Q&A: Chemistry
Chemistry
Question
Rabbi, in Berakhot 25b Rav Yosef says that there is a difference regarding the amount of water that must be added to a vessel so that one may cover it and recite the Shema. The difference depends on whether there was urine there first, or whether there was water first and then the urine was added. Is that also scientifically correct?
Answer
I didn’t understand the question. There is no factual claim here that science is supposed to determine. This is a halakhic question of what nullifies what, and how.
Incidentally, this is not about covering oneself with the vessel (that is an earlier passage there). Here the issue is reciting the Shema when there is a vessel containing urine in front of him, and adding water nullifies the urine and makes it possible to recite the Shema facing it.