Applicability of Maths to the Universe

[GrandizerII]

Imagine, for example, a very large prime number which no one has discovered.

Of course, the cardinality of the set of prime numbers is a countably infinite set.  Thousands of mathematical proofs exist that prove such; of course, an acceptance of ZFC and the Axiom of Infinity is necessary to get the balling rolling, so to speak.  Professor Wes Morriston has written extensively in response to WLC, and even quotes Craig who once stated that his ideas will make sense to an individual at least until that person has taken a course in elementary number theory, complex analysis, etc.

I keep hearing about this ZFC stuff but never getting around to reading up on it. ELI5 (or perhaps ELI15): What's it about?

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That said, let me share with you how I intuit numbers like 2. Based on how I currently see things, there is no number 2 floating out there in the Platonic sense and serving as some form of cause for the concept of 2 in our minds. For me, number 2 strictly exists in our minds, as a way to "visualize" a certain quantity of identical things. The quantity is out there in a "vague" sense, but it is not decipherable as "2" without a mind to see separateness and "identicalness" of the objects of interest. What would be the biggest challenge to this view?

This is all very difficult for me. As so often on this forum, I find myself in the role not of advocating a position but of wanting others to hold back from a position about which they may have too much confidence.

It's called revelation!

One thing to ponder: numbers which no human has ever thought of yet. Imagine, for example, a very large prime number which no one has discovered. It has never appeared in the mind of any person. If numbers depend for their existence on appearing in minds, then this number doesn't exist. But even so, it may be more proper to say that it does exist, but hasn't been discovered yet. If it does exist, but has never been thought, then "where" is it?

Yes, it does seem like even numbers that no human being has ever specifically thought of still nevertheless have to exist, but I think that's by nature of being part of the number system which does exist in our minds. That's my first impulse thinking about this question just now.

The example Popper uses is about symphonies, which are also World Three objects in his system, like numbers. Imagine Beethoven's 5th symphony. The symphony itself is not identical with its score or its CD. Those are recordings made of it, but are not the symphony itself. It somehow continues to exist whether anyone is hearing it or not.

I can't say I disagree here. It does seem like abstract objects somehow persist in existence in some unfamiliar way. But I do suspect the [start of] existence of such objects still remains contingent on people's conceptions of them.

But even conceding that, how would you link what you've said here to the original intended topic of this discussion? What does the nature of the existence of numbers suggest regarding the link between mathematics and the physical that challenges the materialistic pov?