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In the 1920s, theoretical physicists, most notably Albert Einstein, considered the possibility of a cyclic model for the universe as an (everlasting) alternative to the model of an expanding universe. However, work by Richard C. Tolman in 1934 showed that these early attempts failed because of the cyclic problem; according to the Second Law of Thermodynamics, entropy can only increase.

The snippet of this wikipedia article mentions why the cyclic model failed by virtue of the Second Law of Thermodynamics. In this context, do we need to be assured that the law certainly needs to hold?

To elaborate, is it hypothetically possible that on such a scale the Second Law necessarily may not hold true?

Qmechanic
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Maan
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1 Answers1

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The second law essentially just says the most likely thing that can happen will happen. If this law is violated for the universe then there would need to be some sort of external influence that makes this not the case. In other words, treating the universe as an entire system, it couldn't be a closed system so that something external could lower the entropy of the universe

BioPhysicist
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