How Newton saw the universe and how we see the universe now (Introduction to Cosmology)

Not like in the ancient era, we all know how big the universe and how small a tiny piece is. But the formation of the universe still a question for all scientists. They are suggesting many thoughts to solve how this happened. In the ancient era, for them, the Earth was controlling the universe but in the modern era that had been changed. We all know there have billions of stars like our sun in our Milky way galaxy. And, we know that there are many galaxies in this universe, and we all are still observing the universe because we have seen only a tiny small piece of the universe yet. In this article, we are going to discuss how Newton’s era saw the universe and how we see it now.

In the Principia Mathematica book, Newton formulated general laws of motion and Universal gravitational law. He explained the motion of planets and comets, projectile trajectories, and the marine tides, among other things with his laws of motion and the law of universal gravitation.

Newtonian cosmology

Once Newton’s friend, Cambridge theologian, Richard Bentley asked him, “How do you apply the Universal gravitational law to the whole universe?”. Newton replied to him with a series of letters to his friend how he had seen the universe. Newton described the universe that is infinite and static: “The fixed stars, being equally spread out in all points of heavens, cancel out their mutual pulls by the opposite attraction.”

After that, Newton has struggled too of his reasoning about the universe. If a region of the universe has a slight excess of matter, then that region will begin to attract more matter from its surroundings. That region will become denser, and then it will attract more and more matter to it. When happening this, the whole universe will be attracted to this region. That brings a huge question to Newton’s mind because according to his universal gravitational theory, cannot be unstable the stars and matters because it is static and infinite. But in this situation, the universe will be collapsed into one single region, which means instability of gravity. But he could not be able to solve this question.

Cosmology today

Today, what you are going to know is a young science, that only about 100 years old because the Newtonian universe existed for 200 years with some doubts but without any solution.

First, Edwin Hubble showed us that the universe is not static, the galaxies are rushing away from us, and the entire universe is expanding at very high speed. If we consider this expansion backward in time, we realize the universe was much denser and hotter. We believe our known universe originated some 14 billion years ago in a great explosion called Big Bang. We think before the big bang there was no time and space existed. Is that unbelievable? Yes, a bit. You will know what is the big bang in future articles. 

That primary universe like expanding fireball a mixture of subatomic particles and radiation. With time, that fireball was getting cold and produced nuclei and atoms and to stars and galaxies also us! In 1965, Arno Penzias and Robert Wilson discovered a faint signal from the edge of the universe, this helped to prove that the big bang theory was true, and they achieved Nobel prize for that. Einstein’s general relativity in 1915 also roots in the Big Bang. 

That is just an introduction to the modern universe. In the next articles, I am going to talk about What is Big Bang theory, how it happened, and general relativity and a lot more interesting articles for you with simple explanations.

Author- Induwara Bandara

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