Big Bang Event

Big Bang Event That Began Our Universe

Ten or twenty billion years ago, something happened – the Big Bang, the event that began our universe. Why it happened is the greatest mystery we know. That it happened is reasonably clear. All the matter and energy now in the universe was concentrated at extremely high density – a kind of cosmic egg, reminiscent of the creation myths of many cultures – perhaps into a mathematical point with no dimension at all. It was not that all the matter and energy were squeezed into a minor corner of the present universe; rather, the entire universe, matter and energy, and the space they fill, occupied a very small volume. There was not much room for events to happen in.

The Big Bang as inception… © Image Megan Jorgensen (Elena)

In that titanic cosmic explosion, the universe began an expansion which has never ceased. It is misleading to describe the expansion of the universe as a sort of distending bubble viewed from the outside. By definition, nothing we can ever know, was outside. It is better to think of it from the inside, perhaps with grid lines – imagine to adhere to the moving fabric of space – expanding uniformly in all directions. As space stretched, the matter and energy in the universe expanded with it and rapidly cooled. The radiation of the cosmic fireball, which, then as now, filled the universe, moved through the spectrum – from gamma rays to X-rays to ultraviolet light; through the rainbow colors of the visible spectrum; into the infrared and radio regions.

The remnants of that fireball, the cosmic background radiation, emanating from all parts of the sky can be detected by radio telescopes today. In the early universe space was brilliantly illuminated. As time passed, the fabric of space continued to expand, the radiation cooled, and, in ordinary visible light, for the first time, space became dark, as it is today.