Science can only investigate physical processes. But this will tell us nothing about how or why those processes are occurring, and not some other processes, or no processes at all. So when science discovers a process, this does not in any way detract from the mystery source of all the processes Make up what we experience as existence. Science is not eliminating God, or the necessity for an existential source and purpose for all that exists. If you can't wrap your head around this, it's not my fault.
I don’t know why you think there’s something there for me to wrap my head around. You’re speaking in random platitudes, and mixing terms in a way that indicates you don’t understand what you mean yourself.
Of course science doesn’t address purpose - that is a given. This idea of a ‘mystery source’ is just a mash-up of something you haven’t properly understood.
If you are referencing existentialism (although it seems more likely you are just bandying about terms you don’t know the meaning of) the majority of existentialist philosophy, after Kierkegaard in any case, denies any kind of purpose or meaning ‘for all that exists’. There is no logical necessity for purpose, that idea is simply absurd.
It’s far better to simply admit you don’t know what you are talking about - that opens up the possibility of learning - than to spout meaningless tripe.