Which of the following statements about gamma ray bursts is not true?

The statement that the events responsible for gamma ray bursts apparently produce only gamma rays, and no other light that we can hope to detect, is not accurate because gamma ray bursts (GRBs) are often observed to emit a range of electromagnetic radiation, not just gamma rays. In fact, after the initial burst of gamma rays, GRBs can produce afterglow emissions in X-rays, optical, and radio wavelengths. These afterglows allow astronomers to study GRBs in much more detail and can be detected much later than the initial burst, giving us valuable information about these phenomena. This ability to detect other forms of light from a gamma ray burst is crucial in understanding the nature of the event and the environments in which they occur.

The other statements reflect accepted knowledge about gamma ray bursts. They are known for their extreme energy outputs and variability in duration, which can indeed span from milliseconds to several minutes. They are recognized as some of the most energetic phenomena in the universe, associated with catastrophic cosmic events like supernovae, and sometimes related to the collapse of massive stars leading to the formation of neutron stars or black holes.