I would think the practical uses would be really small scale surprises. Like if you said “hey, I just discovered liquid crystals”, you probably wouldn’t be thinking they’d revolutionize televisions and displays, right?
I would imagine anything that pushed back when pushed would have interesting applications in setups with a “normal” liquid on one side of a flexible barrier and this new negative mass liquid on the other. It could potentially be like a self activating elastic system, I’d guess.
Like a shake weight that shakes itself, but probably only at tiny scales with a ton of energy put into the system right now. But who knows. Perpetual motion is always tantalizing, right?
Or a switch that has this on one side to make an imbalance on a tiny scale? We’ve gotten really good at making switches, but there’s always specialized needs and if it somehow outperformed silicon in some limited application, then it gets really interesting.
But right now, with two lasers holding a tiny bit for fractions of a second, it’s tough to make magic there.