Unraveling the Mysteries of the Big Bang Theory: From Einstein's Fudge Factor to the Whispers of the Universe's Birth

Hello! Welcome my lovely reader to the knowledge spot again! Today we discuss deeply into the universe theory. Alright, so, this blog post is a bit lengthy but very interesting indeed. Please embrace your patience and keep your focus to the end! Let's go!

Most physicists believe that the universe was born in a big bang 13.8 billion years ago. In it, the energy that creates everything in the universe we see today was squeezed into an unimaginably small space - much smaller than a grain of sand, or even an atom. Then, this unimaginably hot and dense point - for whatever reason - expanded at an incredible speed.

In the very first second of the universe's existence, our understanding of what was happening is surprisingly good. We know that concepts of time, space, and the laws of physics were rapidly reinforced. From there, order began to emerge from chaos. First came subatomic particles like quarks. Then, larger particles like protons and neutrons. About three minutes later, the universe cooled to 1 billion degrees Celsius. This allowed protons and neutrons to combine through fusion reactions and form atomic nuclei, the electrically charged cores of atoms.

But after 20 minutes, the universe was no longer hot enough to fuse. What remained was a hot soup, a fog of electrons and nuclei of hydrogen and helium. This phase lasted about 380,000 years. Eventually, the universe cooled enough for electrons to join nuclei and create the first atoms. Then, it took hundreds of millions of years for the first stars to form and light up the darkness, and even longer for the universe to begin to resemble what we see today.

Einstein's fudge factor

How do we know all of this? General relativity describes how space, time, and gravity operate throughout the universe. Albert Einstein formulated this groundbreaking theory in 1915. But it was another physicist, Alexander Friedmann, who studied the equations and made a remarkable discovery.

Friedmann found that general relativity naturally describes a universe expanding or contracting. One possibility he considered was that everything we observe today expands from a single infinitely dense point. Published in 1922, Friedmann's work largely went unnoticed.

Five years later, history repeated itself. Belgian priest and astronomer Georges Lemaître did the math once again and concluded that our universe sprouted like a mushroom from a 'primeval atom.' Like Friedmann, Lemaître was dismissed.

It took actual measurements rather than theory to finally convince many scientists that we live in an expanding universe. Astronomer Edwin Hubble became world-famous for discovering that our galaxy is not alone. His subsequent observations in 1929 proved that all galaxies are moving away from us and moving faster the farther they are. Space itself is expanding.

This was a shock to Einstein. He later admitted that he knew his equations indicated the universe must be expanding or contracting when he wrote them. But at the time, he didn't believe it could be true. So, he added a term called the cosmological constant to keep the universe fixed in place - a move he later regretted.

The sign from the whispers of the Big Bang

Despite mounting evidence, others clung to a stable, steady-state universe for decades more. That is until the accidental discovery of the cosmic microwave background in 1964, Robert Wilson and Arno Penzias were working at a super-sensitive radio antenna in New Jersey, USA. They were using it to detect a halo of hydrogen around the Milky Way. But researchers found that wherever they pointed the antenna, day or night, there was always a faint, annoying hum.

For over a year, they checked and ruled out many possible sources of noise. And to be sure, they tested electrical systems, rebuilt parts of the equipment, and even shooed away pigeons from the antenna. However, the noisy hum persisted.

Eventually, physicist Robert Dicke discovered the noise and explained it as the whispers of the big bang: the cosmic microwave background. The cosmic microwave background retains energy from the birth of the universe covering the entire universe. A faint light relic from 380,000 years after the big bang, it's the farthest back we can see with light. Using various probes, we've studied this leftover radiation for decades.

Most recently, from 2009–13, the Planck space probe searched for small temperature differences across the entire sky. These temperature fluctuations are traces of the seeds from which stars and galaxies emerged.

The dark side of the universe

The theory of the big bang was conceived nearly 100 years ago. And scientists and the public have accepted it as the origin of the universe for over 50 years. However, it still holds many mysteries. Most of these revolve around the fact that what we see doesn't quite match what theory tells us. If we follow the evidence, ~95% of the universe is invisible. As a result, physicists added two dark components to make the math add up - and they must exist if general relativity is correct.

Dark energy is the more mysterious of the two. It's a phenomenon unknown that's expanding space everywhere and making the universe fly apart faster than ever. Meanwhile, dark matter, the second mystery, acts as a counterweight.

Astronomer Vera Rubin found convincing evidence for dark matter in the 1970s. From observations of spiral galaxies, she calculated that 90% of the mass in galaxies is invisible and unidentified. Subsequent studies discovered that dark matter is an invisible substance forming a cosmic web throughout the universe. This cosmic web is believed to help form galaxies and keep them from flying apart.

The fact that both are invisible explains why the universe seems much lighter than normal. In fact, we now think that about 68% of the universe is dark energy and 27% is dark matter. But understanding what dark energy and dark matter truly are will help us understand much more about what happened in the big bang.

Physicists are even beginning to address major gaps in the theory of the big bang: what happened before the big bang? What triggered it? How will the universe end? And is this the only universe?

To answer these questions, we first need to understand how physics operates in the very early moments of universe's life, when all of space and time were crushed into sizes much smaller than a proton. And this means somehow reconciling general relativity and quantum theory.

If it can be done, we may finally understand the nature of reality.