Thermodynamics ...for Kids!

3 Laws of Thermodynamics

Thermodynamics is the study of heat, energy, and motion. Thermo refers to temperature, (think of the word thermometer!), and dynamics means energy in motion. (Think dynamite-a powerful explosion of energy!) The three laws of thermodynamics help us understand how heat, energy, and motion work within the universe.

1st Law of Thermodynamics:
Energy cannot be created or destroyed.

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The 1st law of thermodynamics says energy cannot be created or destroyed. This law helps us understand that energy never disappears or goes away, it only gets moved around, or used in different ways. Imagine having a collection of blocks. You could use your blocks to build a really nice tower! Or you could use your blocks to build an animal figure. Or maybe you would use your blocks to make an airplane. No matter how you used the blocks, you would still have the same number of blocks. Even if you lost a block under the couch, or your neighbor borrowed some of them, there would still be the same number of blocks! Energy might move around, or be used in different ways, but you can never create more energy, or destroy energy— there will always be the same amount of energy in the universe, as if God gave the universe a certain number of blocks.

3rd Law of Thermodynamics:
Entropy of a perfect crystal at absolute zero is zero.

What does this mean? It means that if you could get perfectly organized atoms cold enough to be perfectly frozen, without any movement, then they will no longer move, change, or become disorganized. This law teaches us the idea of absolute zero, and it teaches us the relationship between entropy and temperature.

Absolute zero is 0 Kelvin, or -459.67 degrees Fahrenheit. But as far as we can tell, we can never reach absolute zero. In fact, scientists used lasers to cool individual atoms to 1⁄2 kelvin, but even they couldnʻt reach absolute zero. It is impossible to reach absolute zero because molecules will always move, and like we said before in the 2nd law, heat will always move from a hotter to a cooler. So no matter how hard they try, scientists canʻt keep heat from the molecules.

So why do we even have this crazy impossible law?!? This law helps us understand the ability of atoms to be random. This law helps us understand that motion, heat, and order are related. The more molecules can move around, the more heat they create, and the more entropy (or disorder). The more you study heat and energy and work, the more these laws help us understand what is happening in the universe.

Lastly, this law shows us that nothing in the universe is perfect. We all need grace, because we all have the tendency to be broken, disordered, and wearing down. We are all imperfect human beings, but the God of the universe offers his perfect love to all of us, doing his mighty work of healing and brining us into complete wholeness. That’s pretty much the best news in the whole universe.