There is a minimum viscosity. You cannot make a fluid arbitrarily thin.

The floor is set by quantum mechanics — by ℏ and the electron and atom masses. Below it, momentum simply can't diffuse any faster.

The part that stops me: the same physics — a quantum floor on how fast momentum can move — governs a glass of water at room temperature and quark-gluon plasma at a trillion degrees. Fifteen orders of magnitude in temperature, one limit underneath.

And blood sits inside that window. Physicists argue that shifting ℏ a few percent would make it too thick or too thin to be alive.