The Big Bang Theory- Part 1

The birth of the universe is estimated to have taken place around 13 billion years ago. If the Earth were a grain of sand, the universe would be about 37.2 million kilometers in diameter, and it continues to expand at this very second, but how did it get so large in the first place? Where did everything come from? Of course, it is difficult, if not impossible, to prove any theory surrounding the birth of the universe, but the most accepted one is the Big Bang Theory. If not in a scientific context, I’m sure most of you may have heard this phrase before from the SitCom show, “The Big Bang Theory”, but let’s look into what the theory actually is. 

According to this theory, the universe began as a singular infinitely dense point. This point is known as the primeval atom. Around 13.7 billion years ago, something- we can only ever imagine what- triggered an explosion, and this infinitely dense point began to rapidly expand in a “Big Bang”, and that’s how the universe came into existence. Seems like a bit of a reach, doesn’t it? How could the universe we know today ever have been packed into one single atom? While it may seem unrealistic, there is reason to believe that this is true.

If you’ve read my other blog posts, you would know that one of the most mesmerizing things about space that I can’t wrap my head around is its expansion, but what evidence do we have regarding this? The evidence is based on the Doppler Effect. This effect is the apparent change in frequency of a wave for an observer who is moving relative to the source. For example, think about a time you were standing on a busy road with cars passing by. When the car gets closer, the pitch of the sound heard seems to increase, and as it gets further away, the pitch seems to decrease. The frequency of the wave does not actually change, but due to the relative motion to the observer, the frequency seems to increase. Frequency increases as the wave source gets closer to the observer and decreases as it gets further away. According to the electromagnetic spectrum, waves with lower frequency shift toward the red side of the spectrum. Therefore, a redshift is observed when a wave source gets further away from the observer. 

 

How is this relevant to the expansion of the universe? When distant galaxies are observed, it has been found that the frequency of light waves reaching us from those galaxies is decreasing. This means that these galaxies are moving further away from us, and this phenomenon is known as the redshift. This is evidence that our universe is currently expanding, which leads us to believe that it began with an explosion and has been expanding ever since. This is the basis for the Big Bang Theory, but how did the initial explosion create life and all the celestial bodies we know today? Stay tuned to explore this in the next blog post!