1) regarding bloodletting, leeches are back in style.
2) a k’zayis is not “exact”. It’s a KEzayis, not a zayis.
3) If you don’t know science, you end up giving very poor answers when people raise questions, and you end up in many cases losing those people.
4) How much is pi in the gemarah?
Chazal, in the gemarah, were not “interested” in scientific experiments, so they used the science of their day when discussing things. It’s like 20 years ago, the atom was the smallest thing known to man, now we know there are things smaller. Doesn’t make anyone 20 years ago wrong, it just means we continuosly learn new things.