Life is sometimes described as a constant struggle against the second law of thermodynamics. How do organisms succeed in this struggle without violating the second law?
As organisms grow and develop, they maintain they maintain a high level of order and do not appear to be more disorganized. However organisms maintain their degree of order over time only with the constant input of energy from their surroundings. That is why plants most photosynthesis and animals should eat. Although the order within organisms may tend to increase temporarily, the total entropy of the universe (organisms plus surroundings) always increases over time.
To understand how organisms succeed in the struggle against the second law of thermodynamics, it's important to have a basic understanding of the second law itself. The second law of thermodynamics states that in any isolated system, the total entropy (a measure of disorder) always increases over time. In simpler terms, systems tend to move from a state of order to a state of disorder.
Living organisms, including plants, animals, and humans, are not isolated systems. They interact with their environment, exchange energy and matter, and maintain a relatively stable internal structure and organization. This is achieved by constantly taking in energy from the environment, in the form of sunlight or food, and utilizing it to perform various biological processes.
Organisms succeed in the struggle against the second law by regularly replenishing and restoring the order within their own systems. They do this through various processes, including:
1. Metabolism: Organisms convert energy from their surroundings into usable forms, such as ATP (adenosine triphosphate), through metabolic reactions. These reactions involve breaking down complex molecules and building new ones, utilizing the energy input to maintain order and carry out vital functions.
2. Homeostasis: Living organisms actively regulate their internal environment to maintain a relatively constant and orderly state. This includes maintaining a stable body temperature, pH levels, and ion concentrations, among other factors. Homeostasis helps prevent the system from descending into disorder and chaos.
3. Reproduction and Evolution: Organisms have the ability to reproduce and pass on their genetic information to their offspring. Through the process of reproduction, organisms can perpetuate ordered structures and functions, ensuring the continuation of life. Over time, populations of organisms can also undergo evolutionary changes, leading to increased efficiency and adaptation.
It's important to note that while organisms can locally reduce entropy within their own systems, the overall entropy of the universe (including the environment they interact with) still increases. By extracting energy from their surroundings and using it to maintain order within their systems, organisms effectively create a local decrease in entropy at the expense of increasing the global entropy.
In summary, living organisms succeed in the struggle against the second law of thermodynamics by constantly replenishing energy, maintaining order through metabolic processes and homeostasis, and reproducing to perpetuate ordered structures. While they cannot violate the second law, their existence is dependent on the constant flow of energy and the maintenance of a delicate balance between order and disorder.