If, due to space expansion, Earth observers are moving away from a light source faster than light speed, that light cannot reach Earth. Earth observers can see cosmic microwave background radiation, which was emitted 13.72 billion years ago and has redshift 1000 times. However, light sources 16 billion light-years away are expanding away at light speed, so that is the current maximum distance {horizon, cosmic} {cosmic horizon} from which light will eventually reach Earth. Because space expansion is exponentially increasing, in future cosmic horizon will decrease.
Physical Sciences>Astronomy>Universe>Cosmology
5-Astronomy-Universe-Cosmology
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Date Modified: 2022.0224