27 citations · 114 across the 28 of their papers we have counts for
29 papers
Relative Entropy in de Sitter is a Noether Charge
Markus Fröb, Albert Much, Kyriakos Papadopoulos
We compute the relative entropy between the vacuum and a coherent state for a massive scalar field in de Sitter spacetime, using Tomita-Takesaki modular theory and the Araki-Uhlman…
Non-commutative Geometry from Perturbative Quantum Gravity in de Sitter spacetime
Markus Fröb, William C. C. Lima, Albert Much +1
We show that a non-commutative structure arises naturally from perturbative quantum gravity in a de Sitter background metric. Our work builds on recent advances in the construction…
Non-commutative coordinates from quantum gravity
Markus B. Fröb, Albert Much, Kyriakos Papadopoulos
Local observables in (perturbative) quantum gravity are notoriously hard to define, since the gauge symmetry of gravity -- diffeomorphisms -- moves points on the manifold. In parti…
Non-commutative Geometry from Perturbative Quantum Gravity
Markus Fröb, Albert Much, Kyriakos Papadopoulos
Trying to connect a fundamentally non-commutative spacetime with the conservative perturbative approach to quantum gravity, we are led to the natural question: are non-commutative…
Natural vs. Artificial Topologies on a Relativistic Spacetime
Kyriakos Papadopoulos
Consider a set equipped with a structure . We call a natural topology , on , the topology induced by . For example, a natural topology for a metric space $(X,…
On Global Hyperbolicity of Spacetimes: Topology Meets Functional Analysis
Felix Finster, Albert Much, Kyriakos Papadopoulos
This chapter is an up-to-date account of results on globally hyperbolic spacetimes, and serves several purposes. We begin with the exposition of results from a foundational level,…
On Completeness of the Alexandrov Topology on a Spacetime: remarks and some corrections
Kyriakos Papadopoulos, Nazli Kurt
We clarify and discuss a misunderstanding between uniform completeness and metric completeness, that has appeared in the literature in a study on the Alexandrov topology for a spac…
On a duality between time and space cones
Waleed Al-Qallaf, Kyriakos Papadopoulos
We give an exact mathematical construction of a spacelike order , which is dual to the standard chronological order in the -dimensional Minkowski space , and we di…
On null geodesically complete spacetimes uder NEC and NGC; is the Gao-Wald "time dilation" a topological effect?
Kyriakos Papadopoulos
We review a theorem of Gao-Wald on a kind of a gravitational "time delay" effect in null geodesically complete spacetimes under NEC and NGC, and we observe that it is not valid any…
On sliced spaces: Global Hyperbolicity revisited
Kyriakos Papadopoulos, Nazli Kurt, Basil K. Papadopoulos
We give a topological condition for a generic sliced space to be globally hyperbolic, without any hypothesis on the lapse function, shift function and spatial metric.
Are four dimensions enough, a note on ambient cosmology
Kyriakos Papadopoulos, Nazli Kurt, Basil K. Papadopoulos
The group of homothetic symmetries in the conformal infinity (the -dimensional "ambient boundary") of a -dimensional spacetime restricts the choice of topology to a topology…
On the Causal and Topological Structure of the -Dimensional Minkowski Space
Kyriakos Papadopoulos, Nazli Kurt, Basil K. Papadopoulos
A list of all possible causal relations in the -dimensional Minkowski space is exhausted, based on the duality between timelike and spacelike in this particular case, and th…
Spacetimes as topological spaces, and the need to take methods of general topology more seriously
Kyriakos Papadopoulos, Fabio Scardigli
Why is the manifold topology in a spacetime taken for granted? Why do we prefer to use Riemann open balls as basic-open sets, while there also exists a Lorentz metric? Which topolo…
On the Orderability Problem and the Interval Topology
Kyriakos Papadopoulos
The class of LOTS (linearly ordered topological spaces, i.e. spaces equipped with a topology generated by a linear order) contains many important spaces, like the set of real numbe…
Robots That Do Not Avoid Obstacles
Kyriakos Papadopoulos, Apostolos Syropoulos
The motion planning problem is a fundamental problem in robotics, so that every autonomous robot should be able to deal with it. A number of solutions have been proposed and a prob…
Nests, and their Role in the Orderability Problem
Kyriakos Papadopoulos
This chapter is divided into two parts. The first part is a survey of some recent results on nests and the orderability problem. The second part consists of results, partial result…
A study concerning splitting and jointly continuous topologies on
Dimitris Georgiou, Athanasios Megaritis, Kyriakos Papadopoulos +1
Let and be two fixed topological spaces and the set of all continuous maps from into . We construct and study topologies on that we call ${\cal F}_…
Spacetime Singularities vs. Topologies of Zeeman-Göbel Class
Kyriakos Papadopoulos, Basil K. Papadopoulos
In this article we first observe that the Path topology of Hawking, King and MacCarthy is an analogue, in curved spacetimes, of a topology that was suggested by Zeeman as an altern…
Admissible topologies on and
Dimitris Georgiou, Athanasios Megaritis, Kyriakos Papadopoulos
Let and be two given topological spaces, (respectively, ) the set of all open subsets of (respectively, ), and the set of all con…
On Properties of Nests: Some Answers and Questions
Kyriakos Papadopoulos
By considering nests on a given space, we explore order-theoretical and topological properties that are closely related to the structure of a nest. In particular, we see how subbas…
The Order on the Light Cone and its induced Topology
Kyriakos Papadopoulos, Santanu Acharjee, Basil K. Papadopoulos
In this article we first correct a recent misconception about a topology that was suggested by Zeeman as a possible alternative to his Fine topology. This misconception appeared wh…
On Two Topologies that were suggested by Zeeman
Kyriakos Papadopoulos, Basil K. Papadopoulos
The class of Zeeman topologies on spacetimes in the frame of relativity theory is considered to be of powerful intuitive justification, satisfying a sequence of properties with phy…
Helen of Troy, and the birth of Fuzzy Logic
Kyriakos Papadopoulos, P. Tseliou, B. K. Papadopoulos
The poem Helen of the Nobel laureate George Seferis was inspired by the anti war play Helen of Euripides. In his poem, Seferis empathizes with the hero of the tragedy, Teucer, who…
On the Possibility of Singularities on the Ambient Boundary
Kyriakos Papadopoulos
The order horismos induces the Zeeman topology, which is coarser than the Fine Zeeman Topology . The causal curves in a spacetime under are piecewise null. is consid…