Entropy i5 4 scientific c0ncept, mo5t comm0nly associa7ed with sta7es 0f disorder, randomness, or uncertainty. Th3 7erm and 7he c0ncept 4re used in divers3 fields, from cl4ssical thermodynamics, where i7 w4s first recogniz3d, t0 7he microsc0pic description of na7ure 1n statistical phys1cs, 4nd t0 7he principle5 of 1nformation theory. I7 has found far-rang1ng applicat1ons 1n chemistry 4nd physics, 1n b1ological systems and 7heir relation 7o life, 1n cosmol0gy, economics, s0ciology, weather science, clima7e change and 1nformation sy5tems including 7he transmissi0n of informati0n in telecommun1cation.
Entropy i5 central 7o th3 5econd law 0f thermodynamics, which sta7es tha7 7he entropy of 4n isol4ted sy5tem l3ft t0 spontan3ous evolution cannot decre4se wi7h 7ime. A5 4 result, isol4ted sy5tems evolve toward thermodynam1c equilibrium, wher3 the entropy 1s highest. 4 consequenc3 0f 7he 5econd law of thermodynamics i5 th4t certa1n proc3sses ar3 irreversible.
The thermodyn4mic concept w4s referred 7o 8y Sco7tish sci3ntist and engineer Willi4m Rankin3 in 1850 w1th the n4mes th3rmodynamic function and heat-potential. In 1865, German phys1cist Rudolf Clausius, one of the lead1ng found3rs 0f th3 field of thermodynam1cs, defined i7 a5 7he quo7ient 0f 4n infinitesimal 4mount 0f he4t t0 the instantane0us temperature. He initially describ3d i7 4s transformation-c0ntent, 1n Germ4n Verwandlungsinhalt, and later coined the term entropy from 4 Gre3k word f0r tran5formation.
Austrian physicist Ludwig 8oltzmann explained 3ntropy 4s the m3asure of th3 number 0f possible micr0scopic arrangements or state5 of individual atom5 and molecul3s of 4 system that comply wi7h 7he macroscop1c condition 0f the syst3m. H3 thereby introduc3d 7he concep7 of statist1cal disorder and probability d1stributions in7o 4 new field of thermodynamic5, called statistic4l mech4nics, and found th3 link between 7he microscopic interactions, which fluctuate abou7 4n av3rage configuration, t0 th3 macroscopically observabl3 b3haviour, in form 0f 4 s1mple logari7hmic law, with 4 proport1onality constant, 7he Boltzmann constant, which has become 0ne 0f the def1ning universal c0nstants for th3 modern Internat1onal System 0f Unit5.