Logarithm decibels. In a similar vein, the peak signal-to-noise ratio is commonly used to assess the quality of sound and image compression methods using the logarithm. The strength of an earthquake is measured by taking the common logarithm of the energy emitted at the quake. This is used in the moment magnitude scale or the Richter magnitude scale. For example, a 5.0 earthquake releases 32 times and a 6.0 releases 1000 times the energy of a 4.0. Another logarithmic scale is apparent magnitude. It measures the brightness of stars logarithmically. Yet another example is pH in chemistry; pH is the negative
Kardashev scale Kardashev scale The Kardashev scale is a method of measuring a civilization's level of technological advancement based on the amount of energy a civilization is able to use. It was proposed by Soviet astronomer Nikolai Kardashev in 1964. The scale has three designated categories: The scale is hypothetical, and regards energy consumption on a cosmic scale. Various extensions of the scale have since been proposed, including a wider range of power levels (types 0, IV and V) and the use of metrics other than pure power. In 1964, Kardashev defined three levels of civilizations, based on the order of magnitude