Scientists in Australia have detected great clouds of hydrogen which have been excited by ultraviolet light into a state where it absorbed radiation at a radio frequency of 1.4 gigahertz. Due to the expansion of the universe the detection of the radio waves were actually discovered at 78 MHz. This happened only(!) 118 million years after the Big Bang which is earlier than the first light could be seen at 560 million years after BB. It is suspected that early hydrogen atoms may have interacted with dark matter which has got scientists more excited than the hydrogen. Signal detected from 'cosmic dawn'