"Given enough time, hydrogen starts to wonder where it came from and where it’s going."
For those of us who don’t believe in Creationism, the dawn of man has always been a mystery, and much more elusive, was the inception of the universe. In the past century alone we have made numerous discoveries that give us some insight on how the universe was born. The Big Bang Theory is the most widely accepted theory that explains the beginning of our universe, and rightfully so. There is an extent of evidence that demonstrates that the Big Bang Theory is at least a reasonable deduction.
According to the Big Bang Theory, our universe began as a singularity, meaning that everything that exists today was once huddled together in the smallest possible unit of space observable; literally the smallest fiber of space-time. The universe was so dense and so bustling with energy and the temperature was so high that the four fundamental forces, electromagnetism, gravitational, and weak and strong nuclear forces, were just one different fundamental force. Then suddenly, when the universe was only 10^-43 seconds old, this force caused the universe to go “bang” and it did it in a big way. But, contrary to popular belief, it didn’t go bang at all. Rather, space and time itself stretched at an inconceivable rate. This process is called “inflation”. A millionth of a second into the birth of our universe, inflation had finally stopped. The universe expanded still, just at a much slower rate. The expansion of the universe made the overall density of the universe drop significantly, as well as the temperature of the universe. This allowed the four forces to separate, and it was after this point that the raw energy of the universe materialized into matter. About a second into the big bang, you have the basics of matter: quarks, protons, neutrons, leptons, and hadrons, however, you also have their antimatter counter parts. Matter and antimatter begin to annihilate one another and ultimately matter prevails. It isn’t until about 3 minutes after that that the protons and neutrons combine to form the first simple atomic nuclei, which include hydrogen, helium, and trace amounts of other elements. Although the universe has expanded to the point where temperatures drop below the amount needed to undergo nuclear fusion, it is still very hot. So hot, that electrons still aren’t able to bond with atomic nuclei for another 377,000 years! For a period of nearly 400,000 years there was a cloud of plasma (unbound electrons) so thick that light could not pass through it. As a result, when we look 13.5 billion years into the past we can’t see anything at all because light energy could not trespass that cloud of plasma. However, recent research conducted at CERN used gravitational waves and their polarization to “map” what the inside of the plasma cloud was like. After some 150 million years, the universe has expanded significantly. Enough for individual clusters of masses to collapse due to mutual gravitational attraction and form the first stars and quasars. These first stars were incredibly massive and they were the ones that used the simple elements created during the big bang to create more complex elements. These enormous stars then went supernova creating even more complex elements during the explosion. These elements were then dispersed throughout the universe to be used again by other stars. A billion years later, galaxies begin to form. Approximately 9 billion years into the formation of our universe, and a lot of star dust recycling, our solar system is born. It was 4.6 billion years ago when massive amounts of dust, gas, and space debris collapsed into itself to form the Sun and the 9 planets and so began a new epoch in the history of the universe… the birth of life.
What’s really impressive about the big bang theory is the amount of evidence it has as opposed to other theories.
One of the biggest pieces of evidence that supports the Big Bang Theory is the presence of Cosmic Background Radiation, or CBR for short. CBR is ubiquitous in the universe; it’s present at all times even though there isn’t an obvious source. It turns out that CBR is residual radiation from the big bang that has traveled across the universe since the dawn of time. This radiation actually gives space a temperature of ~2.7 Kelvin when really empty space should be nearer to absolute zero. What’s even crazier, is that when making calculations, the scientists plugged in the temperature of space along with the wavelength of the CBR and it all checked out fine. The energy present during the beginning of the big bang and the remnant energy coincide with one another.
Another piece of evidence is the noticeable redshift of distant galaxies. Redshift is part of what is known as the “Doppler Effect” (see gif 3). Ever notice how a police car’s siren when moving towards you sounds a little higher pitched than when moving away from you? That’s because a moving object approaches the waves in front of it while it moves away from the waves behind it. In sound waves, this causes a change in frequency, which is pitch. When it comes to light waves, it changes the frequency, but a change in frequency would imply a change in color. So, because of the Doppler Effect, objects moving away from a point of reference will be redshifted because the frequency will be lower and the wavelength will be larger. Objects moving towards a point of reference will blue shifted since it has a higher frequency and a shorter wavelength. Back in the mid 1900’s when Edwin Hubble was studying galaxies, he noticed that their colors were more inclined to the red side of the spectrum meaning that they were generally moving away from a common point.
The strongest evidence yet comes from the people at CERN who were working on a project called BICEP. This project allowed us to peer further back into time than every before. By studying the polarization of gravitational waves found in CBR, scientists were able to deduce that there was indeed a period of rapid expansion in the history of the universe.
The last sample of evidence comes from cold hard math. Using equations and strict calculations, scientists hypothesized the amount of matter that should be in existence today. They gathered these numbers from the hypothesized models of the big bang, and what’s fascinating about it is that the calculations were almost on point. Pretty incredible considering that we can almost prove how the universe was made, simply by using numbers.
Although the Big Bang Theory is the most widely accepted theory, it still isn’t complete. I hope to see the day where we finally solve these mysteries and look at each other like “why did we think of this before!” Let’s look forward to a better tomorrow, one where we can understand the events of yesterday.