# Thread: The apogee of entropy

1. Is there a limit to how much entropy can occur in a closed system?

We know that heat is turned into infrared radiation constantly, which prevents the earth form overheating. The question though is, how cool could entropy bring an object if nothing interfered?

If you took a piece of metal at room temperature, suspended it in a vacuum, and used a one way light shield that would only allow light out, but not in, would the object eventually reach absolute zero, or only the temperature of its nearest surroundings?

I believe this would defy the laws of thermodynamics for a reason if it would reach absolute zero, but if that would not happen, I do not see why this experiment could not be done eventually.

2.

3. If you took a piece of metal at room temperature, suspended it in a vacuum, and used a one way light shield that would only allow light out, but not in, would the object eventually reach absolute zero, or only the temperature of its nearest surroundings?
Sounds like a modified Maxwell's Demon to me. Eventually you reach equilibrium as for practical reasons there is no such thing as an isolated system, let alone a "one-way-gate" for thermal radiation that in the end does not in one way or the other will interact with the "hotter" side of the isolated system.

4. They did in fact make a one way gate for massive particles, but not for electromagnetic radiation. This is only under the assumption that it is possible to do the same for EMR. Essentially the particle version somewhat reverses entropy and allows the particles to condense rather than to spread out. This creates a vacuum on one end.

5. Originally Posted by Cold Fusion
They did in fact make a one way gate for massive particles, but not for electromagnetic radiation. This is only under the assumption that it is possible to do the same for EMR. Essentially the particle version somewhat reverses entropy and allows the particles to condense rather than to spread out. This creates a vacuum on one end.
Yes, for parts of systems the entropy can in fact decrease, otherwise there would be no crystals. And if you decrease the entropy in a system you have to expend energy (=heat) someplace else thus in fact increasing the entropy of the universe by that. There is no such thing as a free lunch, remember.
And if you block the EMR one way there is interaction between the shield and the EMR and then the shild itself gets hotter so the system will heat up. No matter how you slice and dice it, Maxwell's Demon was based in fact on several assumptions that do not hold.

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