unprovably
/ʌnˈprɒvəbli/Definitions
1. adverb
in a way that cannot be proven or disproven, especially because the truth of the statement is assumed or is not the point.
“The philosopher’s ideas were unprovably fascinating, and many people were drawn to them.”
2. adverb
to a degree that cannot be proven or disproven.
“The new technology is unprovably faster than the old one.”