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The epitome of acausal or anti-chronological behaviour would be to see a clock running backwards in time. In this essay we point out that this is indeed possible, but there is no problem with causality. What you see isnt what is really happening. Locally, causality is always respected. However our observation should be cause for pause to astronomers and cosmologists, who strictly observe events occurring at very large distances or very long ago and certainly not locally. It can be that what you see isnt what you necessarily get.
This talk discusses various aspects of the structure of space-time presenting mechanisms leading to the explanation of the rigidity of the manifold and to the emergence of time, i.e. of the Lorentzian signature. The proposed ingredient is the analog,
Relativistic quantum field theory in the presence of an external electric potential in a general curved space-time geometry is considered. The Fermi coordinates adapted to the time-like geodesic are utilized to describe the low-energy physics in the
The angular momentum of the Kerr singularity should not be larger than a threshold value so that it is enclosed by an event horizon: The Kerr singularity with the angular momentum exceeding the threshold value is naked. This fact suggests that if the
In this paper we consider a model for gravity in 4-dimensional space-time originally proposed by Chamseddine, which may be derived by dimensional reduction and truncation from a 5-dimensional Chern-Simons theory. Its topological origin makes it an in
Time stands still at a quantum critical point in the sense that correlation functions near to the critical point are approximately independent of frequency. In the case of a quantum liquid this would imply that classical hydrodynamics breaks down nea