Most scientists accept that the universe started with the Big Bang. The theory states that around 13.7 billion years ago, all matter in the universe was concentrated into a single, infinitesimally tiny point. It goes something like this: the universe began to expand rapidly through a hot and huge explosion, and is still expanding today.
The Big Bang was also believed as the reason why space and time were created.
Space, time, and all matter originated from a singular point, which then expanded incredibly quickly to form the quark-gluon soup. It kept expanding and cooling down which eventually led to the formation of billions and billions of stars, planets, galaxies, and clusters of galaxies, spanning billions of lightyears in width.
The theory presents a neat account of how everything came into being while explaining many puzzling existent phenomena. Since the early twentieth century, we have observed that far away galaxies are actually moving away from each other. And as they get farther away from us, they move faster too. To help you visualize this expansion, here is an analogy. Say you have a balloon with a bunch of dots on it. You fill the balloon and as the balloon expands, the dots move farther apart.
The only explanation for this apparent expansion is that as we move towards the past, things were closer together than they are now. If you extrapolate this thinking, all matter was once so close together it formed what scientists call, the singularity. Using the data from expansion, they have estimated that this singularity existed almost 13.8 billion years ago.
This prediction is in line with Einstein’s theory of relativity which proves that our universe cannot be static – everything is either moving away or towards one another.
As the most probable scientific theory of the origin of the universe, the Big Bang theory is supported by ample evidence. Check out other interesting facts about the Big Bang theory.
One of the first scientists who formulated the theory was a Catholic priest
The “Father of the Big Bang” theory proved that religion and science did not need to be incompatible. In addition to his work as a Belgian Catholic priest, Georges Lemaître was also an astronomer and cosmologist who studied Albert Einstein’s theory of relativity and observed some of the conditions of the early cosmos in the 1920s to 30s. Through that, he theorized that the redshift of galaxies could be caused by the expansion of the universe and that there must have been an initial moment of creation at the beginning. Through decades, it was known as either the “primeval atom” or the “cosmic egg.”
Lemaître’s theory was outright dismissed by Einstein
Although the idea was guided by his theory of relativity, Einstein dismissed Lemaître’s work in 1927. He was impressed with Lemaître’s findings but was not swayed, saying “Vos calculs sont corrects, mais votre physique est abominable,” which in English means, “your calculations are correct, but your physics is abominable!”
What was there before the Big Bang?
A question that still remains unanswered is, what was there before the Big Bang? Technically, time began with the Big Bang, so there is no “before” to begin with. The concept of existence breaks down if there is no time.
However, in the traditional sense of the word, it is speculated that Big Bang might have been a result of the death of an earlier universe.
Scientists have also speculated that our universe might be one of the infinite number universes, each forming from a “bubble”. This hypothesis is called the chaotic inflation theory.
Another idea suggests that our universe might have been ejected from a black hole. This means that black holes give rise to universes and each black hole in our universe might have given birth to another universe
When Edwin Hubble proved that the universe is expanding; the Big Bang was considered as a serious theory
Lemaître’s initial discovery has become what was eventually known as Hubble’s law. Many scientists before Einstein thought that the cosmos was made up entirely of the Milky Way galaxy. But in the 1920s, Edwin Hubble refuted it as he observed nebulae that were too distant to be part of our galaxy, and were in fact, galaxies of their own.
Hubble further proved that other galaxies are moving away from our galaxy at a speed directly proportionate to their distance from us – making the Hubble’s Law. This was consistent with the idea of the Big Bang that if the universe is currently expanding, then it was smaller, denser, and more uniform in the past.
The term “Big Bang” was actually coined by its leading critic and proponent of an alternative theory
Fred Hoyle, a proponent of the Steady-State Theory, was making a different prediction where he believed the universe continues forever without a beginning. His idea was actually the leading theory since the 1940s to the 60s. During a 1949 radio interview with the BBC, Hoyle considered the explosion idea preposterous, saying, “This big bang idea seemed to me to be unsatisfactory even before detailed examination showed that it leads to serious difficulties.” He meant the term to be derisive but it caught on, and now we’re stuck with it.
The theory explains where all hydrogen and helium came from
Basing on the big bang concept for the origin of the universe, Ralph Alpher and George Glamow published a dissertation in the 1940s, which calculated that the early cosmos was hot and dense enough to make all the helium, lithium, and deuterium present in the universe today. Known as the “Big Bang nucleosynthesis theory,” advanced research on it demonstrated where primordial hydrogen came from. Their work provided further evidence and successful predictions that the Big Bang theory might be correct.
Facts which support the Big Bang theory
Another piece of evidence that supports this theory is the existence of cosmic background radiation – the oldest radiation in our universe. The singularity not only contained all matter but also all the energy in the universe. And when the universe expanded, the high energy electromagnetic radiation cooled down and stretched over time. This cosmic background radiation gives us a peek into the early universe when electrons and protons were combining to form hydrogen atoms.
As we explained above, after the universe expanded, things began to cool down. This means that in the distant past they were hotter. Electromagnet radiation should have stretched over time. For this idea to be correct, we should observe low-energy (stretched) radiation all over the universe. And Arno Penzias and Bob Wilson at the famous Bell labs observed exactly that in 1964, confirming the Big bang theory. The detected presence of a cosmic microwave background radiation was essentially the “heat” left from the original explosion.