![The Time Machine Factory [unspeakable, speakable] on Time Travel - TMF2024](/event/751/logo-2372865151.png){kind=logo}
Conveners
Session II. Time travel and consistency
- Lorenzo Maccone
Session II. Time travel and consistency
- Seth Lloyd
It is well known that (static) regular black hole spacetimes can be sourced by appropriately chosen theories of non-linear electrodynamics. More recently, it was shown that many such models can also be obtained as solutions of vacuum gravity equations, upon considering an infinite series of quasi-topological higher curvature corrections. After reviewing both these approaches, I will show that...
The area of spatially stable marginally trapped surfaces (MTS) has a bound that depends on the minimum of a particular component of the Einstein tensor. I will prove that any spacetime containing spatially stable MTSs with area approaching the bound acquire universal properties generically. In particular, they possess marginally trapped tubes foliated by MTS of spherical topology, composed of...
We investigate a Schwarzschild metric exhibiting a signature change across the event horizon, which gives rise to what we term a Lorentzian-Euclidean black hole. The resulting geometry is regularized by employing the Hadamard partie finie technique, which allows us to prove that the metric represents a solution of vacuum Einstein equations. In this framework, we introduce the concept of...
In this talk I analyze the construction of quantum field theory in spacetimes that contain regions with closed timelike curves (CTCs). Additionally, I explore how particle detectors can discern the presence of CTCs in causally disconnected regions and differentiate between various spacetime topologies.
Before we can begin manufacturing time machines in our factory, we must consider whether those time machines could create time travel paradoxes, and if so, how these paradoxes might be resolved by existing or new laws of physics. We will first review the different types of time travel paradoxes and their proposed resolutions. Then we will present the results of our 3 recent papers...
The “problem of time” that approaches to quantum gravity have to either tackle or circumvent should, naturally, also occur in models of time travel trying to move beyond (semi-)classical gravity. From a viewpoint of canonical gravity a first hurdle to time travel is that the underlying quantization procedure relies on global hyperbolicity of the space-time to be quantized. As with any new...
I present a fully covariant framework for quantum mechanics, where the
quantization is based on quantum events instead of quantum systems. The
dynamics is introduced through constraints. Hopefully, this means that
the same framework can be extended also to general relativity (up to now
we developed only the special relativistic case), where it should
account for CTCs using the, previously...
Time is perhaps the most enigmatic concept in physics [1]. Indeed, we still lack an acceptable explanation for the observed preferred direction of time, and a universally-accepted quantum treatment of time as an observable [2 - 4]. The observations of discrete symmetry violations of charge conjugation (𝐶), parity inversion (𝑃), and time reversal (𝑇) observed in high energy particle decays,...
I review ideas regarding the possibility that black holes can become white holes through a quantum gravity process. Indeed, an observer passing through such a region of spacetime would effectively be travelling in the far future compared to an observer far from the effect, and vice versa should a white hole become black!
