The Theory of Everything

The Expanding Universe

The second lecture in The Theory of Everything is regarding the expansion of the universe. This chapter begins by discussing our galaxy and some galaxies around us. Only in 1924 did American astronomer Edwin Hubble demonstrate that our universe was not the only galaxy. One of the first historic debates the chapter talks about is static vs expanding universe debates. The novel then continues on by discussing two main topics, beginning with the Friedmann Models. It states Friedmann's two assumptions: The universe looks identical in whichever direction we look, this also would be true if we were observing the universe from anywhere. This helped prove that our universe cannot be static. The chapter continues by talking about pieces of evidence which proved Hubble and Friedmann's beliefs and theories, such as Pennzias and Wilson along with Dicke and Peebles' discoveries. After this the book begins to discuss another very key topic, the Big Bang theory.  The book does not define nor explain what the Big Bang theory is, it simply tells us the beliefs before, during and after the implantation of the theory.







To rate the level of difficulty of this lecture, I would give it a 6/10. The vocabulary had been to my grade level, however the content was slightly more advanced than my capability of understanding. Initially the chapter starts by discussing the thoughts on the universe, and I came across some difficulty understanding the difference between static and non static- expanding universe. In order to figure out the differences between the two, I began by defining them. A static universe, also known as  " Einstein's universe"  it is an infinite and stationary universe. It is neither expanding nor contracting. To begin with, I did not understand the difference between an infinite and an expanding universe. In reality, I am still in darkness of what the differences are. Through a Youtube video (below), I began to understand a little. A static universe would mean that all galaxies are not moving, and all stars would be visible to us here on earth, however the galaxies are moving and the farther the galaxy, the faster it is moving.  What I need to yet research is from what central point are galaxies moving faster away from as you go further? Is there a center to the universe?

1.   The universe is expanding so slowly that the gravitational attraction between the different galaxies causes the expansion to slow down and eventually stop. 

• The galaxies then would start to move towards eachother and the universe would contract 
• The distance would begin at 0 reach maximum then go back to zero

• The distance will begin at 0 then reach maximum, then go to a constant speed

• The disrance begins at  0 but will increase forever, the speed will get smaller and smaller but will never touch 0 again. 

Ideas About the Universe



The book The Illustrated Theory of Everything begins by explaining the different theories and ideas that physicists and philosophers have had in the past. The book initially explains the first published and popular theory by Aristotle in 340 B.C. Aristotle had been the first person to publish content on the fact that the earth is not flat, but rather a sphere.  This chapter discusses many other discoveries, however the most significant one discussed had been Newtons in 1687. That year, Newton published the Principia Mathemalica Naturalis Causae. This document is believed to be the single most important documentation of all time. Not only did he put forward theories of how bodies moved in space and time, but also developed mathematics needed to analyze these motions. After discussing all of these theories before the 20th century, Stephen Hawking shifts his attention to post 20th century theories. In this section of the chapter, Hawking discusses how Newton's theory had been modified to state that large bodies repelled at large distances. But we learn that if stars came close, they would attract not repel, and that if stars began to move farther, the repulsive forces would dominate and stars would move farther. In this section we also learn that before the 20th century, they had believed that the universe had existed forever and was not expanding but stationary. However Edin Hubble tells us that the universe is always expanding, the stars are always moving away from us. I discovered in this section that 10-20 million years ago, all stars were together and this had been a result of the Big Bang. The Big Bang had been when the universe was "small" and indefinitely dense. The Big Bang had been the beginning of our time, anything before the Big Bang is not required to be known as it does not effect what has happened, what will happen or what is happening.

As I came from having absolute no background of physics or the universe, all this material had taken me quite a while to grasp.  The initial reading had led no absolute no intake of any of the theories and information provided, however after the second and third read of this chapter I began to understand what Hawking was attempting to put forward. The fact that I borrowed the Illustrated version of Stephen Hawking's book greatly assisted me. The text of this novel is identical, however it is the footnotes, the images and the attractiveness of the book which assisted me in keeping my interest and helping a "rookie" physicist in learning about the origin and fate of the universe. In order to learn the information provided, I had to do a lot of outside of text research which included discussing my text with peers, using websites and youtube videos.

                                        

My adventure into learning about our universe all began by getting down the basics of what I would need to know. The first question that rose in my head had been "What is the universe?" , " what does it consist of" ? I goggled this question and found the famous Minute Physics. This video set a great foundation for me. I learned that the universe is everything. There are two definitions and types of the universe; Observable universe and the whole Universe. The observable universe is everything we know and can see. The whole universe is literally everything. It is the past, the present and the future. As far as we know, the universe is approximately 13.8 billion years old, and had a beginning. We do not know much on the universe, we know three things; space time, particles and how space time and particles interact to make everything. The next step for me had been to research some information on the Big Bang theory.  After watching numerous videos, reading numerous webpages, I was able to learn some things however not much had been learned. The level of detail exceeds my understanding. I learned that it all began with electrons. Free electrons would cause photons light to scatter. Overtime, the electrons met a nuclei and created neutral atoms which after 380 000 years turned into light. One thing which blew my ming had been that the Big Bang theory was not an explosion but just an expansion.