Hypothetical questions with a closed system

[twain]

The 2nd law of thermodynamics refers to closed systems.

1. If we imagine a universe of infinite extent but where only one object exists that emits e/m waves, is that a closed system?

2. If we imagine a universe where only two asteroids exist and are orbiting each other, and a machine between them converts their gravitational energy into e/m waves that are emitted to space, does this system have zero increase in entropy?

3. If life on the asteroids absorbs some of the e/m waves and begins to add structure to the asteroids, is the entropy decrease due to life negligible compared to the entropy increase due to e/m waves partly turning to heat?

 

[russ_watters]

1. Yes.
2. This question makes no sense. What do you mean by "gravitational energy"?
3. Yes. Note: EM waves are heat, they don't 'turn into' heat.

 

[twain]

2. This question makes no sense. What do you mean by "gravitational energy"?

If they get closer to each other, gravitational energy will be less, and that can theoretically be exploited by a machine to convert the energy into another form, just like damns convert the gravitational energy of water into electricity.

3. Yes. Note: EM waves are heat, they don't 'turn into' heat.

Wrong word, I meant warmth or the property of being hot, not heat. So the question is:

3. If life on the asteroids absorbs some of the e/m waves and begins to add structure to the asteroids, is the entropy decrease due to life negligible compared to the entropy increase due to e/m waves partly warming up matter?

 

[twain]

By the way, the e/m waves in the hypothesis are not restricted to visible light or infrared. What if they are just 1 MHz radio waves and life somehow manages to get energy out of them?

 

[russ_watters]

If they get closer to each other, gravitational energy will be less, and that can theoretically be exploited by a machine to convert the energy into another form, just like damns convert the gravitational energy of water into electricity.

If you harness the gravitational potential energy to transfer energy to another form, you increase the entropy of the universe.

By the way, the e/m waves in the hypothesis are not restricted to visible light or infrared.

Correct.

What if they are just 1 MHz radio waves and life somehow manages to get energy out of them?

All radiated em radiation carries entropy.

 

[Pythagorean]

2. If we imagine a universe where only two asteroids exist and are orbiting each other, and a machine between them converts their gravitational energy into e/m waves that are emitted to space, does this system have zero increase in entropy?

No, the entropy of the system still increases.

Note that the orbital system loses energy as it's converted into an EM system (so the asteroids come closer and closer, as energy is drained from the system... it will require another energy source to separate them again, so it's a one time shot...

and both the orbital system and the EM system lose energy (through the conversion machine's operation) in the form of heat. That is what entropy can be equated to: the energy that is lost when trying to convert one kind of energy into another.

beyond classical physics:
after a long time, the system will theoretically reach http://en.wikipedia.org/wiki/Heat_death_of_the_universe" by then.

 

[russ_watters]

Locking thread since it is basically identical to the other one...