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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vizualizace černoděrových prostoročasů / Visualization of black hole spacetimes

Maixner, Michal January 2018 (has links)
This work is focused on visualisation of Schwarzschild, Reissner- Nordström and Kerr black hole. The two-dimensional conformal diagram was constructed. In the case of Kerr black hole, the causal structure was visualized by intersection of chronological future of given point in spacetime with hyper- surfaces of constant value of Boyer-Lindquist coordinate t. Conformal diagram for Kerr black hole was constructed only in the neighbourhood of outer event horizon. Then the causal diagram, which is analogous to conformal diagram for Reissner-Nordström black hole was constructed. In all cases two-dimensional spa- celike hypersurfaces were chosen that were embedded into Euclidean space. The interpretation of time evolution of black hole universe was given to a sequence of such embedded hypersurfaces. In the case of Kerr black hole the embedding of outer ergosphere and outer event horizon were also constructed. 1
2

On curvature and Hawking radiation

Chernichenko, Alexsey January 2022 (has links)
Hawking radiation is a phenomenon where the combination of geometry of spacetime around a black hole and quantum effects near its event horizon causes particle emission. Stephen Hawking was one of the first to make computations and conclude that this is valid for every black hole in general. Therefore, the goal of the project was to understand how the presence of a black hole changes geometry of spacetime, explore some of its peculiar properties and, finally, connect it to Hawking radiation. It turns out that one way to describe geometry around a black hole is to use the Schwarzchild metric which fully describes surroundings of a non-rotating and uncharged black hole. Using the so called Klein-Gordon equation and some additional computations one then sees that there’s indeed a particle emission. However, the radiation appears to be observer dependent which is due to curvature near event horizon. Hawking radiation has temperature which happens to be extremely small to detect, but this result reveals the fact that black holes radiate faster as they shrink. However, the time it takes for an arbitrary black hole to evaporate is much longer than the age of the Universe. Encountering those and some other challenges Hawking radiation remains hypothetical. / Hawkingstrålning är ett fenomen där kombinationen av geometri av rumtid runt ett svart hål och kvantmekaniska effekter nära dess händelsehorisont leder till partikel emission. Stephen Hawking var bland de första att göra beräkningar och dra slutsatsen att detta är giltigt för alla svarta hål. Syftet med projektet var därför att förstå hur närvaron av ett svart hål ändrar geometri av rumtid, undersöka dess vissa speciella egenskaper samt anknyta det till Hawkingstrålning. Det visar sig att ett sätt att beskriva geometri kring ett svart hål är att använda Schwarzchild metriken som helt beskriver omgivningen av ett icke roterande och oladdat svart hål .Använder man sig av så kallade Klein-Gordon ekvationen och några ytterligare beräkningar så kommer man till slutsaten att det verkligen finns enemission av partiklar. Emissionen verkar dock vara observatörsberoende på grund av krökning nära händelsehorisont. Hawkingstrålning har temperatur som visar sig vara extremt liten för att upptäcka, men resultaten avslöjar faktumet att svarta hål strålar ut snabbare då de krymper. Tiden det tar för ett godtyckligt svart hål att koka bort är dock mycket längre än åldern of Universum. På grund av dessa och några andra utmanningar återstår Hawkingstrålning hypotetiskt.

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