0! = 1 isn’t an exception.
Factorial is one of the solutions of the recurrence relationship f(x+1) = x * f(x). If one states that f(1) = 1, then it only follows from the recurrence that f(0) = 1 too, and in fact f(x) is undefined for negative integers, as it is with any function that has the property.
It would be more of an exception to say f(0) != 1, since it explicitly denies the rule, and instead would need some special case so that its defined in 0.
Who did ever say that? Not a single article that I’ve read about Terryology has praised it. I guess the Joe Rogan podcast helped it gather some followers?
Multiplication order in current mathematics standards should happen the other way around when it’s in a non-commutative algebra.
The good thing about multiplication being commutative and associative is that you can think about it either way (e.g. 3x2 can be thought of as "add two three times). The “benefit” of carrying this idea to higher-order operations is that they become left-associative (meaning they can be evaluated from left to right), which is slightly more intuitive. For instance in lambda calculus, a sequence of church numerals n1 n2 … nK mean nK ^ nK-1 ^ … ^ n1 in traditional notation.
For example, we can’t write 2ω for the next transfinite ordinal because 2ω is just ω again on account of transfinite and backwards multiplication weirdness, and we have to write ω·2 or ω×2 instead like we’re back at primary school.
I’d say the deeper issue with ordinal arithmetic is that Knuth’s up-arrow notation with its recursive definition becomes useless to define ordinals bigger than ε0, because something like ω^(ω^^ω) = ωε0 = ε0. I don’t understand the exact notion deeply yet, but I suspect there’s some guilt in the fact that hyperoperations are fundamentally right-associative.
They are still real numbers. Specifically uncomputable, normal numbers. Which means their rational expansion contain every natural number.
Zero is the absence of a quantity, but it is still a number.
It gets deeper. It’s also the same as the 0-k-vector, the 0-k-blade, the 0-multivector, the only number that is its own square besides 1, etc…