Figure showing the big bang expansion mapped into light-year distances
2018- This number represents our current Anno Domini, or AD, year in time. This causes hasty and false assumptions to be immediately drawn, that time began two thousand and eighteen years ago. Lest we forget, that the Before Christ period preceded the AD period, and stretches back to the origin and formation of planet Earth. Moreover, traveling further back in the tube of time, to about 13.7 billion years ago, leads us to the beginning of time as we know it; to the explosion that started it all -the Big Bang.
During a fraction of the first second of time, all the existing matter and radiation is believed to have been in a highly compressed, few-millimetres wide ball of infinite density, known as a singularity. The Big Bang, the creational explosion, released all of this matter and energy, and within a trillion-trillionth of a second, the universe exploded from a tiny point into an entity of colossal size. Slowly and steadily, more complex matter was formed, which gave rise to astronomical bodies like stars and galaxies. Since then, the universe is believed to be continuously expanding, but at a much slower rate.
In 1965, two Bell-labs astronomers, Penzias and Wilson, discovered the Cosmic Microwave Background, which is believed to be a reflection of the seeds of our universe- the remnants of the first light ever produced after the Big Bang. The two scientists found a signal of constant intensity on their radio telescopes, which could not be directly associated with any astronomical source, therefore proving its relation to an ancient astronomical event-like the Big Bang. The light termed as Cosmic Microwave Background is believed to be 13 billion years old.
This has allowed NASA to construct a "baby picture" of our universe, by capturing the oldest light and using it to paint a cosmic portrait of the universe at its birth. So, we are quite literally looking into the past, staring at the history and creation of our cosmos.
So, just as we begin to think that we have solved the riddles of the universe, we realize that we have only seen the tip of the iceberg, and that too, merely its reflection from the past
Image captured by NASA of the oldest light in the universe, where red indicates warm spots and blue indicates cool spots.