Please dwell on this question of yours.
If you meditate on it, it can give you a lot for your research.
Because this question of yours arises from a fundamental misunderstanding.
Concerning existing, demonstrating and absolute.
Your question can only be answered with no. Absolute Truth cannot be proven.
But what you should ask yourself is why.
You may then realize that Truth does not exist precisely because it is!
It is beyond existence.
And therefore nowhere.
How can it ever be proved that which allows each proof?
Your question should die before it is formulated.
And by dying the question you could then transcend.