Radius of the observable universe is 46 billion light years. Say you have two civilizations 26 billion light years apart. Could they send maps of their observable universe to the other civilization so in 26 billion years they know what was beyond the edge of their observable universe?
In: Physics
In this specific case, no; universal expansion is too great at such distances. The universe is expanding at ~20km/s per million light years, meaning that two points 26 billion light years from each other would be moving apart from each other at approximately 520,000,000 m/s. Speed of light is just shy of 300,000,000 m/s.
The cosmic horizon is essentially constantly shrinking; with every moment the fraction of the universe that we will ever be able to interact with gets smaller and smaller as expansion continues.
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