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The constants listed here are known values of physical constants expressed in SI units; that is, physical quantities that are generally believed to be universal in nature and thus are independent of the unit system in which they are measured. Many of these are redundant, in the sense that they obey a known relationship with other physical ...
A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that cannot be explained by a theory and therefore must be measured experimentally. It is distinct from a mathematical constant , which has a fixed numerical value, but does not directly involve any physical measurement.
A mathematical constant is a key number whose value is fixed by an unambiguous definition, often referred to by a symbol (e.g., an alphabet letter), or by mathematicians' names to facilitate using it across multiple mathematical problems. [1]
A constant may be used to define a constant function that ignores its arguments and always gives the same value. [6] A constant function of a single variable, such as f ( x ) = 5 {\displaystyle f(x)=5} , has a graph of a horizontal line parallel to the x -axis. [ 7 ]
The circumference of a circle with diameter 1 is π.. A mathematical constant is a number whose value is fixed by an unambiguous definition, often referred to by a special symbol (e.g., an alphabet letter), or by mathematicians' names to facilitate using it across multiple mathematical problems. [1]
Physical constant, a physical quantity generally believed to be universal and unchanging; Constant (computer programming), a value that, unlike a variable, cannot be reassociated with a different value; Logical constant, a symbol in symbolic logic that has the same meaning in all models, such as the symbol "=" for "equals"
In physics, the fine-structure constant, also known as the Sommerfeld constant, commonly denoted by α (the Greek letter alpha), is a fundamental physical constant which quantifies the strength of the electromagnetic interaction between elementary charged particles.
Planck considered only the units based on the universal constants , , , and to arrive at natural units for length, time, mass, and temperature. [6] His definitions differ from the modern ones by a factor of 2 π {\displaystyle {\sqrt {2\pi }}} , because the modern definitions use ℏ {\displaystyle \hbar } rather than h {\displaystyle h} .