Actually, the title is a sensationalist lie designed to attract attention. I have no proof. Obviously. I'm not a mathematician. But if I did, it would go something like the following.
Step 1: Assume that there are ultimate laws of physics governing everything in the world. Say, the wave function of the Universe, whose knowledge allows one to know the Multiverse, as it was, is or will be. Or some other set of laws.
Step 2: Write these laws as a mathematically consistent formal system representing something akin to the Tegmark Level IV Ultimate ensemble.
Step 3: By Godel's incompleteness, there are some theorems in this formal system that cannot be proven.
Step 4: By construction, these theorems correspond to physical laws whose origins must forever remain a mystery to those inside the Multiverse, because they are a part of it.
Step 5: The consistency of our Multiverse can be proven in a formal system which describes physical laws of a larger world, in which our Multiverse is a small part of, essentially a simulation.
Step 6: Since we cannot determine the origins of our own physics, we cannot figure out a way to break out of our simulation.
On the bright side, there is a Corollary: Every level above us is also a simulation, so we are not alone!