It is... convenient to state Coulomb's law in modern terms, first used... by James Clerk Maxwell. The electric force... is always proportional to the… - Steven Weinberg

Electrons are believed to be absolutely stable, and protons and neutrons (when bound...) live at least 10³⁰ years. With few exceptions, all other particles have very short lifetimes...

... there are particles ... that we have never seen in a laboratory but astronomers tell us make up most of the matter in the universe — the so-called . It's dark because it doesn't radiate — it doesn't interact with light. We just know about it because of its gravitational field. What is the dark matter? ... We have a lot of ideas — all going in different directions. We don't know which is the right idea.

The reader may... wonder why when amber is rubbed with fur the electrons go from the fur to the amber, but when glass is rubbed with silk the electrons go from the glass to the silk? ...[W]e still don't know. The question involves the physics of surfaces of complex solids... In a purely empirical way, there has been developed... the triboelectric sequence... The electrification is most intense for objects... well separated in the... sequence. ...It is ironic that we still do not have a detailed understanding of frictional electrification, even though it was the first... to be studied... But... often... science progresses... by selecting problems that are as free as possible from irrelevant complications and... provide opportunities to get at fundamental principles...