By the second law of thermodynamics, you shouldn't be able to use any amount of mirrors/lenses to focus sunlight onto an object and heat it past the surface temperature of the sun (approximately 5800K).
In principle this makes sense to me, but I'm more concerned with the mathematics behind this. Whenever I stop to think about energy, things seem to break down in my mind. I just can't get past the fact that the more rays of light your focus (ie, the more photons), the more energy that would be passing into your system. If you increase the energy of your system, is seems like the average energy of the molecules in your system will continue to increase.
Can anybody show me a mathematical counterexample? I guess I just don't understand all of the equations that necessarily go into this calculation, because I keep getting that the energy of your system increases with each photon that passes into your system. Thanks!
If you believe my statement is incorrect, please look at problem 91 here and explain why I'm incorrect and how the answer is E http://www.physics.ohio-state.edu/undergrad/greStuff/exam_GR9677.pdf