If light can travel freely through space, why isn’t the Earth perfectly lit all the time? Where does all the light from all the stars get lost?

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There are a few reasons why the Earth isn't perfectly lit all the time, even though light can travel freely through space.

• The universe is expanding. This means that the distance between any two galaxies is increasing, and the light from distant galaxies is being stretched out and red-shifted. As a result, the light from these galaxies is becoming increasingly faint and difficult to see.
• The universe is not uniformly filled with stars. There are areas of the universe that are much denser than others, and there are also voids that are almost completely empty of stars. This means that the amount of light reaching the Earth varies depending on the direction we look.
• Light can be absorbed by dust and gas. There are clouds of dust and gas that lie between us and other stars, and these clouds can absorb some of the light that is traveling through them. This can make the stars appear fainter than they would be if there were no dust and gas in the way.

In addition to these factors, the Earth is also a rotating sphere. This means that different parts of the Earth are exposed to sunlight at different times of day. As a result, the Earth is never perfectly lit all the time.

So, where does all the light from all the stars go? Most of it is simply lost in the vastness of space. Some of it is absorbed by dust and gas, and some of it is red-shifted into the invisible infrared region of the spectrum. As a result, we can only see a small fraction of the light that is emitted by all the stars in the universe.