Phenomena exert forces on objects directly and instantaneously.

Classical Physics…

… tracks objects through space and time

… generates deterministic predictions

… uses continuous quantities

19th Century

1808 John Dalton revived the atomic theory to explain chemical phenomena

1864 Theory of Electromagnetism

Charged particles exert forces on other charged particles, indirectly by electric and magnetic fields propagating at the speed of light.

20th Century

1897 The first subatomic particle, the electron, was discovered

1905 Special Relativity

The speed of light is the same in all non-accelerating reference frames, with the result that;

The elapsed time of an event may be different in different reference frames

The length of a rod may be different in different reference frames

1911 Rutherford’s Planetary Model of the Atom

Rutherford’s idea was that the electromagnetic force from nuclear protons keeps the electrons in orbit, just as the gravitational force from the Sun keeps the planets in orbit.

The idea fails because, per the laws of electromagnetism, the orbiting electrons would quickly lose energy and crash into the nucleus.

1915 General Relativity

The core idea of General Relativity, Einstein’s theory of gravitation, is that gravity is the curvature of spacetime.

1925 Quantum Mechanics

In contrast to Classical Mechanics, Quantum Mechanics…

… does not track particles through space and time

… generates probabilistic predictions

… uses discrete (quantized) quantities

Sean Carroll: the two greatest revolutions in physics:

Newton’s development of classical mechanics in the 1600s

The replacement of Newton’s theory with Quantum Mechanics

1940s Quantum Electrodynamics (QED)

QED governs the electromagnetic interaction

1960s Electroweak Theory (EWT)

EWT governs the weak and electromagnetic interactions

1973 Quantum Chromodynamics (QCD)

QCD governs the strong interaction

1975 Standard Model of Particle Physics (SMPP)

The Standard Model postulates

Quantum Fields and their particles

The equations governing their behavior, Quantified Field Theory