Thermo warm-up

If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations---then so much the worse for Maxwell's equations. If it is found to be contradicted by observation---well these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.
Sir Arthur Stanley Eddington

Problem 1

When designing a suit for open space, what should ingeneers be more careful of -- heating of heat extraction?

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Problem 1

Estimate a number of photons in gas oven under room temperature (?) and under maximum heat.

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Problem 1

Estimate the temperature at the surface of the Sun, assuming that the Erath with mean temperature at its' surface $15\,C^\circ$ is in thermal equilibrium with the Sun.

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Problem 1

What is the difference between entropy of gravitational degrees of freedom and ordinary entropy (e.g., entropy of ideal gas)?

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Problem 1

One of the most used classifications divide physical systems into open and isolated. The entropy in an isolated system could only increase, eventually reaching the thermal equilibrium. In contrast, due to external interactions entropy in open systems could decrease, for example, through an absorption of a component with low entropy. Explain, why the Sun is a source of low entropy for the Earth.

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