![]() ![]() The Second Law is not only a useful way of thinking about life (at least, for a physicist like me), it also has a rather unusual status as the most ‘theological’ of all physical laws. But importantly, the Second Law is still obeyed, and the organism lives on. So entropy increases overall, while the organism remains a little bubble of negative entropy in a sea of disorder. It then makes use of the Second Law by processing the negative entropy and expelling it in the form of positive entropy. An organism can only do this by taking in negative entropy itself, in the form of complex foods and concentrated energy. Life is the process of resistance to this inevitable decay, the maintenance of a state of negative entropy with respect to the surroundings, far from equilibrium with them. This turns out to provide a reasonably straightforward way into an otherwise notoriously-difficult problem – how to define life.Įrwin Schroedinger explained in his classic book What is Life? that death is the point at which an organism begins to come to a state of maximum entropy, reaching equilibrium with its surroundings by cooling and decaying until it’s indistinguishable with them. Arguably the most important of all the laws of physics (at least where biological life is concerned), the Second Law of Thermodynamics declares that the entropy (disorder) of a closed system (one that is thermally insulated from its surroundings) can never decrease, but must always increase (or at the very least stay the same). Personal pride, and the emerging scholarly consensus, require me to point out that I have since been proved right in what I was trying to say back then, but the intervening 15 years have taught me that neither I nor my eminent colleague had a full grasp of the mysteries of entropy, still less its mystical (what I might now refer to as ‘theological’) overtones.Įntropy is what makes life worth living. Ever since then, I’ve been fixated with trying to really understand entropy. As a system becomes more disordered, the lower its energy and the higher its entropy become.Some 15 years ago, as a young researcher trying to push a new idea, I was accused publicly by a much more eminent fellow physicist of not understanding entropy. Entropy is a measure of the disorder of a system. The more ordered a system is, the lower its entropy. It takes energy to make a system more ordered. Systems can be thought of as having a certain amount of order. Everything outside of the system is called the surroundings. In studying energy, scientists use the term “system” to refer to the matter and its environment involved in energy transfers. The laws of thermodynamics govern the transfer of energy in and among all systems in the universe. Like all things in the physical world, energy is subject to the laws of physics. Energy is exchanged between them and their surroundings, as they consume energy-storing molecules and release energy to the environment by doing work. A closed system is one that cannot transfer energy to its surroundings.īiological organisms are open systems. The stovetop system is open because heat can be lost into the air. ![]() An open system is one in which energy can be transferred between the system and its surroundings. There are two types of systems: open and closed. Energy is transferred within the system (between the stove, pot, and water). For instance, when heating a pot of water on the stove, the system includes the stove, the pot, and the water. The matter and its environment relevant to a particular case of energy transfer are classified as a system, and everything outside of that system is called the surroundings. Thermodynamics refers to the study of energy and energy transfer involving physical matter. Distinguish between an open and a closed system. ![]()
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