A possible resolution to the Fermi Paradox is that we are living in an artificial universe, perhaps a form of virtualreality 'planetarium', designed to give us the illusion that the universe is empty. Quantum-physical and thermodynamic considerations inform estimates of the energy required to generate such simulations of varying sizes and quality. The perfect simulation of a world containing our present civilisation is within the scope of a Type K3 extraterrestrial culture. However the containment of a coherent human culture spanning ∼100 light years within a perfect simulation would exceed the capacities of any conceivable virtual-reality generator.