ICY SCIENCE: SCIENCE SPACE ASTRONOMY Spring 2014 | Page 78

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The Importance of Gravitational Waves and the Formation of the
Cosmic Microwave Background

In March 2014 one of the most ground breaking discoveries in modern Astrophysics was made. That was
the discovery of gravitational waves within the Cosmic Microwave Background (CMB). Confirmation of this
discovery will all but prove inflation took place in the wake of the Big Bang, creating the Universe as we
know it. But in order to understand gravitational waves, first we must look at the CMB and how this relates
to inflation.
The CMB is often described as the ‘echo’ of the Big Bang. A form of electromagnetic radiation, it fills the
entire Universe with equal intensity in all directions. This phenomenon was discovered in 1968 completely
by accident by two Scientists – Arno Penzias and Robert Wilson – whilst studying the intensity of radio
waves emitted from our galaxy. In order to show that the radiation they were detecting was being emitted
by the Milky Way, they first had to test for background radiation which they believed would be negligible.
Unfortunately for them, this wasn’t the case. No matter where they pointed their antenna, they found a
faint background noise outside our galaxy. After looking at some calculations and talking with colleagues
they realised they had discovered a blackbody spectrum of around 3.5K being emitted in all directions in the
Universe. They had discovered the CMB.
So we know a little about the when, the where, and the who with regard to the CMB – but what actually is
it? How was it formed, and what does it have to do with gravitational waves and our early Universe?

ICY SCIENCE | QTR 2 SPRING 2014