Johannes Kepler established that planets move in ellipses around the sun and derived phenomenological rules about planetary motion; Newton built on Kepler's observations to derive the inverse square law of gravity that explains Kepler's rules from first principles.

Einstein is underrated as a physicist because the history of physics selectively credits a small number of individuals while obscuring the reality that all very smart people, including Isaac Newton, were talking to other people and building on collective intellectual work.

Two years after Einstein's 1905 paper, mathematician Hermann Minkowski, who had been one of Einstein's professors, proposed that the correct interpretation of special relativity is to view space and time as a unified four-dimensional spacetime rather than separate entities, a mathematical reformulation Einstein initially dismissed as unnecessary but later recognized as useful for further development.

The difference between general relativity (primarily Einstein's accomplishment) and quantum mechanics (developed through contributions from dozens of physicists including Planck, Einstein, Rutherford, Bohr, de Broglie, Heisenberg, Schrödinger, Dirac, and others) demonstrates that the 'great man theory' is not characteristic of how physics is usually done; quantum mechanics involved many necessary pieces from many contributors.

In classical mechanics, there is no preferred position or velocity in the universe; the laws of physics work the same everywhere and at any velocity, a principle figured out by Galileo and incorporated by Newton.

The evolution of ideas in physics does not lock step with the evolution of people; different people have different ideas at different times and get them from different sources.

Before Newton, Aristotle claimed that things have natural places they want to be and natural ways they want to move, but Newton replaced this with the principle that objects not acted upon by force continue in straight lines at constant velocity, and those acted upon by force follow equations of motion.

Einstein's solution to the Maxwell-Newton conflict was to reject the idea that electromagnetic waves travel through a medium and instead take literally Maxwell's equations that predict everyone measures the same speed of light, which required completely reconceptualizing space and time.

Einstein was a physicist-focused rather than mathematics-focused character; he was very mathematically adept but learned only as much math as he needed because his primary interest was understanding physics, contrary to popular misconceptions that Einstein was poor at mathematics.

Einstein attempted to create a version of Newton's theory of gravity compatible with special relativity but found it impossible, which forced him to realize that gravity is not a force on top of spacetime but rather a feature of spacetime itself—specifically, spacetime geometry that is curved and dynamical, responding to the presence of mass and energy.

Different layers of reality depend on each other: quantum field theory and atoms form the foundation, which governs chemistry through electromagnetic interactions, which in turn enables biology, demonstrating a ladder of emergent complexity where each level depends on lower levels but must be studied on its own terms.

If William Shakespeare had never existed, his plays would never have been written, but if Albert Einstein had never existed, general relativity would still have been invented, likely without much delay, because physics progresses through the contributions of multiple brilliant people in the right place and time, not through irreplaceable individuals.

The inverse square law of gravity was not Newton's unique insight but was discussed by multiple contemporaries including Christian Huygens in the Netherlands and Robert Hooke; none of them had Newton's mathematical skill, and it took social pressure from Halley and others for Newton to write up his solution, resulting in the Principia Mathematica.

Different observers moving at different velocities through space will divide spacetime into space and time components differently, and there is no objective universal fact about what is happening simultaneously at distant locations—simultaneity is observer-dependent.

The many-contributor model of quantum mechanics development is actually much more characteristic of how physics is usually done than the single-person-inventing-everything model implied by the great man theory.

Maxwell's equations describe two fields pervading the universe: an electric field and a magnetic field, which James Clark Maxwell unified after work by Michael Faraday and others.

The equations of general relativity are so difficult that once Einstein wrote them down, others were able to solve them and extract their implications, suggesting that the intellectual content of scientific theories extends beyond the originator's initial understanding.

In classical mechanics under Newton's laws, space is absolute and agreed upon by everyone; this assumption held for hundreds of years before being challenged by Einstein's theories of relativity.

Einstein's equations of general relativity are so complex that Einstein initially believed no one might ever solve them, but Carl Schwarzschild, a German astronomer who attended Einstein's lectures in Berlin, taught himself general relativity, solved the equations for the gravitational field around the sun, and returned from World War I to present the solution to Einstein, who immediately recognized its brilliance.

Knowing that great discoveries emerge from social contexts helps us think more carefully about creating the best possible social context for making impressive discoveries in the future.