The kind of radiation discussed in this document is called because it can produce charged particles (ions) in matter. Unstable atoms differ from stable atoms because unstable atoms have an excess of energy or mass or both.Radiation can also be produced by high-voltage devices (e.g., x-ray machines). The kinds of radiation are electromagnetic (like light) and particulate (i.e., mass given off with the energy of motion).
He anticipated that the ‘wilder races’ would become extinct because survival of the fittest meant they would be superseded by the evolutionarily-advanced ‘civilised’ races.
Beta and alpha radiation are examples of particulate radiation.
Interestingly, there is a "" of natural radiation everywhere (ubiquitous) in our environment.
(See History below.) The realization of the standard second is described briefly in a special publication from the National Institute of Standards and Technology, The earliest clocks to display seconds appeared during the last half of the 16th century.
The second became accurately measurable with the development of mechanical clocks keeping mean time, as opposed to the apparent time displayed by sundials.