On the 20th of May 1964, Robert Wilson and Arno Penzias were working in their lab, when their antenna picked up a buzzing sound that seemed to come from every direction. What they had accidentally discovered was cosmic microwave background radiation (CMBR) – the noise produced by the big bang. Through the story of Wilson and Penzias we will explore the origins of the universe.
Arno Penzias and Robert Wilson worked in Bell Labs in America in the 1960s. They were experimenting with a 20 ft horn antenna that was built to detect radio waves coming from satellites. To measure these very faint radio waves, they had to remove any interference from their antenna. They removed any signals coming from radio and TV broadcasts. They even used super cold liquid helium to cool their antenna to -269 oC to eliminate heat! After doing this, they still found a low, steady, mysterious noise coming from their antenna. So to explain this, they did what we all would do…. blame the pigeons! There was a family of pigeons living inside their antenna so Penzias and Wilson assumed the noise had something to do with them. After throwing the pigeons out of their new home (and cleaning up the droppings) they found that the hum was still there, coming from all parts of the sky. After consulting with some other scientists, they discovered that the noise matched the predictions of the cosmic microwave background radiation (CMBR), the signature left over from the big bang, the starting point of our universe. When the big bang occurred, a huge amount of energy emerged from an infinitely small point. This energy produced a noise, which is still being sent through the universe as we speak. This is what Wilson and Penzias had discovered, completely by accident. The pair won the Nobel prize in 1978 for their discovery, which helped to support the Big Bang theory.
So how did our universe begin?
Nearly 14 billion years ago, it is speculated that space, time, matter and energy came into existence. This moment is called the Big Bang and is currently the best model that physicists have to describe the origins of the universe.
The Big Bang theory proposes that everything in the Universe came into existence in a single instant from a single hot, condensed point which we call a singularity. This was infinitely small with extreme temperatures of 1000 trillion trillion degrees. There was also one fundamental force which would later split up into the four fundamental forces of our Universe (gravitational, electromagnetic, strong nuclear and weak nuclear). A split second after the Big Bang, the Universe started expanding, matter was created from the energy of the singularity to form fundamental particles like protons and neutrons. From here, the universe started to expand and the temperature decreased. This all sounds very hard to understand or imagine, which is why the discovery of the cosmic microwave background radiation (CMBR) by Penzias and Wilson was so brilliant. It showed proof of the Big Bang.
Timeline of the Big Bang
The last 13.7 billion years of our Universe can be broken up into eight difference eras. The different eras can be broken down as follows:
- The Planck Era: This is the only part of the model that physicists cannot describe. We have no idea what happened in this era!
- The Grand Unified Theory Era: The single force in the Universe splits up into the four fundamental forces we know today (gravitational, electromagnetic, strong nuclear and weak nuclear)
- The Inflation Era: The Universe begins its expansion. In a very short time, the Universe went from being billions of times smaller than a proton to being about the size of a GAA pitch.
- The Quark Era: Subatomic particles are created (protons, neutrons, electrons)
- The Hadron Era: More protons and neutrons are created when the universe has cooled enough for them to develop.
- The Nucleosynthesis Era: Neutrons begin converting into protons. This means there was much more protons in the Universe. The first Helium nuclei are created. We are just 100 seconds after the Big Bang.
- The Opaque Era: Massive amounts of interaction between electrons, protons, neutrons and helium nuclei. This lasts for 300,000 years! This set the stage for the formation of the first atoms.
- The Matter Era: This is the era we are in at the moment. The first atoms began to form, which created even more elements and as a result, stars and planets begin to form out of space dust.
If the Big Bang is how the Universe began, how will it end?
The two main theories for how the Universe will end are called the Big Crunch and the Big Chill. The Big Crunch would be like a reverse Big Bang, where all the matter in the Universe would spontaneously condense back into a singularity. However, current science says this is not likely to happen. The Big Chill would happen because of the expansion and cooling of our Universe. All matter would be locked in dead stars and planets, causing black holes which could leave nothing but a dark, cold Universe. This is the most likely outcome but, because of the large timescales of these processes, we have nothing to worry about really!