BBC Sky at Night

Telescopes as time machines

ecause of the finite speed of light, we see distant objects as. However, to cosmologists it's a wonderful gift of nature. Thanks to the lookback time, they are able to study the early youth of the Universe. All you need to do is to look very far away into space and you're automatically looking far back in time. Thus, the full 13.8-billion-year history of the Universe becomes accessible to scientific inquiry.

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