History of the Universe Part 1: The Big Bang Theory

Nature is an amazing, beautiful thing. Anyone who’s gazed at the stars at night or taken a hike in the mountains has probably wondered at how the beauty and complexity of our world has come to be. This is the first post in a four part series exploring our knowledge of the natural world and how we’re able to explain how we came to be, also known as the modern scientific point of view. This post looks at the origin of the Universe in the Big Bang and what might have happened before it.

Let’s start at the beginning of the universe. The Big Bang theory is currently the “prevailing cosmological model for the universe from the earliest known periods through its subsequent large-scale evolution (Wikipedia).” This theory says that the universe started small and then expanded to its current state, which is still expanding.

The Big Bang theory explains a lot of phenomenon we observe in the universe today. Among those is Microwave Background Radiation, a thermal imprint of the Big Bang that the theory predicted before the MBR was observed (Wall).

The redshift that is observed in all galaxies is another phenomenon that is explained and supports the Big Bang theory. Edwin Hubble discovered the redshift of galaxies and made the connection to an expanding universe (Howell).  The galaxies appear to be shifted towards the red end of the light-spectrum because they are moving away from us (Howell).  As objects move away from us, the wavelength of the light they emit is lengthened, making the objects appear to be “redder” (Wikipedia).

There are numerous other lines of evidence for the Big Bang, including abundance of primordial elements, galactic evolution and distribution, and primordial gas clouds.

But what happened before the Big Bang?

Some physicists say that something—our universe—came from nothing. Stephen Hawking, a theoretical physicist, says that asking what happened before the Big Bang is like asking what’s north of the north pole—the Big Bang is possibly the beginning of time, so asking what happened before time began is a meaningless  question.

But we don’t actually know for sure whether or not our universe came from nothing. Scientists are able to look back a trillionth of a trillionth of a trillionth of a second after the Big Bang…but before that moment when the universe started expanding, the laws of nature break down and we have no predictive power. There are a couple of theories that explain what might have happened.

  • The Singularity Theory

This theory says that all the matter in the universe was once in one point that was infinitely hot and dense, which then started expanding rapidly. Some physicists oppose this idea because it is based off general relativity, and doesn’t consider quantum mechanics (the study of the very small) which is hugely important when things are happening on such a small scale.

 

  • The Cyclic Model/String Theory/Multiverse Theory

The cyclic model states that our universe didn’t start from a single point, but goes through an endless cycle of “Big Bangs” and “Big Crunches (Wall).” In this theory, our universe is actually made up of eleven dimensions, but we only experience four of them. The universe could be spurred to collapse again when the membranes of these dimensions collide.

 

  • Quantum Fluctuations

It is also possible that before the Big Bang, there was just empty space. Our universe could have started as a quantum fluctuation of energy. Quantum fluctuations are a natural phenomenon and have been observed. For example, a matter particle colliding with its antimatter particle and disappearing, then reappearing somewhere else when they separate.

We can’t know what happened before the Big Bang right now because the laws of physics break down at that point, but these theories attempt to explain it.

If you’re interested in looking into the subject more, follow these links:

https://www.khanacademy.org/science/cosmology-and-astronomy/universe-scale-topic/big-bang-expansion-topic

https://www.khanacademy.org/partner-content/big-history-project/big-bang

 The next post will be about the development of the universe and our solar system.

Works Cited

Howell, Elizabeth. “http://www.space.com/25732-redshift-blueshift.html.” 2 5 2014. Space.com.

Wall, Mike. “The Big Bang: What Really Happened at Our Universe’s Birth?” 21 10 2011. Space.com. <http://www.space.com/13347-big-bang-origins-universe-birth.html?li_source=LI&li_medium=more-from-space&li_campaign=related-test>.

Wikipedia. “Big Bang.” n.d. Wikipedia. <https://en.wikipedia.org/wiki/Big_Bang>.

—. “Redshift.” n.d. Wikipedia.

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