Origins of the Universe
The Cosmic Microwave Background and the Search for Quantum Gravity
Nearly 60 years ago, Nobel Prize-winners Arno Penzias and Robert Wilson stumbled across a mysterious hiss of faint radio static that was interfering with their observations. They had found the key to unravelling the story of the Big Bang and the origin of our Universe. That signal was the Cosmic Microwave Background (CMB), the earliest light in the universe, released 379,000 years after the Big Bang. It contains secrets about what happened during the very first tiny increments of time, which had consequences that have rippled throughout cosmic history, leading to the universe of stars and galaxies that we live in today. This is the enthralling story of the quest to understand the CMB radiation and what it can tell us of the origins of time and space, from bubble universes to a cyclical cosmos – and possibly leading to the elusive theory of quantum gravity itself.
The big bang
The astronomer Edwin Hubble discovered that our Universe has been expanding throughout its history. Rewind the clock and we find that 13.8 billion years ago, all the matter and energy in the cosmos was compacted into a dense, hot state, known as the Big Bang, which left behind the relic radiation of the Cosmic Microwave Background.
This popular model posits that at its most fundamental level, matter is made of tiny vibrating strings. It’s the consequences of the model, ranging from a multiverse of 10^500 universes to four-dimensional membranes floating in a higher-dimensional bulk, which stir up the greatest controversy.
the mystery of inflation
In the tiniest fractions of a second after the birth of our Universe, the cosmos underwent a rapid burst of expansion that smoothed out space, but the identity of what caused this intense ‘inflation’ remains one of the greatest puzzles of cosmology, and some models even suggest that in parts of the Universe, inflation never ended.
LOOP QUANTUM GRAVITY
Is space quantised at the smallest of scales? This theory predicts that is indeed the case, and if true it could pave a way towards a theory of quantum gravity. Moreover, if true, then when applied to cosmology, it implies that our Universe may have not been the first, and that other universes may have come before us..