Cosmological Horizons and the Unruh Effect

Sammanfattning: The black hole information paradox, which states that the evaporation of black holes due to Hawking radiation results in a violation of the conservation of quantum information, is arguably one of the most fundamental problems in all of modern physics. Through the equivalence principle, the essence of the problem can be understood and studied in the context of much simpler flat spacetime (described by the theory of special relativity); in this context the Hawking radiation takes the form of the so-called Unruh effect, a thermal effect in the vacuum of a Minkowski quantum field theory that can be measured by accelerated observers. In this essay, the Unruh effect is reviewed and derived from the first principles of special relativity and quantum field theory -- we emphasize the importance of horizon effects in this derivation. Moreover, its connection with black hole physics and applications to the information paradox is discussed and explored in the context of cosmological horizons.