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Special relativity is restricted to the flat spacetime known as Minkowski space. As long as the universe can be modeled as a pseudo-Riemannian manifold , a Lorentz-invariant frame that abides by special relativity can be defined for a sufficiently small neighborhood of each point in this curved spacetime .
However, their effectiveness is limited by their small size and isolation from each other (which influence the maintenance of species), their restricted role in preventing climate change, invasive species, and pollution, their high costs, and their increasing conflict with human demands for nature's resources.
A Viking lander being prepared for dry heat sterilization – this remains the "gold standard" [1] of present-day planetary protection.. Planetary protection is a guiding principle in the design of an interplanetary mission, aiming to prevent biological contamination of both the target celestial body and the Earth in the case of sample-return missions.
General relativity explains the law of gravitation and its relation to the forces of nature. [2] It applies to the cosmological and astrophysical realm, including astronomy. [3] The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old theory of mechanics created primarily by Isaac Newton.
Strict nature reserves and wilderness areas are protected areas that are created and managed mainly for the purposes of research or for the protection of large, unspoiled areas of wilderness. Their primary purpose is the preservation of biodiversity and as essential reference areas for scientific work and environmental monitoring.
Nature reserves and wildlife refuges are areas of open space set aside for the sake of protecting non-human species. National parks , state parks , and municipal parks, recreation areas, and reservations are types of open space reserves managed by government agencies for the primary purpose of passive or active human enjoyment.
The best-known examples are black holes: if mass is compressed into a sufficiently compact region of space (as specified in the hoop conjecture, the relevant length scale is the Schwarzschild radius [156]), no light from inside can escape to the outside. Since no object can overtake a light pulse, all interior matter is imprisoned as well.
According to Mach, Newton's examples simply illustrate relative rotation of spheres and the bulk of the universe. [8] When, accordingly, we say that a body preserves unchanged its direction and velocity in space, our assertion is nothing more or less than an abbreviated reference to the entire universe. —Ernst Mach [9]