How will the Universe end?

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1. An unbreakable law

Follow this journey to the end and you can lay waste to the Universe in just a few seconds. It’s all to do with the second law of thermodynamics, which was framed in the mid-19th Century.

The second law was a major step forward for science, but it also felt like one giant leap backwards for humankind. It brought with it some very unpleasant news. It involved a quantity new to science called ‘entropy’ and predicted nothing less than something called the 'heat death' of the Universe. As TS Eliot wrote: “This is the way the world ends, not with a bang but a whimper.”

This is where our current understanding of the Universe stands, but there’s no need to worry. Heat death won’t happen for trillions of years, which gives us plenty of time to get to grips with the second law, one of the most important of all scientific principles. Now take the next step and join me on board the entropy train.

2. The second law of thermodynamics

It was the steam age that made scientists think hard about the physics of heat. The second law, which states that the entropy of the Universe tends to a maximum, was one of the consequences of understanding how steam engines work.

All aboard the entropy express.

Today steam power seems like ancient history... but it still has a lot to tell us about the present and the future.

3. The impact of the second law

Clausius' framing of the second law of thermodynamics made people sit up and think. Philosophers and writers have tried to come to terms with its implications.

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The second law challenged the concept of progress and even cast doubt over religious faith.

4. Life and the second law

If the Universe and everything in it is heading in the same direction towards death, how do we explain life and civilisation?

Entropy is time's arrow.

5. The heat death of the Universe

Journey trillions of years into the future in just seconds as you watch the stars go out and the temperature of the Universe drop until everything is at one dead level.

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6. How does the second law make you feel?

We know from bitter experience that everything organic must one day die, which is why entropy has always begged important questions about life and death.


Can we learn anything from the second law about how we live and organise ourselves?

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Some people think of the physics as a metaphor that suggests a diverse society is much more likely to be healthy and vital than one that is homogeneous.


Industrial society is powered by fossil fuels that burn and will one day be exhausted.

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Entropy lies at the heart of our environmental concerns. The second law proves that there is indeed no such thing as a free lunch.


Does the second law undermine some fundamental religious beliefs?

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In the 19th Century the vision of heat death was a bombshell. It still has the power to trouble people who believe in eternal life and a world without end.