What fundamental concept causes us to see many distant stars as they were in the past, even if they are now extinct?

Answer

The finite speed of light traveling across immense spatial distances

Because light travels at a finite speed, the light reaching Earth from a star 5,000 light-years away left that star 5,000 years ago. Therefore, if the star died recently, we would continue seeing its past light for that duration.

What fundamental concept causes us to see many distant stars as they were in the past, even if they are now extinct?
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