Einstein's theory is not absolutely correct; it is simply far better than any other theory we currently have, our best current approximation of reality. However, it could be proven wrong at any time. Science, by its nature, is inherently agnostic.
Hell Fast·
可区分性
If you can't distinguish two things, or to some point two things are not distinguishable, simply consider they are the same is a practical way to solve your problems.
Indistinguishability is just unreasonable sophistry