Also a time machine (assuming there really isn't any fundamentally preferred frame of reference), and a bag of holding. Fig 5, page 19: https://arxiv.org/pdf/g

Also a time machine (assuming there really isn't any fundamentally preferred frame of reference), and a bag of holding. Fig 5, page 19: https://arxiv.org/pdf/gr-qc/0207057 https://arxiv.org/pdf/gr-qc/0207057 Put both together and call it a TARDIS.