Conversations on the Plurality of Worlds in France and elsewhere, and was regularly published. In 1691, Fontenelle was elected to the Académie française. Conversations on the Plurality of Worlds Conversations on the Plurality of Worlds () is a popular science book by French author Bernard le Bovier de Fontenelle, published in 1686. It offered an explanation of the heliocentric model of the Universe, suggested by Nicolaus Copernicus in his 1543 work "De revolutionibus orbium coelestium". The book is Fontenelle's most famous work and is considered to be one of the first major works of the Age of Enlightenment. Unlike many scientific works of its time, "Conversations
Introduction to the mathematics of general relativity the gravitational field outside a spherical mass, on the assumption that the electric charge of the mass, the angular momentum of the mass, and the universal cosmological constant are all zero. The solution is a useful approximation for describing slowly rotating astronomical objects such as many stars and planets, including Earth and the Sun. The solution is named after Karl Schwarzschild, who first published the solution in 1916. According to Birkhoff's theorem, the Schwarzschild metric is the most general spherically symmetric, vacuum solution of the Einstein field equations. A Schwarzschild black hole or static black hole is a black hole