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The balance of nature, also known as ecological balance, is a theory that proposes that ecological systems are usually in a stable equilibrium or homeostasis, which is to say that a small change (the size of a particular population, for example) will be corrected by some negative feedback that will bring the parameter back to its original "point of balance" with the rest of the system.
A celestial map from the 17th century, by the Dutch cartographer Frederik de Wit. Natural philosophy or philosophy of nature (from Latin philosophia naturalis) is the philosophical study of physics, that is, nature and the physical universe while ignoring any supernatural influence.
Motile marine animals are commonly called free-swimming, [10] [11] [12] and motile non-parasitic organisms are called free-living. [13] Motility includes an organism's ability to move food through its digestive tract. There are two types of intestinal motility – peristalsis and segmentation. [14]
The vacuum state of the "free" electromagnetic field (that with no sources) is defined as the ground state in which n kλ = 0 for all modes (k, λ). The vacuum state, like all stationary states of the field, is an eigenstate of the Hamiltonian but not the electric and magnetic field operators.
This vacuum state is called high vacuum, and the study of fluid flows in this regime is called particle gas dynamics. The MFP of air at atmospheric pressure is very short, 70 nm , but at 100 mPa (≈ 10 −3 Torr ) the MFP of room temperature air is roughly 100 mm, which is on the order of everyday objects such as vacuum tubes .
The change in the free energy is the maximum amount of work that the system can perform in a process at constant temperature, and its sign indicates whether the process is thermodynamically favorable or forbidden. Since free energy usually contains potential energy, it is not absolute but depends on the choice of a zero point. Therefore, only ...
A reservoir is a thermodynamic system which controls the state of a system, usually by "imposing" itself upon the system being controlled. This means that the nature of its contact with the system can be controlled. A reservoir is so large that its thermodynamic state is not appreciably affected by the state of the system being controlled.
The strength and range of the electric force and the good conductivity of plasmas usually ensure that the densities of positive and negative charges in any sizeable region are equal ("quasineutrality"). A plasma with a significant excess of charge density, or, in the extreme case, is composed of a single species, is called a non-neutral plasma ...