Causality in curved space

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Fizik Bölümü, Türkiye

Tezin Onay Tarihi: 2018

Öğrenci: BASSEM ALJASEM ALASHOUR

Danışman: BAYRAM TEKİN

Özet:

The notion of Causality is a key concept in formulating theories that describe real physical systems. So when a proposed model violates this concept this usually signals the existence of an error in the conceptual formulation or in the physical understanding of the results, which might indicate to us which models should we pursue, modify or drop all together. In this work the possibility of causality violations introduced by modifying Einstein gravity is studied using the idea of the time-delay introduced to a particle while crossing the shock-wave generated by another particle, known as Shapiro-like time delay. We will see that some of the apparent causality violations are just a mathematical artifact of our formulations. While in other cases these violations can be lifted off if the theory is embedded in another theory with a better behaved UV completion. Is it also noticed that when we study local causality in (2+1) General Relativity the notions of causality and unitarity are compatible with each other.