Origin of Our Universe – Gravitational Waves and Cosmic Inflation

Background Cosmic Radiation. Image by NASA.

Cosmology is confusing, yet extremely interesting! Before we get deeper, we actually got the picture of our universe 380,000 years after the Big Bang. Wondering where did we get this baby picture of our universe? Let’s talk from the start.

Our universe 380,000 years after the Big Bang was so hot that all the subatomic particles like protons, electrons were in a state of plasma moving randomly, even light passing through, was scattered or absorbed, which means the whole universe was opaque. After 380,000 years when the universe has cooled and expanded, the electrons and protons combined and formed hydrogen atoms. So finally after moving randomly for 380,000 years, the photon started to move in space for 13.8 billion years not hitting anything until they reached our detector. This is how, we got this baby image of our Universe.

These photons which started as blue light or visible radiation ended up as microwaves by the time they reached us. These reached us by accident, the first picture was detected by two scientists working on something else and found these signals by accident, but the thing is the image was extremely symmetric. After some advancements in telescopes we finally got the picture shown above.

But the non uniformity is important, due to which there are more dense and less dense places, the higher dense places pull the matter around them. And the massive structures like galaxies are made of this.

So, how could we explain this uniformity, which we first encountered? Well… Scientists have proposed a theory called inflation which states that right after the Big Bang, all of a sudden the universe expanded rapidly. It was said that the time taken was a trillionth of a trillionth of a trillionth of a second.

So, how could we prove this theory of inflation? After all, we couldn’t detect the light before 380,000 years after the Big Bang… Maybe we couldn’t detect the light but we can detect something else called “gravitational wave”. It is like when we wiggle a charge we get electromagnetic radiation, similarly if we wiggle a mass we get gravitational waves. These gravitational waves are extremely weak, it is tough to detect them. If the inflation really took place and the expansion happened so rapidly, the gravitational waves from that moment would stretch and squeeze all the matter of the early universe.

To do this we need to record the polarization of light on the image we get. That is exactly what the scientists got. This is one of the most precious discoveries in the field of science.

Image courtesy of NASA.