Idea 2 for how to break the second law of thermodynamics

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Discussion Overview

The discussion revolves around a proposed idea for violating the second law of thermodynamics, specifically through a hypothetical thought experiment involving two bodies at the same temperature with differing capacities for emitting electromagnetic radiation. The focus is on theoretical implications rather than practical applications.

Discussion Character

  • Exploratory
  • Debate/contested

Main Points Raised

  • One participant presents a thought experiment suggesting that if one body has a larger opening for electromagnetic radiation to escape, it could lead to a situation where the cooler body absorbs more radiation than it emits, potentially violating the Clausius statement of the second law.
  • Another participant clarifies that if the bodies are perfect mirrors, they would not absorb any radiation and therefore could not heat up, challenging the initial premise of the thought experiment.
  • A further clarification is made regarding the setup of the experiment, emphasizing the role of the mirrors and the warm body emitting radiation.
  • A moderator notes that discussions on perpetual motion machines are not acceptable within the forum, indicating a boundary on the topic's validity.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of the proposed thought experiment, with some questioning the assumptions made about perfect mirrors and radiation absorption. The discussion remains unresolved regarding the validity of the idea presented.

Contextual Notes

The discussion highlights limitations related to the assumptions of perfect mirrors and the theoretical nature of the thought experiment, which may not hold under practical conditions.

Bobcent
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Hello!

I have another idea for how to break the second law of thermodynamics, and I don't see where this one cracks either. I would be glad if someone could explain this to me.

Kelvin-Planck statement of the second law:

"No process is possible whose sole result is the absorption of heat from a reservoir and the conversion of this heat into work."

Clausius statement of the second law:

"No process is possible whose sole result is the transfer of heat from a cooler to a hotter body."

Here it goes:

First see the drawing below:

vnmdds.jpg


As you can see on the drawing, the right body has a bigger opening for EM radiation to escape than the left body does. The two bodies start of at the same temperature. But if more EM radiation goes from the right body to the left body, than vice versa, with time, the left body will heat up, and the right body will cool down. This clearly violates the second law, see Clausius statement above.

This is a hypothetical thought experiment. I realize the practical problems with perfect mirrors and lenses, but theoretically it should be possible?

Grateful for help!
 
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Some clarification:
If the bodies are the perfect mirrors, then they do not absorb any radiation, and cannot heat up.
 
256bits said:
Some clarification:
If the bodies are the perfect mirrors, then they do not absorb any radiation, and cannot heat up.

To clarify:

The black dot in the middle is the body which emits radiation from being warm. The half circle, and the circle with a little opening, as indicated in the drawing, are the mirrors
 
Perpetual motion machines are not an acceptable subject here - please reread the PF Rules. We let the first thread stand because we had hoped to educate you on why they were impossible, but we will not have a parade of PMMs here.
 

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