This week's episode "Ask A Spaceman" examines the radiation echo of the Big Bang that shaped our universe. While we can not see the radiation with our eyes, it surrounds us everywhere, says Paul Sutter, astrophysicist and Space.com columnist.
"We know as well as we can know that 13.8 billion years ago, the entire observable universe was ̵
After the Big Bang, the universe was extremely small, hot and dense, resulting in extreme physics , Atoms – the building blocks of molecules – could not even form. The usual components of an atom, such as protons, neutrons, and electrons, could not accumulate because of high levels of radiation, says Sutter. Instead, the infant's universe contained an overheated gas, the plasma. [The Universe: Big Bang to Now in 10 Easy Steps]
As the universe expanded, Sutter said the plasma was cooled and finally – after 10,000 years, a fraction of the history of our universe – atoms formed of hydrogen and helium. Soon the universe became permeable to light. Nevertheless, the radiation of the formation of the universe was preserved. Even as the universe expanded and developed, this early radiation remained in the background.
Today, this radiation – the cosmic microwave background – is still visible and shines in microwave wavelengths at a temperature slightly above the absolute zero temperature in the universe. The CMB has a temperature of 3 Kelvin (minus 454 degrees Fahrenheit or minus 270 degrees Celsius) and is visible throughout the sky.
"It's the relic radiation, it's the fossil, it's the baby image of our entire universe, and that radiation surrounds us from all sides," says Sutter. He adds that the CMB was discovered by chance and that he will give more details in a future episode.
New episodes of the series are released weekly on Wednesdays at 12 noon. EDT (1600 GMT), so "Like" the Facebook page Ask a Spaceman or check back later to see more. Sutter also responds to reader questions in every episode. Click here to learn more about Pluto, the Big Bang, and other great themes of the universe.
Sutter is a cosmologist at Ohio State University and a senior scientist at the Columbus Ohio Science Center. He has a long-running podcast, also called "Ask A Spaceman". You can catch all past episodes here.
Follow us @ Spacedotcom Facebook and Google+ . Original article on Space.com .