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I would say that the biggest message from modern science should be contrasted with the older school of thought represented by Aristotle, which was that of an eternal, unchangeing Universe, that the Universe always existed and always will.

2
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Modern science now tells us that this is false.

3
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It is wrong on every level.

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The Universe did not always exist. It has an age: 13.7 billion years.

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Don't ask me what came before it; I have no idea and there's no way I can answer that.

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But the point is, it has an age and in this age it has a history. It changes. It is not always the same. It changes and it changes remarkably.

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The history of the Universe is a history of cooling: it began with temperatures in the billions and billions of degrees and it is continuously getting colder.

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It's a history of rarification: galaxies are moving apart, so there is less and less matter in a given volume.

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It is a history of darkening: in the beginning it was extremely bright, at that point in time we call the Big Bang (that notion of an explosion).

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Today, the Universe is becoming blacker – the night is getting darker – on a scale of billions of years. I'm not referring to light pollution: that's what humans do.

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I am talking about the whole Universe.