Issues

Practically every element in the periodic table can be detected, down to single‐atom sensitivity, by resonance‐ionization‐spectroscopy methods involving commercially available lasers.

At sufficiently small distances, perhaps less than $10−29 cm,$ the weak, electromagnetic, and strong interactions appear to be no more than different components of the same fundamental force.

A decade of observations by Earth‐orbiting satellites has led to the discovery of compact, hot components in many stellar systems and extended coronas surrounding our Galaxy and others.