The discovery of red shift and other forms of proof were still not enough for cosmologists to accept the Big Bang theory. They claimed that if the Big Bang occurred, the universe must have been very hot at some point long ago, and thus it must have a temperature today. Many were perplexed, but hypothesized the temperature to be somewhere near 5 degrees K. One could not just go into the cosmos with a thermometer and measure the temperature; there would be too many variables to take into account, making the prediction extremely inaccurate.
Yet, something unexpected occurred. A group of scientist were trying to use their radio telescope to conduct an experiment. There was a slight interference from all directions however. The telescope was cleaned, checked and re-checked. Yet, it still picked up a slight “hiss” from all corners of the sky. No one at the time realized what a monumental discovery this was.
The frequency of this radio signal from the cosmos was measured and recorded. It remained fairly stable through an extended period of time. Through a series of calculations it was discovered that this radio signal described the temperature of the universe, which is about 3 degrees Kelvin. This observation is remarkably close to the hypothesized temperature and once again provided another clue to the mysterious puzzle of the universe origins and the Big Bang.