Fast Radio Bursts

Fast Radio Bursts are one of the most remarkable astronomical discoveries of recent years, if all doubts as to their astronomical nature can be laid to rest. These millisecond bursts have dispersion measures that indicate cosmological distances and brightness temperatures as high as 10^{37} K (10^{21} ergs). Such brightness temperatures can only be produced by collective motions of charges ('bunches'), as is familiar for radio pulsars. Both the emission mechanism and the astronomical environment remain mysterious.