Is the universe eternal?
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The question of whether the universe is eternal is a profound and complex one, often explored in the context of physics and cosmology rather than having a definitive answer.
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Eternal but Non-Repetitive Universe: Theoretical physicist discusses the idea that if the universe is eternal, it might be in a non-repetitive sense, similar to the series of integers which never repeat despite being infinite. This concept challenges the idea of eternal recurrence, suggesting that an infinitely repeating universe would likely manifest mostly as low entropy fluctuations, which our universe does not align with according to current understanding 1.
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Steady State Theory and Observational Challenges: Historically, the "steady state theory" posited that the universe has always existed in a constant state. However, this theory faced challenges based on observational evidence, such as the darkness of the night sky which contradicts the expectation of a uniformly bright sky if the universe were infinite and eternally filled with stars. This paradox suggests the universe might not be eternally old or infinite 2.
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Energy Considerations and Time: Carroll also discusses scenarios where the universe might have zero total energy, leading to no net time evolution according to certain cosmological models. This presents a universe not changing over time, potentially supporting an eternal existence in a very different sense from our everyday understanding of dynamics and evolution 3.
These discussions highlight that while the universe might be eternal in some sense, the specifics of its eternity — whether it features eternal repetition, or exists in a static or dynamically varying state — are subject to significant scientific debate and inquiry. The answer hinges on complex cosmological theories and observations, and remains an active area of research and philosophical contemplation.
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