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From a physics standpoint, light crosses the entire universe in no time at all if you ignore our specific viewpoint. But relative to Earth, that same beam zips along at roughly 300,000 kilometers per second. Even moving that fast, getting across the observable universe, which spans about 93 billion light-years, still demands billions of years when measured by clocks here. Because distant galaxy light has been on its journey for such extended periods, anyone looking out there is actually seeing those galaxies as they existed long ago. The attached image is AI generated.
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