It confounds everything she's ever thought she knew and understood about quantum physics. It coaxes her into contradictions and impossibilities, forcing her to reject the absolutes of mathematics and accept irrationality as a basic foundation. It dances along time and space, both a wave and a particle, laughing at her specialized knowledge and mocking the cool logic of numbers.

And she loves it. Because it also introduces her to wonders, both beautiful and terrible, that she never dreamed existed. It challenges her to think outside the box, and then discard the box entirely and build a brand new one. It teaches her to step sideways in space-time through blue-shifted light into infinite potential, to abandon the stolidity of human thought and open her mind to a galaxy of questions and theories and sometimes, even answers.

She knows that she's paid the price: in grief, and pain, and mental scars; in love, and loss, and a deeper, starker glimpse at the depths of her own psyche than anyone would ever want to see. But it's a price she's paid willingly, and she'll continue to pay, as long as that siren song beckons her to step into wonder and enchantment.

It's ten years, now, that she's been walking through the Gate.

And no matter how blasé she might appear on the outside, no matter how casual her routine habits seem, Sam knows that it will never, ever get old.