"Alas, no, I was not flirting, though you are terribly attractive."
"So. I'd whip up an actual physical demonstration of this but I don't know if it would work either - but, let us take it as read that the thing I'm about to try and explain is how a lot of universes work, including all the ones I've yet visited." Sure, that's n=2, but she's fairly confident this will continue to hold.
"Light. The mundane sort." She snaps one into existence. "Light is a very interesting thing. Because it can behave both like - grains of dust, bouncing around in water, and also like a ripple on the surface of that water - being probabilistically more likely to be somewhere where there is a peak, less likely where there is a trough - and this depends upon whether you're trying to pin it down or not.
"This is proveable by something called the double-slit experiment."
She sets up the image of one.
"The double-slit experiment is relatively simple.
"On one side of a set of, you guessed it, two vertical slits, you have a source of - singular quanta of light, photons. On the other, you have a detection medium.
"You release one photon.
"The detection medium," and here she actually does animate the process somewhat, "measures two impacts. The singular photon passed through both slits."
"They spread out into a recognizeable pattern if you do a lot of that, but I'm not that invested in particle physics.
"Now. You put detectors in the slits, as well as on the other side. And that changes what happens.
"The photon will only pass through one of the slits if they're set up that way."
She demonstrates, again.
"On a human scale, this is pretty much entirely negligible. But it's the same shape of thing as I was trying to do, sort of.
"I was attempting to establish... the possibility of me-investigating-the-spell and me-not-investigating-the-spell as two separate probabilities of existence - such that I could later collapse them back to one truer reality in my favor. There's a bunch more in there I've elided, like how there is a fundamental uncertainty in measurement of particles and that also involves wavefunctions, and how, well, technically the thing I'm doing - or trying to do, at least - is based on a misunderstanding of all the underlying physics, but that's the gist of it.
"Of course, it's Void magic, so if I can imagine it anyway, it works. Void is such bullshit when you have a multiverse to steal the good ideas from. But I digress."