Second, there was a time, within the first few hundred million years after the Big Bang, before the stars and galaxies were formed. Attended by the “cosmic dark period”, this time naturally makes a challenging astronomical target because there were not many bright sources to create Light light for us.
But neutral was hydrogen. Most of the universe is made of hydrogen, making it the most common factor in the universe. Today, almost all of all of it is hydrogen ionized, which is in a very hot plasma state. But before the first stars and galaxies appeared, the cosmic reserves of hydrogen were cool and neutral.
Neutral hydrogen is made of the same proton and the same electron. Each of these particles contains a quantum property known as the spin (like the familiarity of such spin, resembles macroscope property, but it is not the same – though it is a different article). In its lowest energy state, the proton and the electron will be going to rotate in the opposite direction. But sometimes, purely randomly quantum opportunity, the electron turns out. Very soon, hydrogen took notice and transformed the electron from where it was concerned. This process releases a small amount of energy in the form of photon with wavelengths of 21 cm.
This quantum transfer is extremely rare, but with considerable neutral hydrogen, you can make enough signals. In fact, 21 cm of radiation observations are widely used in astronomy, especially to make cold gas reserves maps inside the sky.
Therefore, the dark ages are not completely dark. Those clouds of early neutral hydrogen are eliminating a huge amount of 21 cm of radiation. But this radiation was excluded in the past, which was 13 billion years ago. As he has traveled from the cosmic distance, all these billions of light years in the way of our anxious telescope, he has experienced the effects of the red -color of our spreading universe.