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How do we know that space expanded faster than a speed of light in inflation? Let us start from the beginning, on the reason that the Big Bang theory was proposed as a model for the universe. The reason was the observations that all clusters of galaxies were receding from each other. This is what happens from an explosion at the center, in three ...


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Inflation does not violate any local speed of light physics and there is no global prohibition in general relativity against spacetime points that are moving away from each other faster than the speed of light. Such spacetime points are simply not causally connected, i.e. there is no physical way to communicate between them (since light signals from one can ...


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The Big Bang was originally defined as the zero time limit of the FLRW metric, so it's a mathematical construct and not primarily something physical. We have chosen to apply it to the zero time limit of the universe because we thought the FLRW metric was a good description of the universe, but then inflation gatecrashed the party and spoiled the fun. So if ...


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In my opinion it all hinges on whether one includes quantization of gravity or not. The classical Big Bang just uses General Relativity and solutions of its equations. A singularity has a well defined meaning in the classical approach. As physicists are convinced that the underlying framework of nature is quantum mechanical it is expected that gravity ...


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In General Relativity, energy momentum flows from one region of spacetime to another. But there isn't necessarily a natural "total energy of the universe." It might help to contrast General Relativity with other theories. In Newtonian mechanics, a particle might gain kinetic energy while a corresponding gravitational potential energy decreases, thus you ...


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In Newtonian mechanics, a particle might gain kinetic energy while a corresponding gravitational potential energy decreases, thus you get that kind of conservation of energy. The total energy is the same before and after any event. However, the amount of energy depends on who's looking. In Special Relativity a transfer of energy has to happen at an event ...



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