You wouldn't be able to express BB(100) explicitly. My article is about a lower bound on the much smaller BB(63), and it's already very hard to give a sense of how large that is. Go would of course be able to give you the 100 bit program for it.
> Chaitlin's number is 1/2
We know that Chaitin's number is not computable. So it cannot be 1/2. It has an infinite binary expansion of which we can only ever compute a fixed number of bits.
> I guess by the definition, it is computable
It's not.
> I'm also struggling with the reciprocal of BB(100). This is rational, so maybe it too is computable.
A number x is computable if-and-only-if its reciprocal is. Any fixed integer, like N=BB(100) is computable (with the trivial program print N), and therefore so is its reciprocal. What is not computable is the function BB(.)
> there exists an algorithm to do X
What is X ?
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