The Universe Taking a Selfie For Posterity
Behold the Cosmic Microwave Background Radiation! The most beautiful expression of modern physics, in my view, to this date. The beauty of the Cosmic Microwave Background (or CMB for short) lies within its stunning visual simplicity and the story it tells is the story of the beginning of everything.
In the early stages of the universe, right after the big bang, all matter was condensed in a hot soup of particles. But as the universe expanded, it cooled and slowed down, allowing for more complex structures to form and thus emerged the foundations of all planets, stars and living forms.
Approximately 380,000 years after the big bang (a blink of an eye in cosmic terms), the cooling caused by the universe’s expansion allowed ionized gas to recombine into neutral hydrogen and helium, which is transparent to visible light. Or in simpler terms — if you look up at the night’s sky you might get the impression that between the stars there is only dark vacuum, but that is only because our eyes are adapted to detect merely a sliver of the electromagnetic spectrum, while leaving us oblivious to all other frequencies of radiation, like radio or UV light. However, up until the universe’s 380 thousandth birthday, you could’ve, in theory, witnessed the space glowing brightly in every direction with the full glory of the visible light spectrum.
If only you could witness the universe in its infancy, just before it matured into the transparent and mystifying space we know today…WAIT A MINUTE! you can actually peer into the distant past and see a sort of graduation photo of all the particles in the universe before they spread across billions of light years, and creating literally everything, including us. When I look at my high-school graduation photo (class of 2008), I can’t see anyone who has done as well as the big bang graduates.
That photo is called the Cosmic Microwave Background Radiation. The last eons of the boiling soup phase of the universe branded the sky with an accurate imprint of the radiation emitted in space billions of years ago. That’s why I love it so much! It’s as if the universe took a selfie for posterity. The CMB won’t last forever and will eventually vaporize millions of years from now, but we are lucky enough to live in its warm embrace.
What makes this story even sweeter, is the fact that the CMB was discovered completely by accident, in 1965, by Arno Penzias and Robert Wilson (both shared the Nobel prize in physics a decade later), while they were working on a new radio receiver. To their dismay they kept picking up a noisy interference, that was detrimental to the original purpose of the receiver. Their frustration grew until they realized that the noise was coming uniformly from every direction in the sky, and it dawned upon them that they may have stumbled upon something monumental.
When you’re feeling anxious and overwhelmed, just take a peak at a time when everything was literally so much simpler and so much closer. Just think about the scope of the universe both in terms of time and space, and notice how your day to day adversities seem petty and insignificant in the grand scheme of things.