By - Chanuda Edirisinghe
The Earth, the moon, solar system, the entire Milky Way and the thousands of galaxies closest to us spread apart each second. The cosmic space currently has a diameter of 250 million light-years. This value exponentially increases over time. The universe has been expanding since the Big Bang which occurred 13.8 billion years ago - the theory suggested by Belgian Canon and physicist Georges Lemaître demonstrated by Edwin Hubble has helped many astronomers and astronomy enthusiasts to support their theories and bring out a greater knowledge on what’s in the outer space.
Hubble's Law
In 1929 Edwin Hubble first confirmed that our universe is expanding at an increasing rate. He was able to prove this by being able to conclude: That nearly all deep spaced objects are moving away from the earth.
The further away an object was from the earth the faster away the object was moving from the earth.
His theory on Doppler effect was able to prove this, “the apparent change in the frequency of a wave that is caused by the apparent motion between the observer and the source of the wave.”
This suggests that a source’s direction of the motion can be detected by the frequency emitted by the source. We use a spectrum of light from a star or other object to tell if it’s moving towards us or moving away from us. Stars emit light that gives out specific spectral lines, these spectral lines help Astronomers identify the elements inside stars and galaxies but they can also be used to that the object is moving away or moving towards the observer based on the movement of those spectral lines.
The apparent frequency of the light coming from a star shifts. The light of a star will either shift to the blue side of the spectrum if it’s moving towards the observer or to the red side of the spectrum if it’s moving away from the observer. Hence the term redshift. Light from a star or an object that’s moving away from the earth is termed the redshift, meaning the light from that object is shifted to the red side of the spectrum. Based on how much it shifts we can determine how fast the object is moving towards or away from the Earth.
‘Hubble’s data proving the increase in reaction velocity as further stars are away’
'Hubble's data proving the increase in reaction velocity as further stars are away'.
Edwin Hubble’s conclusion became well-known amongst astronomers and physicists, as his conclusions became key evidence of the Big bang theory. The Big Bang theory suggests that the universe should be expanding, and all things came from one central point. In fact, his findings were able to prove that if we took that universe where everything is moving away and at an increasing rate, we can run all of it in reverse leading all of those things to one central point. This demonstrates a clear understanding of the origin of the universe.
The Theory of the 'The Big Crunch'.
One possibility for the future of the universe is the Big Crunch Theory. As you know the Big Bang theory states that the universe was once a tiny dot of matter. Then, it grew quickly and it became everything that exists today and as discussed earlier the universe is still expanding, carrying galaxies farther and farther away from each other.
The Big Crunch Theory says that one day, the universe will stop growing, caused by a new big bang causing the first big bangs remains to shrink. Creating new Cosmic wave backgrounds removing all that is left from the first Cosmic Waves. This results in the universe growing smaller and give rise to high temperatures. One way to think of this is as ‘the opposite of the Big Bang’. Instead of expanding and cooling, the universe will shrink and heat up. Finally, everything that exists in the universe will collapse into a tiny point, right where it began.
This is something which we all hardly try to believe, this being an unproven theory keeps the presence of life in Earth safe. But what if another Big Bang takes place?
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