In my opinion an objective truth about our universe can never be provable and thus it is irrelevant.
Consider this, we have an observer inside the universe O that is subject to the laws of the universe, which we will deem as a bias B. For any question X asked in the universe, in order for O to answer X, O must answer subject to the constraint of his bias in B, thus whether or not O's answer to X is true cannot be shown unless the bias B is unconstrained, or many such O exist such that all bias B are considered (in which it can be derived the answer to X). In our universe the bias B is a continuous set, it includes things such as location, informational bias, sensory bias, processing bias and for living sentient creatures things such as psychological bias and social bias, each bias is itself continuous and thus can contain an infinite amount of values, or at the very list a number of values so large that the laws of the universe actually prohibit any sensible quantity of things to occupy all different bias combinations. Because of this we say that the latter option (occupying all possible bias to answer any question X) is impossible. We also say that because we are contained within our universe, any question that is asked of us that describes our universe will inevitably, and certainly, exhibit a bias based on the universal laws. So thus we say the former (have B unconstrained) must also be impossible so long as we remain in our own universe.
SO thus, no answers can be truly known with certainty about anything. Lets talk about a few counter examples that most people like to come up with.
The first counter example is this, if nothing can be proven to be true, how can you prove that the statement "nothing is true" is true? The answer is you can't, my proof underlies an important assumption impossible to prove. The assumption that any bias B will augment an answer to any question X such that the answer to X after constrained by the bias B is different from the original answer of X. Whether this is true is unknown and I feel it is impossible to prove because in order to prove it, one requires knowing the original answer of X, which we've shown at least within this post is impossible. It creates a cyclic argument, which is expected from Godel's Incompleteness theorem which states that no complete model of the universe can ever be consistent and vice versa. Therefore, it is actually impossible to prove whether it's impossible to prove stuff! So possibly this theory is wrong but whether or not it is, is forever out of our grasp.
The second counter example is that of mathematical proofs. I have been very specific to say that it is impossible to prove any truth of our universe as we are constrained by the bias's of our universe. However, we create a brand new universe when we talk about mathematics, a universe with constraints and biases that do not apply to us, because they do not apply to us we don't follow the same rhetoric as in the case of a question about our universe. Basically in a nutshell, we invented mathematics with a series of rigorous assumptions, given that we are outside observers to mathematics and we have defined these assumptions (axioms) rigorously, then we can in fact prove with certainty mathematical truths about the mathematical world, while still never being able to prove with certainty truths of our own word.
So tl;dr:
We can't prove any truths of our universe, we can't even prove that we can't prove stuff.
