How did our seemingly infinite Universe come about? This is a question that has been prevalent among philosophers and scholar since the beginning of time. Today, the most widely accepted model that answers this question states that the universe came into existence from one single extremely hot and dense point, and something triggered the explosion of this point that brought about the beginning of the universe about 13.8 billion years ago. As time passed, the Universe expanded, cooled, and became less dense. This is known as the Big Bang Theory.
In short, the Big Bang theory states that all of the current and past matter in the Universe came into existence at the same time 13.8 billion years ago. At this time, the matter all compacted into a “ball” with infinite density and intense heat called a Singularity. This Singularity expanded as the Universe as we know it started to form.
From the beginning:
Scientists have theorized that the universe must have originated at a single point of infinite density and finite time that slowly began to expand. Subsequently, the Universe cooled enough to allow the formation of subatomic particles (neutron, proton, and electron) and eventually the atom. Large cloud clusters of these antediluvian elements consolidated through gravity to form stars and galaxies. This part is pretty much agreed upon by all scientists. However, the earliest times of the universe after the Big Bang is still under speculation. Given that the laws of physics as we know them could not have existed at this time, it is difficult to fathom how the Universe could have been governed. However, there are many theories that have been proposed on what took place in this initial span of time.
Evidence of the Big Bang
To call the Big Bang merely a theory is to misjudge the overwhelming amount of evidence. There are independent pieces of evidence that all point to the Big Bang as the most plausible answer to the Origin of the Universe.
1. The Amazing Discovery that All Galaxies are Moving Away from Us
In 1912, Vesto Slipher calculated the speed and direction of spiral nebulae by measuring the change in the wavelengths of light coming from it. He noticed most of them are moving away. These objects were found as galaxies outside of the Milky Way by Edwin Hubble. He observed a special type of variable star that has a direct relationship between the energy output and the time it takes to the pulse in brightness. By finding these variable stars in other galaxies, he was able to calculate how far away they were. Hubble discovered that these galaxies millions of light years away. This suggests that the entire Universe must have been located at a single point billions of year ago.
2. An Abundance of Elements We See Around Us
In the earliest moments after the Big Bang, there was nothing more than hydrogen compressed in a tiny volume with crazy heat and pressure. The entire universe was acting as the core of a star fusing hydrogen to helium and other elements. This is known as Big Bang Nucleosynthesis. As astronomers look out in the universe and measure the ratios of hydrogen, helium, and other trace elements, they exactly match what you expect to find that the Universe was once a really big star.
3. Cosmic Microwave Background Radiation
In the 1960s, Arno Penzias and Robert Wilson were experimenting with a six-meter radio telescope and discovered a background radio emission that was coming from every direction in the sky. From what they could tell, the entire sky measured a few degrees above absolute zero. Theories predicted that after the Big Bang, there would have been a tremendous release of radiation. And now billions of years later, this radiation would be moving away so fast from us that the wavelength of the radiation would have been shifted.
4. Formation of galaxies and large scale structure of cosmos
About 10,000 years later after Big Bang, the universe cooled to the point that Gravitation attraction of matter was the dominant form of energy density in the universe. This mass was able to collect together into the first stars, galaxies, and eventually the large scale structures we see across the universe today.
There are even more lines of evidence. There are fluctuations in the cosmic background radiation. We don’t see any stars older than 13.8 billion years ago. The discoveries of dark matter and dark energy along with the light curves from distant supernovae.
How do you feel about the Big Bang? Feel free to leave a comment below!
Co-Founder and Editor of StemTalksNC