![]() ![]() So light lost to distance does not account for the darkness of night. If the distance between A and B is 2 units, then each square in A is one-fourth as bright as each square in B but there are four times as many squares in A as there are in B. The same amount of light should reach Earth from each layer, because although the amount of light to reach us from each star decreases with distance (by 1/d^2), the number of stars in each layer increases, effectively balancing out the distance effect. To fully understand the perplexity, picture stars of equal brightness distributed evenly in concentric layers around Earth, like shells around a nut. (Heinrich Olbers was a German astronomer who popularized discussion of this subject in 1826.) You might think that the question can be explained away by the effect of distance - not so. ![]() It's actually a famous cosmological problem, formally known as Olbers' Paradox. The answer to this seemingly simple question may boggle your brain. ![]() If Star Layer A is twice as far from Earth as Star Layer B, then the amount of light that reaches us from each star in A is only one-fourth the amount of light that reaches us from each star in B but there are four times as many stars in A as there are in B. ![]()
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