The total energy of the universe appears to be 0. Let us assume it is 0. Then to observe the universal wavefunction, I can only observe that which I'm not a part of so I take my mass out of the mass of the universe. The effective observable universe for me now has the mass (0-m) where I am 'm' kg. Now the time evolution of this wavefunction is seemingly dependent on my mass out of everything that could've been. Therefore different observers will observe different universes.