Assume the universe exists. Then everything in it can be put into a set U such that U contains, by definition of U, everything in the universe and nothing else. Since U already contains everything in the universe, no set contains more elements in the universe than U. But by Cantor’s Theorem, the powerset of any set S always contains more elements than S. So, the powerset of U contains more elements than U. But each element of the powerset of U forms a part of the universe and is thus also in the universe. Thus, the powerset of U contains more elements in the universe than U. This is a contradiction. Therefore by proof by contradiction, our assumption that the universe exists must be false. Therefore, the universe does not exist.

God I wish this was understood more widely.
I swear the confidence with which people rule out things via deduction truly astounds me. It’s as if the history of science hadn’t already humbled such enterprises.

“But each element of the powerset of U forms a part of the universe and is thus also in the universe.”

…BZZZZZT… Incorrect assertion.

A “powerset” contains both the empty (non-existent) element as well as that entire set as an element.
Neither of those are “part of the universe”.
The empty set is by definition not a part of the universe.
And the entirety is not a “part of”.

All elements of a set exist. Your claim that the powerset of a set can contain elements that don’t actually exist doesn’t seem correct. An element of a set that does not exist seems to be an element that is not part of the set.

Oh my. Sets are not real, nor are their members. Let’s say i have five real apples - apples that I could eat. The set “Five Apples” does not exist empirically - even though the apples themselves do. And each “element” or member of the set - they don’t exist empirically, either - as members of a set, even if they exist empirically. Sets and their members are abstractions.

This is just incorrect. They do not exist in the same way that we take the Universe of the stuff in it exists - they do not exist empirically. Sets are abstractions. It’s mathematics. We can all think of sets whose members do not exist empirically. Empirical existence is not required for set membership.

I choose a set that contains all things that exist and all things that do not exist. My set exists merely because I chose it and defined it. But now I have a set within the universe that contains more elements in it than the universe contains, yet is within the universe as an element of what exists. The small portion of the whole, the set, is greater than the whole.

First of all, what are we doing here? - the process, I mean: “Put into” what? “Set U?” What is that, exactly? What are we putting into what here? Where are we “putting” it? Seems to me we’re just renaming shit for the sake of renaming it. Correct me if I’m wrong.

Second, there’s no need for the assumption. The universe exists. That’s exactly what it does. In fact, I would argue “existence” and “the universe” are synonymous to begin with (also Dasein, Being with a capital B, and so on), but maybe that’s just me.

Well, if I’m following you, “U” is here already deemed synonymous with “the universe”: we’ve only “put-it-into-a-set” (whatever that means); so what we’re left with is: “The universe contains, by definition of the universe, everything in the the universe and nothing else.”

I mean … okay. Can’t say I disagree (lol).

Again, correct me if I’m wrong, but by the same token as above, this sentence says: “The universe contains everything in the universe, no ‘set’ contains more elements in the universe than the universe.”

Am I just an idiot, or is this redundant nonsense? (The former is totally possibile, no disrespect intended.)

I know dick about math or Cantor’s Theorem, but the bolded is nonsense.