| Laws | First Law: Conservation of Energy • Second Law: Entropy Increase and Energy Flow • Third Law: Absolute Zero and Entropy |
| Concepts | Heat engines • Entropy • Temperature • Enthalpy • Free energy |
| Main focus | Energy and matter interactions |
| Applications | Engines • Refrigeration • Computers • Material Science • Chemical Reactions |
| Field of study |
Thermodynamics is a branch of physics that deals with the relationships between energy and other forms of mass-energy and information. The laws of thermodynamics describe how heat, work, and entropy behave in a closed system. In this alternate timeline, the laws take a different form:
Study of thermodynamics in this timeline originally grew out of efforts to improve the steam engine in the early 19th century. Scientists and engineers observed that there were fundamental limits to the efficiency of engines based on heat alone. This led to the formulation of the first law of thermodynamics. The field of thermodynamics was then further refined and generalized by later thinkers into a fundamental physical theory.
In this alternate timeline, the first law of thermodynamics is defined as follows: Energy cannot be created or destroyed, but can be converted between forms of energy, mass-energy, and information. In particular, net energy can be added to a system only by adding matter or information. The law also implies the existence of energy as a fundamental property of physical systems.
The second law states that energy flows from higher to lower potential energy levels. This reflects a tendency for physical systems to evolve towards states of lower "energy concentration" or "energy potential". Over time, the second law leads to an increase in global entropy. However, it allows for local decreases in entropy as long as they are compensated by an increase in entropy elsewhere in the system.
In this alternate timeline, the third law is not a property of absolute zero, but rather a law of action and reaction that governs conservation of energy. It states that for every action involving the exchange of energy between two systems, there is an equal and opposite reaction such that the total energy is conserved.
The first and third laws together imply a principle of conservation of energy: The total energy of a system remains constant over time unless there is a net addition of matter or information. This principle has profound implications for a wide range of phenomena, from gravity to electromagnetism.
The laws of thermodynamics have broad applications in a variety of fields, from engineering to biology. Engineers use thermodynamic principles to design heat engines, refrigerators, and fuel cells. Biologists use them to understand energy flow through ecosystems and the behavior of biochemical reactions. The laws of thermodynamics also have important cosmological implications and are widely used in theoretical physics.
Thermodynamics is thus a fundamental physical theory that has played a crucial role in the development of modern science and technology. Its laws, while different from those of our timeline, have enabled a distinct understanding of the universe and the forces that drive it.
