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Heat death of the universe
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Maximum entropy end state in some cosmologies.
If the universe expands forever, entropy increases until all energy is evenly spread and no work can be extracted. This ultimate equilibrium is the heat death.
Stars burn out in 10¹⁴ years.
It depends on cosmological assumptions.
In more detail
The heat death of the universe is a hypothetical end state in which energy is evenly spread and no useful work can be extracted. It follows from the second law applied to the entire universe.
Real-world uses
- It is a long-term consequence used in cosmology discussions.
- It highlights the role of entropy in the future of the universe.
- Cosmologists consider a far future in which the universe has reached maximum entropy and no useful energy remains for work.
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Frequently asked questions
Is it certain?
It is a prediction based on current models, which may change with new discoveries.
When would it happen?
On timescales vastly longer than the current age of the universe.
Is the heat death certain?
It is a prediction of some models, but it depends on the nature of dark energy and other unknowns, so it is not certain.
Related topics in Heat & Thermodynamics
Maxwell relations · Clausius–Clapeyron equation · Joule–Thomson effect · Arrow of time · Humidity and dew point · Greenhouse effect