The laws of thermodynamics can tell us so much about the world around us!
The zeroth law tells us that two thermodynamic systems which are both in equilibrium with a third system are also in equilibrium with each other. This law wasn’t initially recognized as a separate law of thermodynamics, because it was implied in the other laws, but its articulation as a separate law is often useful in defining things like temperature. It tells us that thermodynamic equilibrium is an equivalence relation on a set of thermodynamic systems.
The first law of thermodynamics tells us that energy is not created or destroyed. Now that we have an equivalence between energy and matter, E=MC2, we know that this thermodynamic property applies to matter as well. All that ever will be already is, and nothing that is now will ever not be. How fun is that! This law tells us that no matter what we do, energy is a fixed value, we will never have no energy left.
The second law of thermodynamics tells us that entropy is always increasing. Entropy can be quantified using Boltzmann’s Entropy Formula, S = kB ln(W) where S is entropy, kB is Boltzmann’s constant, and W is the number of microstates in a given macrostate.The universe is always trending towards more entropy. The most probable configurations will continue to come into being. If the first law tells us what will remain in the unimaginable future, the second law tells us what we will lose. We will lose all that is unique, everything that has made our lives meaningful, our lives themselves, will eventually fade into the noise of the most probable configurations of the universe. You and I are so beautiful and astounding largely because we are unique. That is also why we are temporary.
The third law of thermodynamics tells us that as the temperature of a system approaches absolute zero, all processes cease and the entropy of the system approaches a minimum value. Our universe will never approach absolute zero, but it will approach equilibrium. It will approach a time where nothing changes. The energy and matter will always be there, but the cosmic-heat death of the universe awaits us. The beautiful complexity of the cosmos surrounds us, but it is not permanent. All of being is marching onward towards a crushing and deadly sameness. As much as we face our own mortality as individuals, we must face the mortality of our society, our planet, and our universe. All will end someday. It will not disappear, the energy will be there, but all that once made our universe our home will be coöpted into the subtle chaos that surrounds us. Dissolved into quiet murmurations in quantum fields of the cosmos.