What does modern physics mean?

Hint: Let us first get some idea about physics. Physics is a natural science that examines matter, its mobility and behaviour in space and time, as well as energy and force, which are related concepts. Physics is one of the most fundamental scientific fields, with the primary purpose of understanding how the universe functions.

Complete step-by-step solution:
Modern physics is a discipline of physics that was established in the early twentieth century and onward, or that was affected strongly by early twentieth-century physics. Quantum mechanics, special relativity, and general relativity are all important branches of modern physics.
Modern physics is an attempt to comprehend the underlying mechanisms of matter interactions using scientific and engineering methods. The word "modern physics" literally means "up-to-date physics." In this sense, most of what is known as classical physics is actually modern. New discoveries, particularly the advent of quantum mechanics (QM) and relativity, have generated important paradigm shifts since around\[1890\]. (ER). Modern physics is defined as physics that combines components of either QM or ER (or both). The phrase is most commonly used in this latter context.

Note:When coping with harsh situations, modern physics is frequently used. When dealing with "lows" (low temperatures, short distances), quantum mechanical effects tend to occur, while relativistic effects tend to appear when dealing with "highs" (high velocity, big distances), with "middles" being classical behaviour.