The astronomer and director of the Hayden Planetarium Neil deGrasse Tyson recently lamented the fact that a Google search of "Big Bang Theory" directs one to the television show first.
This is perhaps not surprising considering the show is amazingly popular and on television two or three times every day of the week (if not more often!)
The television show is also a lot easier to understand than the physics theory. After all, it is a simple premise with two physicists - one theoretical; one experimental - living across the hall from a beautiful aspiring actress/waitress. What could be more commonplace than that?
The big bang theory, on the other hand, posits the beginning of the universe was a singular event in which massive amounts of energy created all of the underlying structure of time and space. That is a little harder to wrap one's head around.
It also says nothing about what came before or why the singularity occurred or how it happened. Just that it did and everything since then has been a probabilistic consequence of that event.
How do we know the big bang occurred?
There is a significant amount of evidence indicating the theory is correct. Perhaps the most compelling is the data collected by NASA's Wilkinson Microwave Anisotropy Probe or WMAP, for short, which was able to map the cosmic microwave background.
We are constantly being bombarded by microwaves left over from the beginning of time. For every particle of matter in the universe, there is something like a million photons and the majority of these photons have stretched to the point of being microwaves.
By understanding what microwave radiation exists in the universe and how it is structured, astrophysicists have been able to wind the clock backwards and show that the universe began 13.798 billion years ago, plus or minus 37 million years.
Of course, as the universe expanded after its initial explosion, the energy content in a given volume decreased. At some point - a couple of minutes or so after the big bang - some of this energy coalesced into particles forming protons, neutrons, and electrons. This transformation is governed by Einstein's equation E = mc^2. If you have enough energy, you can create matter.
At this point, the primordial soup was still too hot to form atoms. It was a plasma of unrelated particles but the constituent particles were present. As the universe kept expanding, as it went through an inflationary period, it cooled off.
This initial cooling period eventually gave rise to hydrogen, deuterium, tritium, helium-3 and helium-4. It might have also generated a little bit of lithium. About 380,000 years after the big bang, the universe had cooled enough - it had expanded enough - to become transparent to radiation.
Light was no longer constrained but could move free of matter. It is this transition we observe when we look at the cosmic microwave background. As the fog cleared, high energy electromagnetic radiation filled the space in the universe.
Over time, the continued expansion and cooling of the universe stretched the wavelength of this background radiation into the microwave region of the electromagnetic spectrum.
We also know from the microwave background that the first stars formed only 200 million years after the big bang. That might seem like a long time but in the cosmic scheme of things it is a relatively short interval.
From other evidence, we know many of the early stars were massive and burned their fuel rapaciously. They collapsed into super novae. In doing so, they generated all of the elements in the periodic table. Hydrogen and helium were forced together to give the nuclei for carbon, oxygen, silicon, and iron.
Over time, these massive stellar manufacturing plants have given rise to all of the elements around us. The world we occupy and the atoms in all living things were formed in the cores of countless stars that have exploded to seed the galaxy. Yes, we are all made of stardust.
There is one anomaly in the periodic table which generated questions for early astrophysicists. Lithium is not anywhere near as abundant as it should be. Neither is beryllium or boron. These are the second, third, and fourth lightest of the elements. Based on building atoms from hydrogen and helium, one might think they would be much more prevalent.
However, further validation of the big bang theory is provided by sub-atomic physics which allows us to understand why. It results from the absence of a stable nucleus with five or eight nucleons. This bottleneck restricts the rate at which stars burn. The bottleneck is also circumvented by the triple collision of helium nuclei in massive stars which gives rise to the stable carbon-12 nucleus.
Yes, the big bang theory explains the origins of the universe and everything in it, including the television show "The Big Bang Theory".
