<Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> In a literal sense, the term modern physics, means up - to - date physics . In this sense, a significant portion of so - called classical physics is modern . However, since roughly 1890, new discoveries have caused significant paradigm shifts: the advent of quantum mechanics (QM) and of Einsteinian relativity (ER). Physics that incorporates elements of either QM or ER (or both) is said to be modern physics . It is in this latter sense that the term is generally used . </P> <P> Modern physics is often encountered when dealing with extreme conditions . Quantum mechanical effects tend to appear when dealing with "lows" (low temperatures, small distances), while relativistic effects tend to appear when dealing with "highs" (high velocities, large distances), the "middles" being classical behaviour . For example, when analysing the behaviour of a gas at room temperature, most phenomena will involve the (classical) Maxwell--Boltzmann distribution . However near absolute zero, the Maxwell--Boltzmann distribution fails to account for the observed behaviour of the gas, and the (modern) Fermi--Dirac or Bose--Einstein distributions have to be used instead . </P> <Ul> <Li> <P> German physicist Albert Einstein, founder of the theory of relativity </P> </Li> <Li> <P> German physicist Max Planck, founder of quantum theory </P> </Li> </Ul>

Who wrote the book that got modern physics started