Strong interaction

In particle physics, the strong interaction is the mechanism responsible for the strong nuclear force (also called the strong force, nuclear strong force), one of the four known fundamental interactions of nature, the others being electromagnetism, the weak interaction and gravitation. Despite only operating at a distance of a femtometer, it is the strongest force, being approximately 100 times stronger than electromagnetism, a million times stronger than weak interaction and 10³⁸ times stronger than gravitation at that range. It ensures the stability of ordinary matter, confining quarks into hadron particles, such as the proton and neutron, the largest components of the mass of ordinary matter. Furthermore, most of the mass-energy of a common proton or neutron is in the form of the strong force field energy; the individual quarks provide only about 1% of the mass-energy of a proton.

The strong interaction is observable in two areas: on a larger scale (about 1 to 3 femtometers (fm)), it is the force that binds protons and neutrons (nucleons) together to form the nucleus of an atom. On the smaller scale (less than about 0.8 fm, the radius of a nucleon), it is the force (carried by gluons) that holds quarks together to form protons, neutrons, and other hadron particles. In the latter context, it is often known as the color force. The strong force inherently has such a high strength that hadrons bound by the strong force can produce new massive particles. Thus, if hadrons are struck by high-energy particles, they give rise to new hadrons instead of emitting freely moving radiation (gluons). This property of the strong force is called color confinement, and it prevents the free "emission" of the strong force: instead, in practice, jets of massive particles are observed.

Michio Kaku

Michio Kaku (/ˈmiːtʃioʊ ˈkɑːkuː/; born January 24, 1947) is a Japanese-American futurist, theoretical physicist and popularizer of science. Kaku is a Professor of Theoretical Physics at the City College of New York. He has written several books about physics and related topics, has made frequent appearances on radio, television, and film, and writes online blogs and articles. He has written three New York Times Best Sellers: Physics of the Impossible (2008), Physics of the Future (2011), and The Future of the Mind (2014). Kaku has hosted several TV specials for the BBC, the Discovery Channel, the History Channel, and the Science Channel.

Early life and education

Kaku was born in San Jose, California, to Japanese American parents. His father, born in California and educated in both Japan and the United States, was fluent in Japanese and English. Both his parents were interned in the Tule Lake War Relocation Center during World War II, where they met and where his older brother was born.