In this video, we're going to introduce the second law of thermodynamics. The second law of thermodynamics can actually be stated in many different ways, and it's possible that your professor or your textbook might state the second law of thermodynamics in a different way. But really, all the second law of thermodynamics is trying to say is that 100% efficient energy conversion is impossible since heat energy is going to be lost with every energy transfer, and this is going to lead to the increase of the overall universal entropy. Heat is defined as a form of kinetic energy that is transferred between two objects with different temperatures.
Let's take a look at our example below at the second law of thermodynamics to get a better understanding of it. Notice that we're showing you a similar process to our last lesson video on the first law of thermodynamics. You can see that the sun is the energy provider where most of the energy originates for life. The energy transfer here, from solar energy to plants, is going to be accompanied by a loss of heat. With every energy transfer, some of the energy is lost as heat.
There is not a 100% efficient energy conversion. Some of the energy is lost as heat, and that heat is not a usable form of energy by the organism. The same goes for when an organism eats the leaf; the energy transfer here is going to be accompanied by a loss of heat. The same is true when the fox eats the mouse. There's going to be a transfer of energy, but some of it will be lost in the form of heat.
This heat that is being lost with every energy transfer is going to lead to the increase in the entropy of the universe. The entropy of the universe is always increasing with every energy transfer. This is really what the second law of thermodynamics is referring to: the increasing of universal entropy with every energy transfer. This concludes our introduction to the second law of thermodynamics and we'll be able to apply some of the concepts that we've learned here as we move forward in our course. I'll see you all in our next video.