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by maze-le
2840 days ago
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Because they are beginning to move faster than c, when these objects are at the very edge, due to the space between us and the edge expanding faster than c. This is called the cosmic horizon of the universe - sort of like an inside out event horizon of a black hole. A particle inside the horizon with a speed of c can still reach us (albeit very strongly redshifted), a particle outside the horizon would have to travel faster than c to reach us. The thing is, our own universe is still not old enough, that it can have a proper event horizon. It is estimeted, according to a model that assumes dark energy is a cosmological constant, that the universe must be at least 16GY old for a cosmic horizon to develop. Oh, and by the way, an expansion faster than the speed of light is consistent with relativity. Special relativity only describes local laws of physics -- you and the edge are not "local". And general relativity doesn't have a constraint on a maximum velocity between 2 arbitrary points in spacetime. |
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