories, especially when we're dealing with advanced races
: such as the Forerunners and Precursors, to continue their "that can't
: happen" ideals, because otherwise why add "fiction" at the
: end of the science?

Because the events are fictional, even if the science isn't. = )

: Having this mindset, seeing advanced fictional races operate
: with "hard light" technology, floating colossal sized
: structures, and playing with evolution becomes such a ride because it's a
: constant "But, how? That's not possible!"

I like that too. But there's a line between science that is 'beyond our understanding', and the casual contempt for science and engineering that Star Trek and it's ilk revel in. I'm going to give this more thought, and then type up an article about it.

*And down in the valley, warm and clean
The little ones sit by their TV screen.
No thoughts to think, no tears to cry.
All sucked dry, down to the very last breath.