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1

Oddziaływania czarnych dziur

Szybka Sebastian J.

Postępy Fizyki

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2023

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T. 74, z. 3

15--23

PL

Końcowym stadium niepohamowanego kolapsu grawitacyjnego jest pojedynczy obiekt zwany czarną dziurą. Czy czarne dziury zawsze mają taką samą uniwersalną postać? Chociaż twierdzenie o jednoznaczności czarnych dziur udziela pozytywnej odpowiedzi na to pytanie, to każde twierdzenie jest tylko tak silne, jak jego założenia. Przez wiele lat fizycy nie potrafili wykluczyć istnienia stacjonarnych konfiguracji dwóch czarnych dziur, które mogłyby wspólnie tworzyć bardziej złożony obiekt. Obecnie znamy rozwiązanie tego problemu.

EN

The final stage of an unrestrained gravitational collapse is a single object known as a black hole. Do black holes always have the same universal form? Although the uniqueness theorem provides a positive answer to this question, every theorem is only as strong as its assumptions. For many years physicists were unable to exclude the existence of stationary configurations of two black holes that could form together a more complex object. Currently, we know the solution to this problem.

2

Grawitacja widziana z Obserwatorium Astronomicznego Uniwersytetu Jagiellońskiego

Sokołowski Leszek M., Szybka Sebastian

Postępy Fizyki

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2023

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T. 74, z. 3

27--30

PL

W artykule omawiamy badania dotyczące zjawisk grawitacyjnych, które są prowadzone w Zakładzie Astrofizyki Relatywistycznej i Kosmologii, w Obserwatorium Astronomicznym Uniwersytetu Jagiellońskiego.

EN

In this article, we discuss research on gravitational phenomena being conducted at the Department of Relativistic Astrophysics and Cosmology in the Astronomical Observatory of the Jagiellonian University.

3

Close approaches of debris to LARES satellite during its first four years of operation

Paris C., Sindoni G., Sabato T.

Transactions on Environment and Electrical Engineering

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2017

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Vol. 2, No. 1

90--97

EN

Since its launch in February 2012, the LAser RElativity Satellite (LARES) of the Italian Space Agency experienced four close approaches with space debris. LARES orbits at an altitude of 1450 km, in a region where the density of space debris has a peak. However, the probability of an impact with a debris during the operational life of the satellite was reasonably low. The analysis of the close approaches identified three of the objects, that are from two peculiar population of objects. This paper discusses the problem of space debris in low orbit, the approaches occurred with LARES, and some possible scenarios related to space regulations and space law in case of an impact.

4

The ESA’S Scientific projects for Galileo Satellites 5 and 6 with eccentric orbits

Oszczak S.

Zeszyty Naukowe / Wyższa Szkoła Oficerska Sił Powietrznych

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2016

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Nr 4

125--134

EN

The experts of the ESA Galileo Scientific Advisory Committee (GSAC) have been involved in the analysis and technical discussions on the possibility of using Galileo Satellites 5 and 6 with eccentric orbits to support some Fundamental Physics experimentation, especially to perform a test of the gravitational redshift, a part of Einstein Equivalence Principle (EEP) General Relativity (specifically testing the LPI, Local Position Invariance). The gravitational redshift was performed with Gravity Probe-A (GP-A) in 1980 with the accuracy of 1.4 x 10-4. The analysis made by independent experts showed that using Galileo Satellite 5 data for one year (and if possible also Sat 6), in their final corrected orbits with an eccentricity of about 0.15, the accuracy could be improved by a factor of 5 and is optionally estimated to be even higher. Moreover, as noted by the involved experts, these tests are of high scientific relevance, as many alternative theories of gravitation predict violations of the Einstein Equivalence Principle at some level of the accuracy. The final recommendation of the GSAC provides the ESA with the possibility of establishing a scientific project activity, named as GREAT with two research groups (ZARM/SYRTE). The main objectives of this scientific project and expected results of gravitational redshift improvement are discussed.

5

The cauchy problem for the Einstein-Vlasov system

Mucha P. B.

Journal of Applied Analysis

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1998

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Vol. 4, nr 1

111-127

EN

We prove an existence and uniqueness for the Einstein-Vlasov system locally in time. Considerations are restricted to initial data which give a solution in harmonic coordinates.

6

The cauchy problem for the Einstein-Boltzmann system

Mucha P. B.

Journal of Applied Analysis

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1998

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Vol. 4, nr 1

129-141

EN

We prove an existence and uniqueness of solution for the Einstein-Boltzmann system locally in time. We restrict our attention to initial data which gives a solution in harmonic coordinates.