The Time Machine Factory [unspeakable, speakable] on Time Travel -TM2019

Session

Faster Than Light - SpaceTime Navigation

Session V

9 Oct 2019, 14:10

Turin

26. Dirac tunneling: superluminal velocities and closed time-like curves?

Prof. Randall Dumont (McMaster University, Hamilton, Ont., Canada)

09/10/2019, 14:10

talk

The Hartman effect – first discovered by MacColl, in 1932 – is the claimed observation that, when a particle tunnels, it arrives at the opposite side of the barrier the moment it encounters the barrier. If this is so, then sufficiently wide barriers and fast particles should produce superluminal effective velocities. However, such superluminal effective velocities have been dismissed as...

36. Preemptive chronology protection and superluminal travel.

Prof. Stefano Liberati (SISSA)

09/10/2019, 14:55

talk

In this talk I shall review the implications of superluminal travel and the means by which it can be achieved in classical General Relativity. We shall then see in the specific case of superluminal warp drives how it seems that a preemptive form of chronological protection is at work once their dynamics it is analysed within quantum field theory in curved spacetime. Finally, we shall discuss...

13. Causal set theory and quantum fields

Dr Marco Letizia (University of Waterloo and Perimeter Institute)

09/10/2019, 15:40

talk

In this talk I will discuss the properties of quantum fields in causal set theory, a theory of quantum gravity in which nonlocality emerges as a consequence of discreteness and local Lorentz invariance. In particular I will present some recent results regarding the computation of entanglement entropy in this context and consider some comparisons with other models of quantum spacetime with...

7. Remote time manipulation

Dr David Trillo (IQOQI-Vienna)

09/10/2019, 16:30

talk

Harnessing the flow of proper time of arbitrary external systems over which we exert little or no control has been a recurring theme in both science and science-fiction. Unfortunately, all relativistic schemes to achieve this effect beyond mere time dilation are utterly unrealistic. In this work, we find that there exist non-relativistic scattering experiments which, if successful, freeze out,...

16. Quantum field measurements without superluminal signalling

Dr Jason Pye (University of Waterloo)

09/10/2019, 16:50

talk

Although quantum field theory inherits much of the basic structure laid out by the postulates of ordinary quantum mechanics, it is known that the measurement theory cannot go through unscathed. There are examples of idealised measurements in quantum field theory which produce superluminal signalling. These examples indicate that endowing quantum theory with a relativistic spacetime structure...

53. New Classes of Warp Drive Solutions in General Relativity

Dr Alexey Bobrick

09/10/2019, 17:10

talk

We report on the results of our ongoing work on reducing the energy requirements of classical warp drives. The existing warp drive solutions by van den Broek and Alcubierre assume spherical symmetry. We show that by considering their counterparts of arbitrary shape, one can reduce the energy requirements by orders of magnitude. Further, I will outline a method of constructing more general...

6. Traversable Casimir Wormholes

Remo Garattini (Università degli Studi di Bergamo)

10/10/2019, 09:00

talk

Traversable Wormholes are a prediction of General Relativity. After the discovery of the Gravitational Wave signals detected in 2015, Traversable Wormholes have had another renaissance, because they can be considered as Black Hole Mimickers.
In this talk we give a pedagogical introduction and we present some theoretical aspects at classical and semiclassical level, namely when the source has...

19. Dynamical wormholes in Robinson-Trautman class

Dr Otakar Svitek

10/10/2019, 09:45

talk

We present wormholes based on the Robinson–Trautman class of spacetimes generally containing geometries without symmetries. We focus on a model sourced by a ghost scalar field investigating its asymptotics, stability and other issues. Within the same family of geometries one can construct a thin-shell model which approaches simple spherically symmetric wormhole in the distant future. The...

3. Sound Propagation in the Ellis Wormhole

Prof. Zaza Osmanov (Free University of Tbilisi)

10/10/2019, 10:05

talk

For the simplest case of Ellis Wormhole (WH) the fluid moving through the mentioned metrics is considered. For this purpose, the set of linearized equations composed of the Euler and continuity equations is examined. The propagation of sound waves has been considered and corresponding non-trivial analytical and numerical results – obtained.