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In 1992, Bañados, Teitelboim, and Zanelli discovered the BTZ black hole solution (Bañados, Teitelboim & Zanelli 1992).This came as a surprise, because when the cosmological constant is zero, a vacuum solution of (2+1)-dimensional gravity is necessarily flat (the Weyl tensor vanishes in three dimensions, while the Ricci tensor vanishes due to the Einstein field equations, so the full Riemann ...
The regions for finite v and r < 2GM is a different region from finite u and r < 2GM. The horizon r = 2GM and finite v (the black hole horizon) is different from that with r = 2GM and finite u (the white hole horizon) . The metric in Kruskal–Szekeres coordinates covers all of the extended Schwarzschild spacetime in a single coordinate system ...
In the spherical-coordinates example above, there are no cross-terms; the only nonzero metric tensor components are g rr = 1, g θθ = r 2 and g φφ = r 2 sin 2 θ. In his special theory of relativity, Albert Einstein showed that the distance ds between two spatial points is not constant, but depends on the motion of the observer.
Vacuum solutions are also distinct from the lambdavacuum solutions, where the only term in the stress–energy tensor is the cosmological constant term (and thus, the lambdavacuums can be taken as cosmological models). More generally, a vacuum region in a Lorentzian manifold is a region in which the Einstein tensor vanishes.
General relativity predicts that any object collapsing beyond a certain point (for stars this is the Schwarzschild radius) would form a black hole, inside which a singularity (covered by an event horizon) would be formed. [2] The Penrose–Hawking singularity theorems define a singularity to have geodesics that cannot be extended in a smooth ...
This is particularly true for low to moderate-intensity workouts (like going for a walk or doing gentle yoga), but even high-intensity routines are unlikely to cause a major sleep disruption if ...
Image credits: justin_agustin 2. Breathe Deeply. Deep, measured breathing is essential. Take a long, slow breath in, and exhale even more slowly. With each breath, consciously release any ...
He suggests pushing through the workout after a night of poor sleep sparingly—perhaps once per week—while prioritizing sleep on other days to allow your body to fully recover.