Edward Witten tells us a string theory, an attempt we make to make sense to all the phenomena we see in nature in terms of one unified theory, so 20th-century physicists understood reality or as much as we know reality in term of two big theories………..
“Edward Witten (/ˈwɪtən/; born August 26, 1951) is an American theoretical physicist and professor of mathematical physics at the Institute for Advanced Study in Princeton, New Jersey.
Witten is a researcher in string theory, quantum gravity, supersymmetric quantum field theories, and other areas of mathematical physics.
In addition to his contributions to physics, Witten’s work has significantly impacted pure mathematics. In 1990 he became the first and so far the only physicist to be awarded a Fields Medal by the International Mathematical Union. In 2004, Time magazine stated that Witten is widely thought to be the world’s smartest living theoretical physicist.” Source: https://en.wikipedia.org/wiki/Edward_Witten