As someone with a science and engineering background, I always find it kind of amusing that in the financial world, there's all this talk about 'liquidity'. One of those terms that doesn't really exist in the physical world at all. Nobody can really even define it much better than 'the amount of monetary units sloshing around' at any given time. π€·ββοΈ
I think more in terms of viscosity: the resistance to change in a liquid, or internal friction. That sends you down a fun rabbit hole of Newtonian and non-Newtonian fluids that behave differently based on external stressors. Bitcoin is kind of non-Newtonian in a sense, but it's not a perfect analogy.
The hilarious part is that if you google what liquidity is in scientific terms, all the top hits are economics sites that are quite confident that there's a definition in physics. I have yet to easily find one in a physics text. π